******************* 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, I have solved the flow around a 2D cylinder using the IncNavierStokesSolver. Attached, you will find an image of the flow field (flowfield.png). As you can observe, there is a recirculation bubble on the upper rear of the cylinder, along with a separation point at the lower rear. I am looking to plot the wall shear stress as: sign(wss_x) * wss_mag. I’ve extracted the data using FieldConvert into a .csv file, which is also attached. I have a couple of questions regarding the postprocessing: 1) At the aft (0.5, 0), there’s an abrupt sign change in wss_x, which is not continuous. I believe this is related to how wall normals are defined in Nektar. To correct this, it seems necessary to multiply the wss_x values for the lower surface by -1. I am not sure about the (0.5, 0) itself. Is there a way to account for this sign change during postprocessing in Nektar? Or would it be possible to apply a preprocessing step in Nekmesh? 2) The simulation was performed with NUMMODES="2" and TYPE="MODIFIED." The edges of each element are duplicated in the .csv file, but the values for these duplicated points are noticeably different (e.g., (-0.4998656761, 0.01158903919) – entries 4 and 5). I suspect this is again related to the normal definitions, as the norm_y values differ significantly. Is there a way to smooth this out, perhaps with a pre- or postprocessing technique? Also, please note that the region between x = -4.35778714e-02 and 4.35778714e-02 on the upper and lower surfaces does not correspond to the cylinder, which explains the gap in the .csv file. Thank you in advance for your help. I look forward to your suggestions. Cheers, Guillermo