Analysis of Flow Disturbance in a Stenosed Carotid Artery Bifurcation Using Two-Equation Transitional and Turbulence Models

Abstract

In this study, newly developed two-equation turbulence models and transitional variants are employed for the prediction of blood flow patterns in a diseased carotid artery where the growth, progression, and structure of the plaque at rupture are closely linked to low and oscillating wall shear stresses. Moreover, the laminar-turbulent transition in the poststenotic zone can alter the separation zone length, wall shear stress, and pressure distribution over the plaque, with potential implications for stresses within the plaque. Following the validation with well established experimental measurements and numerical studies, a magnetic-resonance (MR) image-based model of the carotid bifurcation with 70% stenosis was reconstructed and simulated using realistic patient-specific conditions. Laminar flow, a correlation-based transitional version of Menter's hybrid k-epsilon/k-omega shear stress transport (SST) model and its "scale adaptive simulation" (SAS) variant were implemented in pulsatile simulations from which analyses of velocity profiles, wall shear stress, and turbulence intensity were conducted. In general, the transitional version of SST and its SAS variant are shown to give a better overall agreement than their standard counterparts with experimental data for pulsatile flow in an axisymmetric stenosed tube. For the patient-specific case reported, the wall shear stress analysis showed discernable differences between the laminar flow and SST transitional models but virtually no difference between the SST transitional model and its SAS variant.

Numerical analysis of the effect of turbulence transition on the hemodynamic parameters in human coronary arteries

“…Neither laminar flow modeling nor Reynolds Averaged Navier-Stokes (RANS) based turbulence models that are developed for fully turbulent flows are suitable for this kind of flows (36)(37)(38). The turbulence model utilized here is the transitional shear stress transport (SST) k-ω model designed to capture the transition, if any, to turbulent state (19,21,26). The transitional model solves the SST k-ω transport equations with two more equations, viz., Eq.…”

“…The model utilizes empirical correlation based strategy to take in to account the effect of pressure gradient, external turbulence level and transitional length on turbulent transition and local flow parameters. Further details of this model with validation and justification of using this model in physiological flow conditions were reported by (26).…”

“…Transitional shear stress transport (SST) k-ω turbulence model is utilized here to capture the flow transition, if any, to turbulent state. Transitional SST k-ω model has been found to capture turbulence transition and predict WSS better than standard RANS based turbulence models (19,21,26). The onset of turbulent transition during pulsatile flow through coronary arteries is quantitatively analysed by calculating the turbulent kinetic energies at distal locations for varying degree of stenosis.…”

Clinical important hemodynamic characteristics for serial stenosed coronary artery

“…Turbulence can significantly affect the pressure and shear stress downstream of the stenosis [28]. Present simulations carried out over a range of Reynolds numbers (based on the centerline temporally averaged streamwise velocity and the bypass radius) from 250 to 1200.…”

Finite element analysis of a rupture-induced deformation of a carotid atherosclerotic plaque with intraplaque hemorrhage

“…The flow patterns in moderately and severely stenosed carotid arteries have been simulated by transitional turbulence flow models (Tan et al, 2008). In this study, we chose the RNG k-ε turbulence model (Yakhot et al, 1992), a two-equation turbulence model for turbulence kinetic energy k and turbulence energy dissipation rate ε (see Appendix).…”