Hi Sehman, Is this a large mesh? In the XML format we have to read the whole mesh before then selecting a smaller range which has lead to memory issues on large meshes. The hdf mesh format is therefore better and we have recently fixed a bug where only the relevant files are read. In addition if the fld file is in hdf format we can be more efficient in the loading. Hope that helps, Spencer Sent from my iPhone On 3 Feb 2024, at 10:05, Selman BAYSAL <selmanbaysal@comu.edu.tr> wrote:  This email from selmanbaysal@comu.edu.tr 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 try to run the FieldConvert range option in parallel (e.g., mpirun -np FieldConvert -r x1,x2,y1,y2 turb.xml turb.fld turb.plt) it gives the segmentation fault. This post-process takes a long time in serial run. Is there any point I'm missing? Many thanks in advance. Selman Baysal R. A. in Hydraulics Dept. of Civil Eng'g Çanakkale Onsekiz Mart University -- ITU Civil Eng., BSc. ITU Coastal Sci. & Eng., MSc. _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users