METHOD OF CHARACTERISTICS FOR COMPUTING 3-DIMENSIONAL BOUNDARY-LAYERS

A numerical method is presented for solving the three-dimensional boundary layer equations for bodies of arbitrary shape (3C3D code). In laminar flows, the application domain extends from incompressible to hypersonic flows, with the assumption of chemical equilibrium. For turbulent boundary layers, the application domain is limited by the validity of the mixing length model used. In order to retain the hyperbolic nature of the equations reduced to first order partial derivative terms, the momentum equations are discretized along the local streamlines using the osculator tangent plane at each node of the body-fitted coordinate system. With this original approach, it is possible to avoid the need for generalized coordinates and therefore it is not necessary to introduce further hypotheses concerning the regularity of the mesh in which the boundary conditions are given. This makes it possible to limit and sometimes even avoid altogether having to preprocess the data from an inviscid calculation. Although the proposed scheme is only semi-implicit, the method is still numerically very efficient.