4

Infrastructure

RESEARCHERS AND DEVELOPERS AND THE S&T KNOWLEDGE BASE

Introduction

Naval hydromechanics has its foundations in fluid mechanics, acoustics, applied mathematics, and physics. Students wishing to pursue careers in naval hydromechanics typically earn undergraduate degrees in naval architecture, ocean engineering, mechanical engineering, engineering science, applied mechanics, mathematics, or applied physics before pursuing graduate degrees in the same departments or specialized departments of ocean engineering or naval architecture.

The broader field of naval architecture or ocean engineering, like that of aeronautics, has three major component subfields: fluid mechanics (including propulsion and seakeeping), structures and materials, and stability and control. Students in undergraduate naval architecture programs would usually have a general training in all three subfields before specializing at the graduate level. The skills acquired in other engineering disciplines also find application in naval architecture. Given this broad base from which students may finally pursue careers in naval hydromechanics, it is very difficult to quantify how many students are actually capable of pursuing careers in naval hydromechanics.

It is also difficult to quantify the knowledge base at the other end, the performer base—that is, the number of experienced and accomplished researchers. Specific research problems in naval hydromechanics may attract the attention of researchers from a broad range of specialties in fluid mechanics and related areas. For example, surface ship signatures may depend on the detailed hydromechanics of the breaking bow wave, propeller cavitation, and the bubbly wake, or on other nonlinear problems in free-surface multiphase flows. Free-surface hydromechanics is a research topic of importance not just to naval hydrodynamicists but also to researchers in civil engineering, chemical engineering, physical oceanography, applied mathematics, and numerical analysis.

Fluid dynamics, or hydromechanics, has had a rich tradition of attracting some of the giants of science, mathematics, and engineering: Stokes, Kelvin, Laplace, Rayleigh, von Karman, Prandtl, G.I. Taylor, and Lighthill, to name a few. The applications are important, and the science and mathematics



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An Assessment of Naval Hydromechanics Science and Technology 4 Infrastructure RESEARCHERS AND DEVELOPERS AND THE S&T KNOWLEDGE BASE Introduction Naval hydromechanics has its foundations in fluid mechanics, acoustics, applied mathematics, and physics. Students wishing to pursue careers in naval hydromechanics typically earn undergraduate degrees in naval architecture, ocean engineering, mechanical engineering, engineering science, applied mechanics, mathematics, or applied physics before pursuing graduate degrees in the same departments or specialized departments of ocean engineering or naval architecture. The broader field of naval architecture or ocean engineering, like that of aeronautics, has three major component subfields: fluid mechanics (including propulsion and seakeeping), structures and materials, and stability and control. Students in undergraduate naval architecture programs would usually have a general training in all three subfields before specializing at the graduate level. The skills acquired in other engineering disciplines also find application in naval architecture. Given this broad base from which students may finally pursue careers in naval hydromechanics, it is very difficult to quantify how many students are actually capable of pursuing careers in naval hydromechanics. It is also difficult to quantify the knowledge base at the other end, the performer base—that is, the number of experienced and accomplished researchers. Specific research problems in naval hydromechanics may attract the attention of researchers from a broad range of specialties in fluid mechanics and related areas. For example, surface ship signatures may depend on the detailed hydromechanics of the breaking bow wave, propeller cavitation, and the bubbly wake, or on other nonlinear problems in free-surface multiphase flows. Free-surface hydromechanics is a research topic of importance not just to naval hydrodynamicists but also to researchers in civil engineering, chemical engineering, physical oceanography, applied mathematics, and numerical analysis. Fluid dynamics, or hydromechanics, has had a rich tradition of attracting some of the giants of science, mathematics, and engineering: Stokes, Kelvin, Laplace, Rayleigh, von Karman, Prandtl, G.I. Taylor, and Lighthill, to name a few. The applications are important, and the science and mathematics

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An Assessment of Naval Hydromechanics Science and Technology are interesting and challenging. While specialization within the field has become more common, in the past its leaders distinguished themselves by applying their skills across the entire field. Lighthill, for example, made seminal contributions to aerodynamics, gas dynamics, acoustics, biofluidynamics, and meteorology. The only supporter of hydromechanics research of any import is ONR. However, during the 1990s, ONR, and especially that part of ONR most relevant for naval hydromechanics, became more mission-oriented. That is, it became more concerned with solving specific problems over short time scales than with developing new knowledge that will support naval forces well into the twenty-first century. In view of federal budget constraints, this focus on the short term is understandable, but because of time constraints and limited horizons, short-term, mission-oriented research almost always becomes a synthesis of current knowledge rather than a generator of new knowledge. Individuals attracted to research are more excited by discovery than by synthesis, so the academic pipeline of younger researchers feeding into naval hydromechanics research is directly affected by the relative emphasis that ONR places on fundamentals. In 1956 the Mechanics Division of the ONR used its resources to sponsor the first Symposium on Naval Hydrodynamics. The list of contributors to that first symposium attested to the significance of the field: Milne-Thomson, Lighthill, Stoker, Munk, Longuet-Higgins, Wehausen, Benjamin, Birkhoff, Strasberg, Batchelor, Gilbarg, Plesset, Lin, Klebanoff, and Corrsin. Barely a decade after World War II and well into the Cold War, the need to maintain naval superiority was never far from the minds of those scientists who could contribute to the field. But they were not scientists who made their reputations doing mission-oriented research—they were scientists who attacked problems having broad implications and applications, and they changed their field in the most fundamental ways. Having scientists and engineers of this stature making contributions to the Navy Department's needs in hydromechanics was ONR's goal in the 1950s and should again become its goal today. Over the past 30 years there has been a substantial reduction in the number of programs in naval architecture, but this should not be interpreted as evidence that naval hydromechanics is a fully mature field. For example, although the equations describing hydromechanical flows are well established, they are nonlinear and can be solved analytically only for rather special flows or when linear approximations are adequate. However, important hydromechanics problems can be solved only by numerical methods (see “Computational Simulation of Hydromechanics Phenomena” in Chapter 3). Furthermore, because very different scales can be involved, modeling of the subgrid scale physics is often required, and this presents significant computational challenges. When wave breaking, air entrainment, cavitation, and turbulence are important, as they are in many naval hydromechanics problems, the modeling and computation are more difficult, and current capabilities are not adequate. Thus there are both needs and opportunities for research in naval hydromechanics. But because it is not a field in its infancy, it is more difficult to make rapid advances than it was 30 years ago, so research is even more essential to progress than it was in the past. Distribution of Research Performers Naval hydromechanics research is conducted in three types of institutions: academic, government, and private. The list of FY99 principal investigators in the hydromechanics programs of ONR 333, the Mechanics and Energy Conversion S&T Division, provides insights into the distribution of hydromechanics research across these institutions. Nearly every university department of engineering, physics, or mathematics could be included as a potential performer of hydromechanics research. In the ONR tabulation, 63 of 101 projects were

