S. S. Varghese, S. H. Frankel, P. D. Fischer, "Direct Numerical Simulation of Stenotic Flows. Part 2. Pulsatile Flow," Preprint ANL/MCS-P1310-1105, November 2005. [pdf]
Part 1 of this study dealt with steady flow through both axisymmetric and eccentric stenosis models, with the geometry and flow conditions selected to match the classic stenotic flow experiments of Ahmed and Giddens. For the range of Reynolds numbers considered, the numerical simulations under study inlet conditions predicted laminar flow in the case of the axisymmetric model, with no disturbances whatsoever, downstream of the stenosis throat (center). In contrast, the introduction of a small eccentricity within the stenosis, 5% of the main vessel diameter at the throat, resulted in localized transition to turbulence in the region beyond six vessel diameters downstream of the throat. The structure of turbulence was found to closely resemble localized structures observed during pipe flow transition at similar Reynolds numbers. As a result of turbulent breakdown, large spatial variations of wall shear stress were observed along the post-stenotic walls.