Large eddy simulation of stenotic flows: Evaluation of sub-grid scale models and numerical methods

Large eddy simulations (LES) have been performed for 75 % stenosed, eccentric arterial models under steady inlet conditions. A code employing high-order numerical methods for spatial and temporal terms, along with a 2nd order accurate, direct-forcing immersed boundary method for enforcing boundary conditions on curved geometries has been used for simulations. Three sub-grid scale models that have been evaluated are the traditional Smagorinsky model, and recently developed Vreman model and Sigma model. To ascertain the effect of high-order discretization schemes on overall accuracy of the solution, the three sub-grid scale models were also evaluated using OpenFOAM, which is an open-source, finite-volume based solver having a low-order numerical framework. Both mean flow predictions and turbulent statistics in comparison with Direct Numerical Simulation (DNS) data clearly indicate that high-order methods used in conjunction with immersed boundary method can accurately model stenotic flows. Specifically, at Reynolds number of 1000, Vreman and Sigma models predict an early transition to turbulence, in contrast to constant coefficient Smagorinsky Model, which gives the best agreement with DNS data despite having known limitations.