Hi Daniel, Thanks for your email. We fixed one bug in v5.3.0, because the space dimension is not correctly recognized when there are scalar equations. See the following link https://gitlab.nektar.info/nektar/nektar/-/merge_requests/1430 Perhaps you can try a recent version and check if this problem still exists. Best Ankang -- Research Associate Department of modern mechanics University of Science and Technology of China -----Original Messages----- From:"Daniel Garcia" <ribeiro.danielg@gmail.com> Sent Time:2024-01-16 04:25:14 (Tuesday) To: nektar-users@imperial.ac.uk Cc: Subject: [Nektar-users] ReynoldsStresses filter with Scalar Equation | This email from ribeiro.danielg@gmail.com 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 to disable email stamping for this address. | Hello Nektar community, how are you? I'm having some issues with ReynoldsStresses filter when solving inc NS coupled with a scalar equation. In 2D simulation, it runs with the filter, although it outputs RS in the 'z' coordinate (e.g. uw). Also, the average results are somehow different from history points post-processed with the same space sampling and time frequency. As for 3D simulation, the Nektar++ does not run (it crashes) with the error "Level 0 assertion violation. Unsupported dimension". I guess it is confusing the scalar with a spatial dimension. Has anyone already used the RS filter when solving with a scalar equation and know how to workaround this problem? Thank you in advance for your help, Daniel G.