CFD Challenge: Solutions Using the Spectral Element Solver NEKTAR

Flow problems in cardiovascular mechanics involve complex geometries and pulsatile flow that may give rise to instabilities, especially in pathological cases. High-order methods are particularly suitable for resolving such unsteady phenomena whereas low-order methods may exhibit excessive dissipation and hence suppress any such physical instabilities. This, for example, is the case for certain type of cerebral aneurysms, see [1], for which we have demonstrated that shear layer instabilities may be triggered even at physiological flow rates, giving rise to audible frequencies in the range of 10Hz to 50 Hz. Similar phenomena may be present in stenotic arteries, where a jet type flow may develop that is also susceptible to temporal instabilities, especially during the decelerating systole.