******************* 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. ******************* Dear all, I am trying to simulate a flow induced by a rotating sphere (so I am working with a 3D mesh). I would ramp up the rotation rate from zero to a constant value over a finite time. So, I need to set an angular velocity on the sphere's surface. To do this I would use spherical polar coordinates (r, theta, phi), with corresponding velocity components. Then, I would solve the Navier-Stokes equations subject to my time-dependent boundary conditions. I have seen it is possible to specify time-dependent boundary conditions through the setting USERDEFINEDTYPE="TimeDependent". However, in this case, I also need to change my coordinate system from Cartesian to Spherical. Is this possible? I have seen it is possible to do coordinate transformations by activating the mapping technique so PROPERTY="SolverType" VALUE="VCSMapping". Will this work on a 3D mesh? I have started to write my new coordianates as <FUNCTION NAME="Mapping"> <E VAR="x" VALUE="sqrt(x*x + y*y + z*z)" /> ---> this would be r = radius <E VAR="y" VALUE="atan(sqrt(x*x + y*y) / z )" /> ---> this would be theta = inclination <E VAR="z" VALUE="atan(y / x)" /> ---> this would be phi = azimuth </FUNCTION> using mapping type "General". Now, I am not sure about the MappingVel function (as they will all be 0?) and how this would work in relation to my time-dependent boundary conditions. Could anybody help with this, please? I can also share my code if it can be useful, even though at this stage it is profoundly wrong. Thank you. Kind regards, Silvia