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An Assessment of Naval Hydromechanics Science and Technology affiliated with academic institutions, but of those, only 8 were in traditional naval architecture departments. Clearly, the bulk of ONR-sponsored hydromechanics research is being conducted at universities, but only a small portion of it is being done in departments of naval architecture. The second category, government laboratories, accounts for 23 research projects in the ONR tabulation. The principal participant is the Naval Surface Warfare Center, Carderock Division with 18 projects. The other participants are the Naval Undersea Warfare Center (2), the Dahlgren Coastal System Station (1), the Naval Postgraduate School (1), and the Naval Sea Systems Command (1). Private corporations and laboratories account for a total of 12 projects. Of these, Science Applications International Corporation, Inc. (SAIC), which has both East Coast (Annapolis, Maryland) and West Coast (La Jolla, California) branches with major hydromechanics capability, has three projects. Other private contractors with one project each include two aerospace companies (Lockheed Martin Astronautics and Lockheed Georgia Co.), one shipbuilder (Bath Iron Works in Maine), and other specialized firms (Dynaflow, Unamachines, Physical Optics, Northwest Research Associates, Pacific Marine & Supply, and Vibtech). Finally, the ONR tabulation lists three projects in three overseas organizations: the Maritime Research Institute of the Netherlands, University College, London, and Ecole Centrale de Nantes, two of which are universities. Another measure of naval hydromechanics research activity can be found in publications in scientific journals. Author location and source of funding were compiled for articles in two of the main U.S. publications devoted to hydromechanics research: the Journal of Ship Research, published by the Society of Naval Architects and Marine Engineers (SNAME), and the Proceedings of the International Workshop on Water Waves and Floating Bodies. Table 4.1 and Table 4.2 list the total number of articles addressing naval hydromechanics issues, the number of articles by authors from U.S. laboratories and institutions, and the number of publications in which the work was sponsored in part or entirely by ONR, as indicated by the authors ' acknowledgments. It is apparent from these two tables that the number of U.S. researchers compared with non-U.S. researchers who had papers published in the two journals has declined dramatically since the 1960s and to a lesser extent within the last 10 years. This drop appears to be consistent with the reduced percentage of ONR acknowledgments, suggesting the importance of ONR funding for U.S. researchers in naval hydromechanics. If the United States is to maintain its naval superiority, it must ensure the vitality of the U.S. research community in naval hydromechanics by providing resources for longer-term fundamental research in the underlying disciplines (e.g. fluid mechanics, acoustics) and for the development of new concepts in naval hydromechanics. Support of longer-term basic research would expand the R&D personnel base by attracting established researchers working directly in naval hydromechanics. Academic Pipeline (Graduate, Postdoctoral, and Career Delineation) The issues that influence student enrollment and career choices are many and complex and certainly beyond the scope of a report such as this. However, some observations can be made that have a bearing on the attractiveness of naval architecture and naval hydromechanics as career choices. Engineering schools are currently dominated by departments of electrical and computer engineering. Undergraduate students are generally concerned with job opportunities and salaries, and those with degrees in these disciplines are in great demand, so naturally great numbers of students are attracted to these fields. Reports of U.S. industry being unable to find enough U.S. citizens to fill positions have made headlines as companies lobby the federal government to liberalize visa quotas for foreign engineers.

