A non-body conformal grid method for simulations of laminar and turbulent flows with a compressible large eddy simulation solver
A non-body conformal grid method for simulation of laminar and turbulent flows within complex geometries is developed and incoporated into a compressible large eddy simulation (LES) solver. The underlying finite volume solver for the filtered compressible Navier-Stokes equations is based on a second-order dual-time step approach with preconditioning for low Mach number flow simulations. The time marching was done with an implicit lower-upper symmetric-Gauss-Seidel (LU-SGS) scheme. The small scale motions were modeled by a dynamic subgrid-scale (SGS) model. The code was developed in a multiblock framework and parallelized using the message passing interface (MPI).
To satisfy the boundary conditions on an arbitrary immersed interface, the velocity field at the grid points near the interface is reconstructed locally without smearing the sharp interface. To treat the moving interface situation, a field extension strategy is used which resolved the velocity and pressure issues when a moving solid grid point becomes a fluid grid point.
A variety of laminar and turbulent flow problems are considered to validate the accuracy and range of applicability of the method. In particular, flow over a circular cylinder with different Reynolds numbers and Mach numbers is simulated and an order of accuracy analysis is conducted. A turbulent pipe flow is also solved with a Cartesian grid and good agreement of the simulation results with experimental results validates the capability of the current solver in turbulent flow simulations. Then a rectangular duct containing a cylindrical rod is studied and the simulation results are compared to those obtained from body-fitted grid methods. Next, turbulent heated flow simulations with a non-body conformal grid method are discussed. Laminar flow over a heated cylinder with different Reynolds numbers and temperature ratios is simulated first. The characteristic flow properties such as drag and lift coefficients, Strouhal number and Nusselt number are compared to experimental results. Then the simulation of heated turbulent pipe flow with an isoflux boundary condition is presented using the non-body conformal grids. To demonstrate the applicability of the non-body conformal grid method in compressible flows, transonic and supersonic flow over a cylinder are simulated and qualitative results are studied. Next flow over an oscillating cylinder is studied to demonstrate the capability in solving flow over moving objects. Finally, as a representative of complex geometry flow, subchannel flow surrounding two cylindrical rods in a rectangular duct is studied and the simulation results are compared to simulation and experimental results by other investigators.