******************* 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, When I run a 2.5D simulation with a coordinate transformation and an extra passive scalar transport, I get the following error: CG iterations made = 5001 using tolerance of 1e-09 (error = -nan, rhs_mag = 1) Fatal : Level 0 assertion violation Exceeded maximum number of iterations However, if I repeat the simulation without the passive scalar transport, it proceeds correctly. Has anyone else encountered the same problem? If so, would you be able to assist me in resolving it? Thank you in advance for youe help, Antonio.