| A large eddy simulation (LES) code is developed from an existing incompressible Navier-Stokes solver based on the finite element method. Taylor-Hood, , and Crouzeix-Raviart, , tetrahedral elements are implemented for the spatial discretization. The time discretization uses a second order accurate, semi-implicit, split time advancement scheme. The semi-implicit scheme employs a backward differentiation time integration scheme for the viscous term and the Adams-Bashforth scheme for the convective term. Convergence results in space and time are reported for the variable viscosity Navier-Stokes solver. The Smagorinsky model is implemented for the sub-grid scale approximation. The resulting algebraic system is solved using a matrix-free conjugate gradient iterative method. Results of isotropic decaying turbulence in a triple periodic cube are compared with direct numerical simulation (DNS) and experimental data. Preliminary conclusions regarding the performance of the element-wise divergence-free Crouzeix-Raviart element compared to the Taylor-Hood element which only assures divergence-free in a weak sense (i.e., over the entire domain) are presented. |
