preferred over another and how the designs could be improved by changing variable limits, constraints, and requirements.

COMPUTER-AIDED ENGINEERING

Aerodynamics / Fluid Dynamics

CFD (computational fluid dynamics) tools are generally used to evaluate the performance of a product in gas or fluid atmospheres (e.g., aircraft wing design). CFD provides an understanding of key fluid dynamic interactions with a three-dimensional description of flow. Various methodologies are available, including partial Navier-Stokes, full Navier-Stokes, and hybrid approaches.

Panel methods solve a linear partial differential equation numerically by approximating the configuration surface by a set of panels. Various methodologies are available to the analyst.

Propulsion

CFD (computational fluid dynamics) tools—see "Aerodynamics / Fluid Dynamics" section.

Thermal Modeling

Aeroheating analysis tools are typically used to define the thermal environments that a product's structure will be exposed to and in which it must perform its function. Various technologies are employed, including finite difference, finite element, and CFD.

EMP (electromagnetic pulse) / lightning strike analysis tools are used to assess the survivability of a product to these phenomena—whether natural or human-induced.

Environmental analysis tools are used to describe the environments to which a product is subjected, including temperature, pressure, humidity, and others.

Reentry analysis tools are used to analyze the aerothermal environments specific to vehicle reentry.

TPS (thermal protection system) analysis tools are used to design and analyze the performance of the systems that are used to protect or insulate a product from the thermal environments to which it is exposed.

Structural Analysis

Ballistics damage tools are used to assess the effect of load path loss on dynamic response and aeroelastic margins. Local damage can be predicted with high-fidelity nonlinear finite element tools. The overall changes to dynamic response and aeroelastic margins are then evaluated relative to their effect on aircraft performance.

Damage tolerance tools are used to predict residual strength in the presence of flaws and the remaining service life given crack growth arising from such flaws. The flaws could be inherent material discontinuities or a result of fatigue, corrosion, or accidental damage. Various methods



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