# Boundary condition including time derivative

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 June 20, 2015, 10:35 Boundary condition including time derivative #1 New Member     Ender Demirel Join Date: Jun 2009 Location: Turkey Posts: 16 Rep Power: 10 Sponsored Links Hello OF users, I want to implement a Neumann type boundary condition for the pressure as follows dp/dx=-p-dp/dt. Does anyody know how to use this bc in OpenFoam or swak4Foam? Best regards, Ender

 June 20, 2015, 10:37 #2 Senior Member   Alex Join Date: Oct 2013 Posts: 334 Rep Power: 14 This is a fixed gradient BC __________________ Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

June 20, 2015, 10:44
#3
New Member

Ender Demirel
Join Date: Jun 2009
Location: Turkey
Posts: 16
Rep Power: 10
Quote:
Boundary condition depends on the first order time derivative of the pressure. I don't know how to use this time derivative term in the expression.

 June 20, 2015, 14:02 #4 Senior Member   Alex Join Date: Oct 2013 Posts: 334 Rep Power: 14 Forget about what I said in the last post, fixedGradient can't be used to suit your needs, I missunderstood the term Neumann you used... However, it can be achieved by using swak4foam and using the value for pressure from the last time step and the current one. Best regards, Alex __________________ Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

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