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Using both pressure point and outlet with Pressure, no viscous stress?

Posted Mar 11, 2013, 4:50 a.m. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.3 1 Reply

Robin Wegner
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Hi!

I'm working with natural and forced convection with the aim to design a ventilation/heating system for my master's thesis.

I'm wondering if I need a "Pressure Point Constraint" if I'm using an outlet with "Pressure, no viscous stress" or if they will cause trouble for each other?

Thanks!
1 Reply Last Post Mar 11, 2013, 3:51 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Mar 11, 2013, 3:51 p.m. EDT
Hi

pressure use is mostly a "gauge" pressure, hence if you have set p=0 at outlet you have given a fixed value to make the solution unique, so no need to add anyother "p" point value, except if it makes sens for your model.

As p is a dependent variable in CFD and it is obtained by integration you MUST define some fixed P somewhere, either implicit or explicit, else you do not have an unique solution

Check also carefully the pA absolute pressure and how that is defined in the main physics nodes (+ the doc)

--
Good luck
Ivar
Hi pressure use is mostly a "gauge" pressure, hence if you have set p=0 at outlet you have given a fixed value to make the solution unique, so no need to add anyother "p" point value, except if it makes sens for your model. As p is a dependent variable in CFD and it is obtained by integration you MUST define some fixed P somewhere, either implicit or explicit, else you do not have an unique solution Check also carefully the pA absolute pressure and how that is defined in the main physics nodes (+ the doc) -- Good luck Ivar

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