Dear Wang, No problems at all: 1. The incompressible symmetry BCs may only be applied to cases with flat surfaces. Here is an example of a 3D x-z symmetry plane set of conditions: <N VAR="u" VALUE="0"/> <D VAR="v" VALUE="0"/> <N VAR="w" VALUE="0"/> <N VAR="p" VALUE="0"/> 1. I am not quite sure I understand your question. Do you want to reflect around the symmetry plane? Normally I convert the solution to csv, mirror it in Python and interpolate it to a mesh of the complete domain. Is that what you are asking? Thanks, Guglielmo ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of 王舟阳 <wangzhouyang@buaa.edu.cn> Sent: 29 March 2023 17:46 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] About Symmetric Boundary Condition in 3D Simulation This email from wangzhouyang@buaa.edu.cn 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 Nektar++ users and developers: Sorry to bother everyone here, however, I need some help with boundary condition setting in the IncNS solver. My case is a 3D model with xz-symmetric plane: 1. Is there a boundary condition of symmetry surfaces in Nektar++ IncNS solver (such as symmetry boundary in Ansys Fluent), and is there an alternative scheme (if xz-plane is the symmetric plane how could I properly set [u v w p] bc-vector on the y=0 mid-plane? Neumann u=0, Dirichlet v=0, Neumann w=0, Dirichlet p=0?) 2. If there is a boundary condition such as a symmetry surface, whether the flow field of the full-model can be generated from the half-model fld files utilizing the FieldConvert tool. Could it be reliably implemented using pointwise file (calculate the half-mode (if possible), write out the DAT (tecplot) file, write the data symmetrically to a pointwise file, and then write the full-mode mesh)? Thank you for your help and look forward to your discussion and response. Thanks to the Nektar++ project team. Best Regards, Wang Zhouyang