Further research is required to provide insight into this behavior. This methodology clearly had difficulties with separation and shock phenomena. Research is needed on boundary element methods, which seem to be naturally well suited for the exterior problems of acoustics, parallel computing, modeling techniques for the effects of turbulent boundary layers, and new algorithms for treating resonance and problems with multiple scales.
More detailed comments are given below on specific areas in CFD that require research advances during the next decade. These issues lead to questions regarding the comparison of classical shock fitting and solutions with three-dimensional Riemann solvers.
These conditions range from very low speed incompressible flows where small general aviation aircraft operate to the very high Mach number flight regimes of the National Aerospace Plane NASP machines such as the aero-assisted orbital transfer vehicles AOTV.
A more satisfying approach may be to attempt to model these flows with more general flow theories. Many research areas discussed elsewhere in this report impact on acoustical simulations and must be pursued if there is to be any progress. On the other hand, discrepancy among the results of the viscous flow simulations remains large, and three-dimensional unsteady simulations remain out of reach of contemporary CFD capabilities.
For many years, aircraft-design-oriented CFD was mostly concerned with the solution of potential flow equations by panel methods. In this light it is worthwhile to expend effort in direct attacks on solutions of the Boltzmann equation.
Flows over intakes at high angle of attack separate and cause significant losses in thrust and propulsion system efficiency.
When fluid-structure interactions are considered, such as the interaction of submerged elastic struc- Page Share Cite Suggested Citation:"12 General Computational Fluid Dynamics. Basic considerations attest to the importance of such solvers.