Adjoint mesh deformation and adjoint-based sensitivities with respect to boundary values

Abstract

This paper presents recent developments related to an adjoint RANS solver, which is part of the TRACE flow solver developed at DLR in particular for applications in turbomachinery. On the one hand, the implementation of an adjoint preprocess is described, which consists of two separate parts. First, the adjoint solution is transformed into a field of sensitivities with respect to grid point coordinates by calculating the derivative of the flow equation residual with respect to these coordinates. Second, an elliptic grid deformation procedure is adjoined in order to translate these sensitivities to surface values. The aim is to reduce the computational cost for sensitivity evaluations in applications with a large number of parameters by avoiding the generation of deformed volume grids. Furthermore, the evaluation of sensitivities with respect to boundary values, i.e. average quantities (for example pressure) which are prescribed at entry and exit surfaces, is discussed.