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An Assessment of Naval Hydromechanics Science and Technology TABLE 4.1 Hydromechanics Articles Published in the Journal of Ship Research, 1959-1998 Year Totala U.S.b % U.S. ONRc % ONR 1959 15 13 87 4 27 1960 12 11 92 4 33 1961 13 13 100 7 54 1962 14 14 100 8 80 1963 10 10 100 8 80 1964 15 10 67 6 40 1965 22 19 86 10 45 1966 16 13 81 7 44 1967 20 17 85 11 55 1968 18 15 83 10 56 1969 22 20 91 10 45 1989 20 10 50 6 30 1990 18 10 55 7 39 1991 24 12 50 5 21 1992 20 13 65 7 35 1993 20 11 55 8 40 1994 20 8 40 3 15 1995 15 5 33 3 20 1996 20 4 20 3 15 1997 15 7 46 5 33 1998 19 8 42 4 21 aTotal number of articles in year (four issues) on naval hydromechanics subjects. bArticles with lead author from U.S. institution. cONR support acknowledged by authors. TABLE 4.2 Hydromechanics Articles Published in the Proceedings of the International Workshop on Water Waves and Floating Bodies, 1986-1999 Yeara Totalb U.S.c % U.S. ONRd % ONR 1986* 37 17 46 1 30 1987 34 7 21 2 6 1988* 39 17 44 1 2 1989 53 19 36 8 15 1990 49 9 18 2 4 1991* 52 21 40 8 15 1992 54 10 19 1 2 1994 52 8 15 2 4 1995 58 13 22 1 2 1996 48 8 17 1 2 1997 52 8 15 2 4 1998 46 9 42 4 4 1999* 47 10 21 2 4 aAsterisk denotes workshop held in the United States. bTotal number of papers presented at workshop. cPapers whose first author is affiliated with U.S. institution. dNumber of papers acknowledging support from ONR, NRL, or Applied Hydrodynamics Research.

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An Assessment of Naval Hydromechanics Science and Technology TABLE 4.3 Number of Students and Postdoctoral Fellows in Hydromechanics Supported by ONR in FY99 Program Postdoctoral Doctoral Master's Undergraduate Total Submarine hydromechanics 8 22 11 11 52 Surface ship hydromechanics 16 25 12 13 66 Total 24 47 23 24 118 SOURCE: Data provided by Office of Naval Research. At the graduate level, similar concerns affect the student's choice of field, but they are often tempered by personal circumstances (e.g., marriage, family, earnings, and location preference), which may play a larger role in the career decisions of the potential researcher than they did in his undergraduate days. While unique circumstances may lead a student to pursue a research career in naval hydromechanics, the employment choices compared with those for the student of computer engineering are rather limited. While the computer engineering researcher has a vibrant U.S. private industry sector competing for talent, the shipbuilding industry in the United States maintains itself only in niche markets, one of which is shipbuilding for the Navy. The cutting edge of naval architecture in the United States, the place where excitement and innovation are to be found today, is in the design and construction of America's Cup boats, but this is not a large market. Thus, for all intents and purposes, it is only the universities, the government laboratories, and the builders of U.S. naval ships and weapons that can offer stable employment to those graduates who have strong interests in naval hydromechanics. The number of graduate students trained in any field of science and engineering is directly proportional to the level of university research funding in the field. Table 4.3 shows the number of students and postdoctoral fellows engaged in hydromechanics research supported by ONR in FY99. Assuming a residence time of 5 or 6 years in an MS/PhD program and that all holders of master's degrees go on to win PhDs, this support would graduate 12 to 14 PhDs per year. If the MS students were terminal master's students, the number of graduating PhDs would drop to 8 to 10. An average of these estimates would give 10 to 12 PhDs per year, without accounting for attrition, which could reduce these numbers by 25 percent, say, to 8 to 9. Table 4.4 shows the number of academic degrees at the bachelor's, master's, and PhD levels awarded in recent years in naval architecture and related fields. These are not large numbers, especially the number of PhDs. TABLE 4.4 Number of Degrees Awarded in Selected Fields   Bachelor's (1996)a Master's (1996)b PhD (1996)a PhD (1998)b Marine sciences NA NA NA 18 Naval architecture and marine engineering 329 29 7 NA Ocean engineering 167 112 30 29 Oceanography 185 142 105 94 aU.S. Department of Education. 1999. Digest of Education Statistics 1998. bNational Science Foundation. 1999. Survey of Earned Doctorates 1998.

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An Assessment of Naval Hydromechanics Science and Technology In comparing the data of Table 4.3 and Table 4.4 and in drawing conclusions from them, it might be noted that none of the students who were supported by ONR in FY99 were registered in naval architecture departments, so none will get degrees in naval architecture. At the undergraduate level there are substantial degree programs in naval architecture and marine engineering at the University of Michigan at Ann Arbor, the University of New Orleans, and the Webb Institute of Naval Architecture. The ocean engineering BS program at the Massachusetts Institute of Technology serves as a feed for the MS program in naval architecture. Table 4.4 shows that the total number of bachelor's degrees awarded in naval architecture and marine engineering was 329 in 1996. Since the U.S. shipbuilding industry currently hires 250 to 300 naval architects per year, it can be concluded that there is an approximate balance between supply and demand.1 In the past 20 or 30 years, the most significant graduate programs in naval hydromechanics were at the University of California at Berkeley, the University of Michigan at Ann Arbor, and the Massachusetts Institute of Technology. In the past 2 or 3 years, large reductions occurred at two of these programs: the Department of Naval Architecture and Offshore Engineering at the University of California at Berkeley was discontinued and several faculty at the Massachusetts Institute of Technology retired. In-depth expertise in the field of naval hydromechanics in the United States is maintained by an aging cadre of engineers and scientists. At steady state, with professional careers spanning 35 to 40 years, the 7 to 9 PhDs graduating each year in the United States (see Table 4.3 and Table 4.4) would be enough to sustain a population of approximately 250 to 360 professional researchers in naval architecture. The performer base in naval hydromechanics would be even smaller than that were it not for the ability of naval hydromechanics to attract researchers who are trained in broader disciplines. Given the fact that the performer base is biased toward its older members, it is likely that this rate of PhD production will not match the rate of retirements in the short term, leading to a decline in the number of researchers. Universities that have significant programs in hydroacoustics are Boston University and Pennsylvania State University. Universities with faculty members in hydroacoustics-related subjects include Notre Dame, the University of Minnesota, Florida Atlantic University, the University of Maryland, Virginia Polytechnic Institute, and the University of Houston. Some senior researchers at NSWCCD participate in graduate programs by supervising graduate research at Notre Dame and Florida Atlantic University. Most PhD candidates supervised in this way have joined NSWCCD, and they have competence in structural acoustics and hydroacoustics. NSWCCD's Signatures Directorate generally hires mechanical and electrical engineers. In the past, arrangements were made with Catholic University to teach courses in acoustics, signal processing, and fluid mechanics to new engineers. Selected staff members have also been encouraged to pursue graduate degrees during sabbaticals. While there is no large infrastructure in hydroacoustics at U.S. universities, laboratories like NSWCCD still manage to meet their personnel needs by means of the kind described above. Through its enlightened funding of fundamental science and engineering, ONR has built up a loyalty among the principal investigators in academia, and they stand ready and prepared to respond 1   Coincidentally, Japan, formerly the leading shipbuilding country, currently graduates approximately 300 students with bachelor's degrees in naval architecture each year. Anecdotal evidence suggests that not all of them can find jobs in the shipbuilding industry.

