Direct numerical simulations of steady and unsteady stenotic flows

In this paper, the incompressible Navier-Stokes equations are solved to study the effect of axisymmetric stenosis on the laminar-to-turbulent transition process in steady and unsteady stenotic flows. Prior research studies1-7 have demonstrated that a strong relationship exists between sites of disease and hemodynamic parameters such as wall shear stress. Thus, there is great practical value in quantifying blood flow velocity and pressure fields for the diagnosis and treatment of cardiovascular diseases. Our studies demonstrate a strong dependence of the transitional flow through a stenosed artery model on the Reynolds number, the degree of stenosis, the peak velocity to mean velocity ratio, and the non-dimensional frequency parameter. This paper explores the role of each parameters and identifies which of these (flow and geometry specific) parameters are critically important to describe the severity of a stenosis. The underlying physical mechanisms are highly complex involving three-dimensional, pulsatile flows at the onset of turbulence. Linear stability analysis for both steady and unsteady axisymmetric base flows is employed in order to get a better understanding of the physical mechanisms. The stability analysis results can be closely linked to the direct numerical simulation results presented in this paper.