Abstract
Pulsatile flow in a 3D model of arterial double stenoses is investigated using a large eddy simulation (LES) technique. The computational domain that has been chosen is a simple channel with a biological-type stenosis formed eccentrically on the top wall. The pulsation was generated at the inlet using the first four harmonics of the Fourier series of the pressure pulse. The flow Reynolds numbers, which are typically suitable for a large human artery, are chosen in the present work. In LES, a top-hat spatial grid-filter is applied to the Navier–Stokes equations of motion to separate the large-scale flows from the sub-grid scale (SGS). The large-scale flows are then resolved fully while the unresolved SGS motions are modelled using a localized dynamic model. It is found that the narrowing of the channel causes the pulsatile flow to undergo a transition to a turbulent condition in the downstream region; as a consequence, a severe level of turbulent fluctuations is achieved in these zones. Transitions to turbulent of the pulsatile flow in the post stenosis are examined through the various numerical results, such as velocity, streamlines, wall pressure, shear stresses and root mean square turbulent fluctuations.
Highlights
In the presence of stenosis in an artery, the nature of the flow in the downstream region is significantly changed
In the previous studies for the single stenosis, it has been tested that the flow through the channel in the presence of stenosis is not fully turbulent
It reveals that the effect of the sub-grid scale (SGS) model before stenosis is almost zero at the laminar flow region
Summary
In the presence of stenosis in an artery, the nature of the flow in the downstream region is significantly changed. Ku [1] described in his review article that blood flow exhibits non-Newtonian behaviour in small branches and capillaries, where the cells squeeze through, and a cell-free skimming layer reduces the effective viscosity through artery. He added that in most arteries, blood behaves like a Newtonian fluid where the viscosity can be taken as a constant, and the typical Reynolds number for the blood flow usually varies from one (in small arteries) to approximately 4000 (in large arteries); and due to the cyclic nature of the heart pump, the blood flow is always unsteady and very challenging to investigate properly
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