IMPOSITION OF SLIP BOUNDARY-CONDITIONS WITHOUT THE EXPLICIT COMPUTATION OF CONSISTENT NORMALS

Computational fluid dynamics simulations often require the imposition of slip boundary conditions: zero-normal velocity. When the geometry i s complex, the imposition of this type of boundary condition is not tr ivial since the current implementations require the computation of con sistent normals. The slip boundary condition can be viewed as a constr aint to the solution. Hence in the framework of the Lagrange multiplie r approach, we present an accurate general implementation of consisten t normals. With this new approach, these consistent normals are not co mputed explicitly at the expense of adding new unknowns - the Lagrange multipliers of the constraint - which can be interpreted as normal fo rces on the flow. (C) 1997 John Wiley & Sons, Ltd.