******************* 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. ******************* And I use commond FieldConvert -m C0Projection mesh.xml **.fld **-C0Proj.fld. The <EXPANSIONS> in mesh.xml is as same as that in initial-condition.xml. <EXPANSIONS> <E COMPOSITE="C[33]" NUMMODES="4" TYPE="MODIFIED" FIELDS="rho,rhou,rhov,E" /> </EXPANSIONS> Could someone give me some advice? At 2025-02-23 17:10:32, "Gao" <feigao2024@126.com> wrote: Hello, I have much discontinuous (across element interface) distribution of variable in the fluid field. Why this happened? Then I want to use C0Projection module to smooth the fluid field. My mesh is third order, but the error comes ou below, and the other module of FieldConvert works. Fatal : Level 0 assertion violation Variable index out of range. terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError' what(): Level 0 assertion violation Variable index out of range. Could someone give me some advice? With best regards