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An Assessment of Naval Hydromechanics Science and Technology when ONR or the Department of the Navy needs advice or technical support on more immediate problems. This is an important resource that is difficult to quantify, but it is likely that any further erosion of ONR's tradition of being concerned with fundamental research will lead to a decline in numbers in that community and in their ability to respond. Research Culture in the Department of the Navy Centers The committee has some concern about the research environment at the Department of the Navy centers, which appear to be focused on the performance testing of prototype systems rather than on research that could lead to fundamentally different systems. Testing is important to the Department of the Navy, but so is research, and the strategies for managing testing laboratories and research laboratories are quite different. There may not be enough freedom for Department of the Navy researchers to explore and develop new ideas, and this opportunity needs to be cultivated by the management of these centers. Several researchers in the Department of the Navy centers are highly regarded by their peers in the research community, but their number is relatively small compared with the total number of research staff at these centers, and they are spread across a number of different facilities. Each of the centers is operated independently, and the experts at the various centers do not seem to have much interaction. Most of the centers' work is published in conference proceedings as opposed to refereed journals and thus escapes critical peer review. In contrast, NASA research centers encourage publication in refereed journals. There is a policy to subject all NASA reports to internal peer review before they are submitted. Nothing like this appears to take place in the Department of the Navy centers, even making allowance for the department's work with classified information. If publication was encouraged, perhaps the Navy Department laboratories would attract more of the best and brightest university graduates, and the technical level of their contributions would be higher. RESEARCH FACILITIES FOR NAVAL HYDROMECHANICS TECHNOLOGY The discussion in this part of the report addresses issues related to national asset hydromechanics experimental facilities and active academic test facilities, non-U.S. facilities, and problems associated with the facilities. National Asset Hydromechanics Test Facilities and Active Academic Test Facilities Experiments are now performed at two Department of the Navy centers using the facilities listed in Box 4.1 and at the academic facilities listed in Box 4.2. More details are given in Appendix A. In the United States there is one comprehensive Navy Department laboratory, NSWCCD, with towing tank and water tunnel facilities capable of testing the large-scale models needed in many types of naval studies. Several universities have towing tanks and water tunnels, but except for the tunnels at Pennsylvania State University and the medium-sized towing tank at the University of Michigan, the facilities are small and devoted primarily to teaching and graduate student research. Two large facilities, the Davidson Laboratory and Hydronautics, Inc., have ceased or nearly ceased operation in naval hydromechanics. The latter, based in Fulton, Maryland, was the largest private firm devoted almost solely to naval hydromechanics S&T. Although the company closed a number of years ago, the tank and tunnel facilities still exist, and two small engineering firms continue to use them at a low level of activity, primarily for commercial work. There are two wave tank facilities, one in Texas and one in southern California, focusing primarily on the needs of the offshore oil industry. Not included in Box 4.1 or Box 4.2 but worthy of mention as an important U.S. asset is the Hydronautics Towing Tank and High Speed Channel, the only commercial tank approved by the Maritime Administration for resistance measurements of subsidized ships.

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An Assessment of Naval Hydromechanics Science and Technology BOX 4.1 Department of the Navy Centers and Facilities Naval Surface Warfare Center, Carderock Division Circulating water channel Large cavitation channel Towing basins (shallow water, deep water, and high-speed) Maneuvering and seakeeping basin Rotating arm facility Anechoic flow facility 140 ft basin Research vessel Athena Variable-pressure cavitation tunnels (12, 24, and 36 in.) 8 × 10 ft subsonic wind tunnel Naval Undersea Warfare Center, Newport Acoustic wind tunnel Langley seawater tow tank Research water tunnel Research tow tank Quiet water tunnel Non-U.S. Facilities In Europe, there are a number of large, well-staffed, well-equipped laboratories. Notable installations, comparable in importance and competence to NSWCCD, are the Maritime Research Institute of the Netherlands (MARIN), the Hamburg ship model basin, the Danish Model Basin in Copenhagen, the Swedish Model Basin in Gothenburg (SSPA), and the Norwegian Laboratory (MARINTEK). Most of these laboratories are subsidized by their national governments. All began as ship-testing laboratories devoted principally to the commercial shipbuilding industry, and all have broadened their operations to accommodate the needs of the offshore oil industry. One large European facility, the British National Maritime Institute, at Feltham, was shut down a few years ago, with the relatively new, large-scale model testing tanks being demolished and the land converted to other uses. BOX 4.2 Academic Hydromechanics Research Facilities University of Michigan towing tank University of New Orleans towing tank U.S. Naval Academy towing tank Offshore Technology Research Center at Texas A&M University University of Minnesota water tunnel California Institute of Technology water tunnel Massachusetts Institute of Technology water tunnel University of Iowa towing tank Applied Research Laboratory, Pennsylvania State University

