|August 26, 2015, 10:54||
pressure force calculation in compressible solvers
Join Date: Jun 2014
Posts: 10Rep Power: 3
I wish you a sunny and happy day! :-)
I am trying to understand the way OpenFOAM calculates the pressure force via the function "forces". This topic has already been enlightened partially by the following post:
Pressure force calculation in incompressible solvers
Unfortunately, it is only for incompressible solvers. Now, I would like to extend my understanding to compressible flows.
I found the lines of code in forces.c where e.g. the pressure force is being calculated:
I then tried to understand the role of pRef. I came that far (incomp+comp):
if one of the BC for p are fixedValue then pRef does not come into effect. But, when I don't specify a fixedValue the solver takes the pRefValue defined in fvSolution.
Please correct me, if I am wrong, so far.
My questions are:
1) Why is pRef subtracted? In my understanding it would make more sense to add it to p...
2) Why is pRef in the formula used in the compressible case? Isn't p already in absolute readings? Please enlighten me.
3) How does the direction come into play (it is defined as a vectorField...)? I guess that information has to be in Sfb. Please help me to understand this.
I am already looking forward to your answers. Sorry, for stealing your time on such a sunny day... :-)
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