Hi Krzysztof,
Nektar++ doesn't enforce incompressibility exactly in the Velocity Correction Scheme. It's chosen like this in the splitting error. You can check that with any run you already have and the postprocessing utility FieldConvert to get the divergence of your field.
FieldConvert -m divergence mesh.xml field.fld field_div.fld
Hopefully if the constant in front is not very big it should be of the order of TimeStep^ORDERSCHEME.
With regards to the pressure BCs, the components of the velocity that appear in the equation are extrapolated as well, so expect another O(TimeStep^ORDER) from there again.
I am not sure whether this solves your concerns,
Best,
From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Michałowski Krzysztof (STUD) <krzysztof.michalowski.stud@pw.edu.pl>
Sent: 14 October 2025 12:32
To: nektar-users <nektar-users@imperial.ac.uk>
Subject: [Nektar-users] Pressure boundary conditions for velocity correction scheme
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Hello,
I am a student at Warsaw University of Technology and I will be using Nektar++ for my masters thesis. I have a question about pressure boundary conditions for velocity correction scheme. To ask this question i had to write down some formulas that is why it
was more conviniant to attache it to this message as a pdf document.
Best Regards,
Krzysztof Michałowski