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An Assessment of Naval Hydromechanics Science and Technology In Asia there are a greater number of privately operated facilities as well as some government laboratories. In the latter category are the Ministry of Transportation Laboratory at Mitaka, Japan, and the Korea Research Institute of Ships and Ocean Engineering at Taejon, South Korea. A number of the shipbuilders in Japan, including Mitsubishi Heavy Industries, Ishikawajima-Harima, and Mitsui Zosen Nippon Kokan Kiokai, and in Korea, including the Hyundai Maritime Research Institute in Ulsan and the Daeduk R&D Center operated by Samsung Heavy Industries, operate their own research laboratories, some with towing tanks and tunnels as large as those at NSWCCD. Discussion of Problems Maintainance and Utilization The successful utilization of a facility depends heavily on its quality and condition, which in turn is controlled by the repair and maintenance (R&M) program in place. In the United States, R&M is funded by organizational overhead funds or by a direct surcharge to the project using the facility. In either case, this translates to increased project costs to the sponsor. As a result, significant amounts of hydromechanics testing have gone overseas, particularly to European facilities, which are less expensive to the customer while providing quality data. As foreign facilities continue to attract U.S. businesses, the result is a technology drain to foreign organizations and less use of U.S. facilities, which decreases their efficiency. If the cost of hydromechanics testing in the United States could be reduced, the S&T program would benefit significantly and the use of U.S. facilities would increase. The Department of the Navy has a program called Major Range and Test Facility Base (MRTFB) that funds R&M for test facilities and test ranges. It currently funds mostly aircraft test ranges but is not limited to this use. If these hydromechanics test facilities (see Box 4.1 and Box 4.2) pass the MRTFB composite criteria, they should be funded by this budget item. Instrumentation In general, the instrumentation used in the Department of the Navy centers seems very basic, perhaps because it is used to gather global data (e.g., drag, moments) rather than to address flow physics (e.g., wave breaking, turbulence). At least some of the work at the centers could benefit from more advanced flow measurement techniques, such as particle imaging velocimetry, holography, and other modern, noninvasive optical techniques, and from modern data processing. In addition, new sensors with the MEMS techniques are now available for the measurement and control of fluid flows and are expected to play a role in hydrodynamics. Each of the centers should have an ongoing program of instrumentation modification, but no such programs were mentioned in the presentations to the committee. Flow simulations, adjusted to meet laboratory-scale experiments, are not always accurate when extrapolated to full-scale ships and submarines (see “Scaling to High Reynolds Numbers” in Chapter 3). To improve predictive technology, one needs to better understand the physics, and getting the answer is difficult if one cannot measure relevant physical parameters. There is a need to identify which experi-

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An Assessment of Naval Hydromechanics Science and Technology mental data, taken either in the laboratory or the field, would provide the answers, and then to develop new instrumentation to obtain those data. RESEARCH IN THE COMMERCIAL SHIPBUILDING SECTOR Throughout World War II and the Cold War, the shipbuilding industry was responsible for rapid, high-quality, and high-volume ship production, but it did not participate much in hydromechanics research and development. Industry performed very efficiently during that period in critical design development and ship construction using technology developed earlier by the government. Program- and platform-specific research performed in recent years at U.S. shipyards building warships has increased in both scope and quantity. This is due to mergers, the application of submarine technology, and the Acquisition Reform initiative, which has resulted in funded industry becoming involved in future programs much earlier. This research, however, has been oriented toward platform-specific solutions for a given program, which tend toward nearer-term solutions, not long-term basic and applied research focused on advancing technology. Design authority essentially remained with the Navy until the mid-1990s, when acquisition reform initiatives led to the creation of industry-government teams that competed with one another during the ship design process. Thus there is some research being done in parallel with the design, but it is obviously platform-specific and heavily constrained by the design schedule. Most private shipyards have some hydromechanics research under way in their own independent research and development (IR&D) programs and/or in funded R&D by Navy Department laboratories. Much of this research is focused on hull form development using computational fluid dynamics tools and signature reduction. This research is platform-specific and will not necessarily advance hydrodynamics S&T. If it does not enhance the company's competitive position, no funding will be expended on any research. ONR appears to have recognized this, because its rather substantial effort in CFD appears to be at least partly intended to provide the industry with more advanced design tools. The mergers taking place the past few years have meant that all large U.S. warships are produced by only three corporations (Litton, Newport News, and General Dynamics). The mergers have created a much larger critical mass of engineering talent within these three corporations at a time when a reduction of total ownership costs, best value, innovation, and cost-as-an-independent-variable studies, rather than lowest price, are being used by the government as an important criterion for selecting the winner in competitions. The total number of people in the engineering departments of the General Dynamics shipbuilding “family” (Electric Boat, Bath Iron Works, and National Steel Shipbuilding Company) exceeds 8,000; at Litton it exceeds 2,000; and at Newport News it exceeds 5,000. Of these 15,000 individuals, some 3,000 are degreed engineers, and there is an attrition rate of about 10 percent. This technical talent is partially funded by corporate IR&D budgets, which have become larger in recent years, supplemented by a larger amount of government-funded R&D. This funding is based on past industry activity on government contracts and anticipates the similar involvement of industry in future programs. Increasingly, the three shipyards are contracting with Navy Department laboratories, universities, and private firms to participate in the early stages of shipbuilding programs. Technologies that were once being developed exclusively for future nuclear submarine programs, such as stealth, propulsion, survivability and new materials technologies, are being directly applied to new surface ship programs, such as DD 21, in order to meet specification requirements and respond to the need for increased innovation. This has caused shipbuilders to increase their research in these areas. Research for the commercial sector is usually performed in the same industrial or academic institutions

