A non-parametric discontinuous Galerkin formulation of the integral boundary layer equations with strong viscous-inviscid coupling

Abstract

A non-parametric discontinuous Galerkin (DG) finite-element formulation is developed for the integral boundary layer (IBL) equations with strong viscous-inviscid coupling. This DG formulation eliminates the need of explicit curvilinear coordinates in traditional boundary layer solvers, and thus enables application to complex geometries even involving non-smooth features. The usual curvilinear coordinates are replaced by a local Cartesian basis, which is conveniently constructed in the DG finite-element formulation. This formulation is also applicable to the general convection-source type of partial differential equations defined on curved manifolds. Other benefits of DG methods are maintained, including support for high-order solutions and applicability to general unstructured meshes. For robust solution of the coupled IBL equations, a strong viscous-inviscid coupling scheme is also proposed, utilizing a global Newton method. This method provides for flexible and convenient coupling of viscous and inviscid solutions, and is readily extensible to coupling with more disciplines, such as structural analysis. As a precursor to the three-dimensional strongly-coupled IBL method, a two-dimensional IBL solver coupled with a panel method is implemented. Numerical examples are presented to demonstrate the viability and utility of the proposed methodology.