******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Hello everybody, I am currently working on a CG-SVV iLES of a cylinder flow at ReD = 3900 with the IcnNavierStokesSolver and wanted to run some 2D tests first, in order to find an appropriate polynomial order for the wall shear stress to converge in a cheap fassion, as suggested by Guglielmo in another post. I read that for under-resolved simulations it can be beneficial to resort to an equivalent of the Taylor Hood approximation and use a polynomial order for pressure that is reduced by 1 compared to velocity. However, the simulation immediately crashes, if "SPECTRALHPDEALIASING" is activated. If however I define the number of quadrature points manually within the "EXPANSIONS" tag to be at least equal to the amount needed to achieve consistent integration of quadratic nonlinearities or higher, the simulations remain stable. I assume by setting the number of quadrature points like this, global de-aliasing is performed, i.e. all the equation terms are overintegrated, instead of only the convective term being consistently integrated. Whereas by activating "SPECTRALHPDEALIASING" local de-aliasing is performed. Has anybody observed this kind of behavior and has an explanation? The simulation remains stable with "SPECTRALHPDEALIASING" switched on, if I rely on P_pressure = P_velocity for the polynomial order. Thanks and all the best Alex Sicher versendet mit [Proton Mail](https://proton.me/).