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An Assessment of Naval Hydromechanics Science and Technology that perform Department of the Navy-supported research. No shipbuilder in the United States has a laboratory and/or testing tank in which any hydromechanics research is performed. Commercial marine hydromechanics research aimed at the commercial shipbuilding and operating market is almost nonexistent in the United States. This has been the case almost continuously for the past 50 years, and certainly since the cessation of commercial shipbuilding subsidies in the mid-1970s. Some funding for research was provided in the past by the U.S. Maritime Administration (MARAD). However, this resource was used essentially for demonstration projects, such as the nuclear merchant ship of 50 years ago, and, later, a commercial hydrofoil passenger ship. More recently, the Maritime Technology Program (Maritech) has received some funding. Maritech, originally managed by DARPA with the support of ONR and MARAD and now managed by the Department of the Navy, is targeted at the application of commercial practices to military shipbuilding. The only substantial hydromechanics project funded by MARAD was the MARAD Systematic Series of Full-Form Ship Models carried out at Hydronautics, Inc., the results of which were published in 1987. This was not fundamental research but, rather, design development intended to produce systematic resistance, propulsion, and maneuvering empirical data for hull forms similar to those of tankers and bulk cargo carriers. Nominal research support is provided by the SNAME hydrodynamics panel, but again, limited funding allows for little more than seed money for approximately five projects per year. Often these small grants enable the principal investigator to develop a new idea in sufficient detail to allow submitting a more comprehensive proposal to other sources for funding. The U.S. ship operating and shipbuilding industry has been noted for its reluctance to support R&D applicable to the commercial industry, primarily because the market is small or nonexistent. The offshore oil industry has seen greater input to R&D projects funded by private sources. Typically, the larger projects are funded jointly by a number of oil and offshore operating companies. While many of these projects involve elements of basic hydromechanics (e.g., the vortex-excited vibration of flexible marine riser pipes), most are development projects centered on large-scale concepts. In recent years, this has resulted in the development of several innovative deep-water oil production platform concepts, including the tension leg platform, the guyed tower, and the spar platform. Owing to the paucity of private research and design expertise in commercial ship hydromechanics, new commercial ships for U.S. owners, whether built in the United States or abroad, almost always have their hull forms and propellers designed abroad, at facilities such as MARIN or SSPA. Examples are the recent container ship designs for Matson and American President Lines. In conclusion, most of the research being performed by the commercial private shipbuilding sector is focused on solving program- or platform-specific, near-term problems for future U.S. Navy shipbuilding programs. INTERNATIONAL RESEARCH IN HYDROMECHANICS Researchers in naval hydromechanics have had frequent and long-standing contact with the international hydromechanics community through semi-open conferences arranged by the American Towing Tank Conference and the International Towing Tank Conference and through open international conferences on cavitation, acoustics, waves, and other phenomena, arranged by various national technical societies. In addition, there are cooperative round-robin tests to evaluate testing facilities, cavitation and propulsion tests, and numerous technical visits. To gain a better perspective on the ONR program in naval hydromechanics and also on the general status of hydromechanics research in the United States in relation to work being done in the rest of the world, the committee sought the advice of two well-respected international experts, Odd M. Faltinsen of

