Table 1. Verification and Validation Experiments

Steady

 

  • Flat Plate*

  • Cylinder*

  • Sphere*

  • Prolate Spheroid

  • Wing-Body Junction

  • Inflected Stern

  • Pratt-Whitney Advanced Ducted Propfan (ADP)

  • SUBOFF Configurations

  • Tip Vortex

Unsteady

 

  • Oscillating Flat Plate*

  • Accelerating Cylinder*

  • Vortex Preservation/Convection*

  • Prolate Spheroid

  • Flapping Foil

  • Low Speed Centrifugal Compressor (LSCC)

  • Rotating Propellers

  • Ducted Stage Propulsor (HIREP)

* Includes Verification

4.6 New Computational Tools

Computational design optimization is receiving considerable attention in the aircraft community as a means of aircraft component and full configuration design, and it seems that more attention should be devoted to this topic in the Naval hydrodynamic community. Although computational design, as opposed to to design by analysis, is an area of research that is not routinely used at present, even in the aerospace field, this approach may have tremendous pay-off, and it is believed that this should be an active research area in the ship design community as well.

As computational hardware and software continues to improve, many disciplines (such as hydroacoustics and cavitation) are likely to pursue more direct, physics-based computations of certain phenomenon. For example, in the area of aeroacoustics there is currently a significant research effort devoted to capturing the acoustics directly from the numerical solutions of the Euler equations, rather than using an unsteady surface pressure computation as input to a separate analytical model in order to compute the resulting acoustic signal. It is difficult to do this numerically because the variations in pressure and density that must be resolved are a few orders of magnitude smaller than those that must be resolved to determine aerodynamic coefficients. The equations solved, however, do contain the necessary wave information, if it can be numerically extracted. This numerical acoustics approach does not seem to be receiving the same research attention in the hydroacoustics area, and it is believed that developments in computational technology have matured to the point that this should now be an active area of computational research.

5.0 CONCLUSIONS

An attempt has been made to give a perspective on certain computational Naval hydrodynamic capabilities. This should be considered as the perspective of only one group working in the area, and in view of the particular class of problems with which this group is familiar and has access to, it may not be of general value to the overall Naval hydrodynamic community. A couple of things have, however, surfaced during the preparation of this perspective. Firstly, because these computational problems are extremely difficult and computationally intensive, routine computations will probably not be carried out by many practitioners for the next few years, perhaps 3 to 5 years. Moreover, the field is in a period in which there is an effort to convert research codes to more easily used and supported operational codes. If analogies can be drawn between this discipline and others, this conversion period, unfortunately, may have a rather large time constant. However, this does not mean that large complex practical problems cannot be addressed effectively using present computational hydrodynamic tools, only that software alone is not sufficient to do the the job. Secondly, it seems that the trend will be to incorporate more and more physics into the computational software, as opposed to coupling with separate modeling techniques. This by no means implies that modeling techniques will not continue to be important for years to come. However, it seems that this trend has started and will continue, probably at a faster pace. Finally, much computational hydrodynamics technology has been developed, and more will come in the near future. Equipped with this technology, it seems that expansions to other areas (including multi-disciplinary areas) not presently being addressed will have a high pay-off in the near future, and perhaps should be the dominate research and development areas. Although research and development along the hierarchy of equations should also be pursued, it is believed that the full benefit of unsteady Reynolds averaged Navier-Stokes equations (UnRANS), currently receiving the most attention, has yet to be explored.



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