Aerodynamic Shape Optimization of a Pipe Using the Adjoint Method

Abstract

Shape optimization of an inlet pipe to an engine re-circulator cooler using the adjoint method is presented. The method uses surface sensitivities calculated from an adjoint flow field implemented in the finite volume CFD solver OpenFOAM® [1]. This method allows for computation of the whole sensitivity field with only two solver calls, a primal and an adjoint solver call. A RANS solver with the standard k-epsilon turbulence model applying standard wall functions was used for the primal flow solver. The adjoint surface sensitivities are calculated from the adjoint and the primal flow fields and give information about how the objective function is affected by normal motion of the surface. The surface sensitivities are coupled to a mesh morphing library in OpenFOAM diffusing the motion of the boundary nodes to the internal cells of the mesh. The resulting geometry gave a 6.5% decrease in the total pressure drop through the pipe.