Hi Hongtao, I don't know the reason for large pressure but you can use a localised initial disturbance, for example <FUNCTION NAME="InitialConditions"> <E VAR="u" VALUE="1" /> <E VAR="v" VALUE="0.2 * exp(-x*x-y*y)" /> <E VAR="p" VALUE="0" /> </FUNCTION> You may missing some bracket in your filter, such as <FILTER TYPE="AeroForces"> ... </FILTER> I attached one file I am using for your reference. Best Ankang Gao Research Associate Department of modern mechanics University of Science and Technology of China -----Original Messages----- From:🌸那慢慢🌸 <2644878715@qq.com> Send time:Wednesday, 05/21/2025 23:54:37 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Cylinder-Base terminal error question | This email from 2644878715@qq.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. | Dear nektar++ users and developers, I am using the base in the flow-stability-cylinder for calculations, and I want to accelerate the appearance of vortices by setting the initial conditions to (1, 0.2, 0). However, the pressure error in the final results is very large, and the filter does not output a file. I would like to know why this is happening. XML file attachment. Hongtao