Coupling a Wall Diffusion Model with an Immersed Boundary Technique

Abstract

Immersed boundary methods showed a good compliance for a wide range of complex inviscid and viscous flows. Moreover, the high-Reynolds-number regime still remains an open issue. The paper describes a wall-layer approach to answer the need of a model that goes beyond the actual capability of classical wall functions. A near-wall region is established that gets information from the outer flowfield and returns back the wall stress. The latter is obtained by integrating simplified thin-boundary-layer equations along a normal to the wall subgrid. In the outer zone, the compressible Reynolds-averaged Navier–Stokes equations are solved by means of a finite volume method on two- or three-dimensional Cartesian meshes. The classic validation test dealing with a high-Reynolds-number flow over a flat plate is carried out. A benchmark two-dimensional complex flow is numerically investigated to assess the performance of the wall model in case of a pressure-induced separation. The results are compared with both experiments and body-conforming numerical solutions.