Non-Newtonian and transient effects on wall shear stress within a stented artery
Juan Mejia,1, 2, * Rosaire Mongrain,1, 2 Richard Leask4 and Olivier F. Bertrand3
1 Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada
2 Montreal Heart Institute, Montreal, Quebec, Canada
3 Quebec Heart Institute, Quebec City, Quebec, Canada
4 Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada
The flow within a stented arterial segment has been studied numerically. The three-dimensional model corresponds to a realistic stent geometry. Four different simulations are presented here for comparison, corresponding to steady versus transient inlet conditions as well as Newtonian versus non-Newtonian flow properties. Results are compared in terms of their wall shear stress distributions. In brief, statistical moments are employed to evaluate the haemodynamic performance associated with each of the four models as compared to physiologically realistic levels of wall shear stress in an unstented healthy artery. It is shown that neglecting the non-Newtonian properties of blood results in an underprediction of wall shear stresses, which are associated with higher risk of restenosis. Furthermore, it has been shown that the pulsatile nature of the flow can also result in inaccurate prediction of haemodynamic performance, and that the overall error magnitude induced by neglecting transient effects can be as significant as those induced by neglecting non-Newtonian effects. The haemodynamic performance predicted with a transient non-Newtonian model is in general significantly better when compared with a steady non-Newtonian model. Therefore, transient and non-Newtonian properties should always be included as they significantly change the magnitude and morphology of the wall shear stress distribution.