Hi Alessandro, These small oscillations seem like numerical instability. Poor spatial resolution in the boundary layer or too large timestep can both result in this. If you are using an iterative solver for the global linear system and the convergence tolerance is too large, this can also occur. Cheers Ankang ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Alessandro Alberto de Lima <aalima@usp.br> Sent: 25 March 2022 17:49 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Q3D simulations around cylinders This email from aalima@usp.br 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. Hi. How are you? I am running some cases of flow around cylinders and, for the case of Re = 1000, I get curious results. The lift force history showed strange oscillations like presented in the attached images. I am using SVV with 64 Fourier modes in z direction for the simulations and my mesh was developed following the descriptions found in a recent publication involving nektar++ and OpenFOAM. I believe that the mesh is not the problem. There is another option for pressure solution and force calculations? Have you any idea about what I'm doing wrong? Thank you! Alessandro