Fast Radial Basis Functions for Engineering Applications by Marco Evangelos Biancolini

Author:Marco Evangelos Biancolini
Language: eng
Format: epub, pdf
Publisher: Springer International Publishing, Cham

Fig. 8.37Back (left) and front (right) underbody shape modifications and their mesh deformation velocities

A 3.8 million cells mesh was employed and CFD calculations are carried out using OpenFOAM coupled with the National Technical University of Athens (NTUA) continuous adjoint solver available through the RBF4AERO platform. The turbulence was modelled using the single equation Spalart-Allmaras model with wall functions. While the flow around the body is not steady, at each optimization cycle the flow and adjoint solutions are computed at steady state proceeding backwards in time. This strategy is applied to avoid the difficulties introduced by the unsteady adjoint solution. As a result, the calculated objective function varies around a mean value during calculation. A deepest descent method with fixed step length is employed for all parameters. After 15 optimization cycles the DrivAer mean drag was reduced by 7% as shown by the plot in Fig. 8.38 reporting the ratio between the drag of the morphed configuration and the drag on the baseline versus the optimisation cycles.

Fig. 8.38DrivAer case: drag reduction with respect to the baseline one for each optimization cycle

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