AN EFFICIENT MULTIGRID APPROACH TO SOLVING HIGHLY RECIRCULATING-FLOWS

A multigrid solution strategy is presented for the efficient and econo mic solution of highly recirculating incompressible laminar flows. Thi s paper emphasizes the importance of using high order discretizations for the governing equations of motion, in particular the inertia terms , and the enhancement of the overall stability and efficiency of the m ethod through the use of defect correction. The latter enables solutio ns to an accuracy equivalent to machine round-off to be found easily w ith solutions to 'engineering accuracy' being obtained very rapidly on extremely fine grids. These ideas are demonstrated for the solution o f two commonly encountered test problems-flow in a lid-driven cavity a nd flow through a suddenly expanding channel. Results show that procee ding in this way leads to a robust methodology for the solution of a w hole class of problems of this type, which is readily extended to thre e dimensions.