CFD Challenges in the Aerospace Field
Advances in commercial and military aerospace technology and know-how are continually accelerating and Computational Fluid Dynamics (CFD) has been at the forefront of this progression. Expanding accessibility to affordable, high power computing and the advancement of CFD codes have made optimization simulations of cruise, take-off and landing aerodynamics routine. Complex computational investigations span both external configurations--aeroacoustic, thermal and fluid structure interaction predictions, ground vortex phenomena--and internal configurations--radiation and convection to walls, pollutant formation, internal combustion engines.
The dramatic growth of CFD within the aerospace industry has also brought attention to difficulties in modeling complex flow phenomena and the compromises that remain between physical accuracy and numerical limitations. Trusted, accurate drag predictions in varying flow conditions and geometry configurations, e.g. wing to body fairing, and for different materials, e.g. advanced composites, are a necessity for any aerodynamic design optimization. Solvers must be fast and robust in all flow regimes spanning from subsonic to hypersonic, must accurately capture shock phenomena, and reliably predict boundary layer behavior, flow separation and wing stall. Development in the area of turbulence modeling should improve prediction of turbulent flow fields with secondary flows and vortex separation. Modeling transient flow fields, e.g. rotating machinery, implies the need for additional computational resources to achieve grid independent results, adding another level of complexity and the need for increasingly efficient codes. Aerodynamic design software should also encompass modeling efforts in noise reduction, primarily related to landing gear and wing flaps; efforts that can conflict with aerodynamic optimization and remain difficult achieve. Interior flow analyses of cabins and passenger comfort, including minimization of airflow pressure drop, temperature mixing, and ventilation, while more straightforward flow problems, are also important CFD topics for the commercial aviation industry. CFD codes targeted for aerospace applications should also address specialized needs such as maneuverability analysis, relevant to military applications.
CFD analysis has proven to be a crucial research, development and design tool in the aerospace industry bringing greater insight into the physics of flow, while reducing costs and turnaround time. Quality CFD results reduce dependence on expensive wind tunnel studies and allow for design optimization early in the design phase of a project. The major challenges of the future will be on producing accurate, reliable and fast solver codes that continue to increase the value of CFD.