Numerical simulation of transitional blood flow in large arteries

The flow field downstream of a constriction can be laminar, turbulent, or transitional, depending strongly on the Reynolds number through the stenosis and the geometry of the stenosis. Not only laminar flow modeling but turbulent models such as the k-ε, k-ω, LES or RANS ones are appropriate for this kind of blood flow either. Therefore, in this paper, simulation of the flow field downstream of a constriction with a new approach concentrated upon flow regime has been done. In order to achieve this goal, laminar model was used from inlet up to onset of turbulence. Turbulent model (k-ω SST) since onset of turbulence until relaminarization and finally with starting relaminarzation region, laminar model were applied. Steady axisymmetric flow simulations were accomplished on stenosis with 50 and 75% reductions in cross-sectional area at Reynolds numbers from 500 to 2000 employing a computational fluid dynamics solver, FLUENT (v6.3.17). The results were shown in the terms of axial velocity profiles, disturbance velocity, vortex length, wall shear stress and the results were compared with accepted experimental data and with CFD studies. The axial velocity profiles comparisons show that obtained results are in good agreement with the experimental measurements. Flow simulation results presented that disturbance velocity and wall shear stresses predicted by part by part simulation were moderately close to the experimental data.