Extension of a Non-Oscillatory Forward-in-Time Scheme to Detached Eddy Simulation of Stratified Turbulent Flows With Unstructured Meshes

A detached eddy simulation algorithm is developed based on the non-oscillatory forward-in-time (NFT) multidimensional positive definite advection transport algorithm (MPDATA) scheme for stratified turbulent flows with low or moderate Reynolds numbers on unstructured meshes. NFT MPDATA is extended to viscous turbulent flows for the first time. Viscous diffusion terms and an explicit sub-grid-scale model are included. The working viscosity of the modified Spalart-Allmaras one equation model is transported by an algorithm based on the NFT MPDATA template. The scheme is semi-implicit which solves the linear equation system once per time step. The advantage of the scheme is efficiency and second-order accuracy. Furthermore, an edge-based data structure is adopted such that our scheme is suitable for both structured and unstructured meshes. The linear equation system is solved by an efficient algebraic multigrid (AMG) method. The algorithm is validated using test cases with Reynolds numbers 200 and 5000 over a range of Froude numbers. The flow patterns and dynamic drag coefficients are analysed and compared to numerical and experimental data in literature.