Complex CFD for Everyday Use—Practical Applications for Vehicle Analysis

Abstract

Complex CFD for everyday analysis encompasses quick, efficient grid generation and robust, accurate flow solution. These two disciplines — while distinct and possessing disparate constraints — contribute to produce a solution that is limited by the proper application of the selected tools. With simple forethought, the best assets of each discipline can be combined to further enhance the impact of the other. The fusion of unstructured grids and Detached-Eddy Simulation (DES) enhances the optimal benefits of each to provide an accurate, efficient, and robust computational model. The ability of unstructured grid technology to model complex geometries quickly and efficiently is further highlighted by the prism boundary layer and nearly isotropic cells that it creates outside the boundary layer. The tightly clustered boundary layer lends itself to traditional RANS techniques while the isotropic cells clustered in regions of separated flow improve and elevate DES to its optimum performance. Grid adaption has shown promise in a similar manner. By reducing the cell count in benign regions and increasing cells in turbulent regions, convergence is accelerated and accuracy is improved. Time-accurate DES flow solutions obtained with Cobalt will be presented and compared with experimental data. Vehicle analyses — both aircraft and automotive — will be examined and compared to traditional numerical methods for turbulence.