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An Assessment of Naval Hydromechanics Science and Technology the Marine Hydrodynamics Department at the Norwegian University of Science and Technology and Makoto Ohkusu of the Research Institute of Applied Mechanics at Kyushu University in Japan. Certainly, important research is also being undertaken in other countries, but the efforts in Norway and Japan are considered to be quite representative of efforts in other countries, which professors Faltinsen and Ohkusu are well aware of. Research is still far short of being able to predict real flows over ships at sea, with unsteady motion, breaking waves, slamming, water passing over the deck, and other complex effects. An estimate in 1989 suggested that the solution of the Navier-Stokes equations for unsteady water waves would require a teraflops-class computer. Although advances in computer hardware and software have been much more rapid than was then anticipated, computers are still not powerful enough for such simulations. Furthermore, analysis, computational simulation, and experiments need to be interconnected in an effective research program. The Norwegian research is directed toward high-speed surface vehicles, offshore platform technology, and flexible containers. This has led to an emphasis on hydroelastic problems, which require both hydromechanics and structural mechanics. There is also a strong concern with the safety of both surface ships (seakeeping) and offshore platforms. Another area of emphasis is the control of marine systems, which merges the disciplines of hydrodynamics and control theory. Applications include the control of high-speed surface ships, controlled operations of side-by-side ships, and the control of towed objects. Overall, it is fair to say that the Norwegian research program is oriented toward practical applications rather than fundamental phenomena. Likewise, there is a difference in the attitude to research between the United States and the East (Japan, South Korea, and Taiwan). Where the United States emphasizes rational theory and understanding, the East emphasizes short-term results and practical applications. Thus, the West has produced most of the novel ideas and methods in ship hydrodynamics, but the East has been successful in applying them. The direction and emphasis of U.S. and Japanese research in hydromechanics can be compared by surveying the research categories of published papers in the proceedings of the ONR Symposium on Hydrodynamics series and in the Journal of the Japanese Society of Naval Architects of Japan, which can be considered to be representative of the research in the two countries. Box 4.3 lists categories of research and Figure 4.1 shows the relative number of papers published in each journal in the different categories. The two countries have roughly equivalent efforts in most of the first seven categories, which relate to basic ship hydrodynamics, although the U.S. effort on cavitation (category 5) is significantly larger. In categories 8 and 9, experimental techniques and bluff body hydrodynamics, which are more relevant to fundamental hydrodynamics, there is almost no Japanese research. On the other hand, U.S. activity in the more practical applications (categories 10 and up) is very much less than that of the Japanese. The overall conclusion is that U.S. research has a more fundamental orientation while Japanese research is more practical. In computational fluid dynamics, for example, the United States has a greater emphasis on turbulence modeling and validation, while the Japanese have advanced further in the prediction of transverse and maneuvering forces, including the simulation, for example, of the response to rudder motions. In summary, there is a greater emphasis on near-term practical research in other countries. These observations are quite consistent with the different objectives of the shipbuilding industry in the United States and elsewhere. Other countries primarily build surface cargo and passenger ships and offshore platforms, and their research must emphasize issues such as safety, seakeeping, and a reduction of the resistance to motion. The U.S. effort is primarily in support of the needs of the Department of the Navy, so there is more emphasis on submarines and issues related to stealth, such as hydroacoustics, wakes, and cavitation. It appears unrealistic to expect the rest of the world to pursue the kind of fundamental research that is needed to underpin the design of future generations of United States naval platforms.

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An Assessment of Naval Hydromechanics Science and Technology BOX 4.3 Research Categories Computational fluid dynamics (CFD) of ship steady flow (including flow at drift angle) Wave-body interaction Propulsor Resistance (non-CFD) Cavitation Wave hydrodynamics Experimental techniques Bluff body hydrodynamics Turbulence and wake Simulation of ship motion (maneuvering) Fluid mechanics in the ship context Seakeeping Maneuverability Reduction of frictional resistance Special propulsion Environmental and coastal hydrodynamics SOURCE: M. Ohkusu, Research Institute of Applied Mechanics at KyushuUniversity, briefing to the committee October 20, 1999. SCOPE, DEGREE, AND STABILITY OF NON-NAVY ACTIVITIES IN KEY TECHNOLOGIES Historically, fluid mechanics research at ONR has enjoyed a productive partnership with other agencies and military services. The principal members of this partnership with ONR were the NASA Aeronautics Program (and its predecessor, the National Advisory Committee for Aeronautics (NACA)), the Air Force Office of Scientific Research, the National Science Foundation, and, to a lesser degree, the Army Research Office and the Department of Energy research and technology programs. In fact, the core of the early ONR technical experts in fluid dynamics came from the NACA Langley Research Center as well as from the David Taylor Model Basin (now the NSWCCD). This partnership, in collaboration with the academic community and the federal laboratories, produced much of the rapid progress in fundamental fluid mechanics research in the 1950s, 1960s, and 1970s. The Defense Advanced Research Projects Agency has from time to time initiated high-risk and high-payoff advanced submarine technology programs with wide participation of industry. Currently it is supporting advanced sensors and payload development for future submarines. The DARPA programs are of short duration (average of 3 years) and are aimed at demonstrating the feasibility of revolutionary technology concepts. They provide few contributions to long-term research stability or to the fundamental knowledge base.

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An Assessment of Naval Hydromechanics Science and Technology FIGURE 4.1 Relative number of papers published from 1994 to 1998 (see Box 4.3 for definitions of categories 1-16). Light-shaded areas represent the Journal of the Japanese Society of Naval Architects of Japan; dark-shaded areas represent the proceedings of the Symposium on Naval Hydrodynamics series of the United States. SOURCE: M. Ohkusu, Research Institute of Applied Mechanics at KyushuUniversity, briefing to the committee October 20, 1999. As discussed previously, the Department of the Navy transferred more ship design responsibility to the shipbuilding industry as part of Acquisition Reform in the mid-1990s. Industry-government teams were formed to solve short-term design problems, but long-term hydromechanics research is beyond the scope of these teams. Most private shipyards have also begun some hydromechanics research efforts by investing in their IR&D programs. The objectives are to develop their in-house, fast-turnaround CFD design capability and to supplement Department of the Navy R&D so they can improve their competitive positions for new construction contracts. It will take some time before these investments can have an impact on fleet capabilities. It will probably be difficult for the shipbuilding industry to contribute significantly to advancing basic hydromechanics research. Although the Department of the Navy has always had the main need for hydromechanics research and the main responsibility for it, much of the fundamental research and experimentation in turbulence modeling, analysis, and computational techniques was broadly applicable and developed through collaborative or at least leveraged efforts. Time and circumstances have substantially changed this picture. As fluid mechanics research has been applied to more advanced air and water vehicles, the requirements

