Numerical prediction of inner turbulent flow in conical diffuser by using a new five-point scheme and DLR k-ɛ turbulence model

The internal turbulent flow in conical diffuser is a very complicated adverse pressure gradient flow. DLR k-ɛ turbulence model was adopted to study it. The every terms of the Laplace operator in DLR k-ɛ turbulence model and pressure Poisson equation were discretized by upwind difference scheme. A new full implicit difference scheme of 5-point was constructed by using finite volume method and finite difference method. A large sparse matrix with five diagonals was formed and was stored by three arrays of one dimension in a compressed mode. General iterative methods do not work wel1 with large sparse matrix. With algebraic multigrid method(AMG), linear algebraic system of equations was solved and the precision was set at 10−6. The computation results were compared with the experimental results. The results show that the computation results have a good agreement with the experiment data. The precision of computational results and numerical simulation efficiency are greatly improved.