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An Assessment of Naval Hydromechanics Science and Technology have become more specialized and less broadly applicable. High-speed aircraft, nuclear submarines, and surface ships have diverging technology requirements as both the technology and the vehicles become more sophisticated. In addition, in the past 15 years the total of national resources, in real dollars, devoted to fundamental research in engineering has decreased. As a consequence, federal agencies have focused their resources on their highest priorities and unique needs. Collaboration has been more critically viewed as duplication, and only those activities that would not otherwise be addressed have been encouraged. With everyone doing less and focusing on their own identified unique requirements, the ability of the Department of the Navy to leverage its investments in naval hydromechanics has been reduced and the burden for meeting its own future research and technology requirements has increased. The severe consequences of the current environment are obvious from a macroview of agency resource trends in fluid mechanics research: According to the resources director of NASA's Aeronautics and Space Transportation Technology Enterprise, the NASA aeronautics base R&T budget and investments in numerical aerodynamic simulation have decreased in constant dollars by 17 percent since 1989 and by 28 percent from their peak in 1993.2 Greater emphasis on information science, safety research, and electronic displays and flight controls has reduced aerodynamics investments by a disproportionately large amount. Experimental facilities have been closed and CFD efforts have been reduced. More emphasis is being placed on high-speed and transatmospheric flight, which are less relevant to incompressible phenomena. At the same time, research is focused more in the mid- and near-term, which restricts its applicability. The National Science Foundation (NSF) provides support for fundamental research in fluid mechanics and its application in a broad range of disciplines. Recognizing the key role that fluid science plays in almost every human endeavor, from biomedical engineering to river hydraulics and coastline erosion, research support in the NSF Engineering Directorate focuses on those areas in which research would have the broadest application. Challenges for research cover a very broad range of engineering applications, including materials processing and manufacturing; river and coastal engineering; environmental engineering; essentially all forms of transportation, including advanced automotive technology, quieter aircraft, more efficient ships, and economical means for oil transport; a range of issues in medicine that involve fluid dynamics as it relates to almost every organ in the body; and power generation. The ultimate goal of research in this area is to improve our ability to predict and control the fluid motion in all of these situations. Much of this research is generally relevant to naval hydromechanics, but within the very tight budgetary constraints that exist at NSF, fluid mechanics research in the Engineering Directorate should be viewed as complementary to the Navy's S&T program in hydromechanics. These broad areas in fluid mechanics are supported with an annual budget of approximately $5 million. It is clear that, at these budget levels and with the broad NSF charter, the Navy can rely in only a small way on the NSF to support naval hydromechanics requirements. The Air Force Office of Scientific Research has also been a significant contributor to fundamental research in fluid mechanics. Its scope of responsibilities is more narrowly focused on aerodynamics than the broader Navy scope and its emphasis is more closely aligned with that of NASA. It has also seen a reduction in aerodynamics-related funding of approximately 11 percent in constant dollars since FY92. 3 2   Personal communication on September 9, 1999, between committee member Robert Whitehead and the director of the Resources Management Office, Code R, at NASA headquarters. 3   Data provided by Dr. Joseph Janni and Maj Robert P. Crannage, USAF, of the Air Force Office of Scientific Research, December 6, 1999.

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An Assessment of Naval Hydromechanics Science and Technology The situation with the Army and the Department of Energy is not markedly different from that with the other agencies, but the impact of these two entities has historically been smaller. In summary, the Department of the Navy no longer can depend on complementary and leveraged national efforts to significantly support its unique requirements in naval hydromechanics research and technology. It must develop a strategy and sustainable investment plan to independently ensure its future technology and design capabilities in this area. SCOPE OF NAVY RESPONSIBILITY FOR HYDROMECHANICS RESEARCH There is a growing requirement for greater stealth, speed, and littoral operations capabilities for planned and future naval surface and subsurface vehicles as well as underwater weapons and sensor platforms. The concepts driven by these requirements will place unprecedented demands on Department of the Navy S&T. Concepts such as Sleek Ship are challenges because the required hull/propulsor system is outside the traditional database used by naval architects, and the geometry and fluid dynamics are complex. As ship signature becomes a higher design priority, the traditional database becomes inadequate. A combination of innovative experiments, computational fluid dynamics, and at-sea measurement programs applied by skilled experts will be the most efficient means by which to establish a new, preliminary database. Naval hydromechanics is vital to the body of knowledge required for speed, endurance, stealth, maneuverability, and safety issues, with applications for ships, submarines, exotic vehicles, hydroballistics, detection, platforms, tracking, and harbors. This field of fluid science is characterized by several unique factors that are discussed in detail in earlier sections of this report. In his white paper, Marshall P. Tulin provides an excellent overview of the history of these unique requirements and of ONR's role in naval hydromechanics, along with an expert perspective on both past accomplishments and future prospects.4 He reminds us that many of the theoretical and analytical techniques that proved so valuable in early developments in aeronautics had their foundations in earlier research and discoveries in hydromechanics. The Department of the Navy cannot depend on other agencies or the shipbuilding industry to provide these capabilities. Naval hydromechanics is the special purview of naval research, and it is ONR's responsibility to support fundamental research in this area. To achieve the kinds of successes described in this report (and in the supporting material), the Department of the Navy must renew its reservoir of basic knowledge and expertise in naval hydromechanics, which is vital to its long-term interests. 4   Tulin, Marshall P. 1999. “Naval Hydrodynamics: Perspectives and Prospects.” Santa Barbara, Calif: Ocean Engineering Laboratory, University of California. September 14.