simpleFoam - setting the pref value

ufocfd · November 6, 2016, 07:38

I have been running simpleFoam for flow analysis over a car and initially set pref = 101325 (in the fvSolution file) which was giving quite large forces when integrating the surface pressure over a car body.

I then changed pref=0 and re-ran the same case, giving significantly lower force values (and more realistic CL & CD), when integrating the surface pressure on vehicle.

Think it maybe be related to the surface pressure integration method in Paraview.

anishtain4 · November 9, 2016, 14:34

When you're solving incompressible flow the absolute pressure is not important, it's just the gradient (even when integrating an immersed surface such as a car body). If your solutions are correct velocity profiles should be reasonable.

November 6, 2016, 07:38	simpleFoam - setting the pref value	#1
ufocfd Senior Member Giles Richardson Join Date: Jun 2012 Location: Cambs UK Posts: 115 Rep Power: 15	I have been running simpleFoam for flow analysis over a car and initially set pref = 101325 (in the fvSolution file) which was giving quite large forces when integrating the surface pressure over a car body. I then changed pref=0 and re-ran the same case, giving significantly lower force values (and more realistic CL & CD), when integrating the surface pressure on vehicle. Think it maybe be related to the surface pressure integration method in Paraview. Last edited by ufocfd; November 6, 2016 at 15:55.

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November 9, 2016, 14:34		#2
anishtain4 Senior Member Mahdi Hosseinali Join Date: Apr 2009 Location: NB, Canada Posts: 273 Rep Power: 19	When you're solving incompressible flow the absolute pressure is not important, it's just the gradient (even when integrating an immersed surface such as a car body). If your solutions are correct velocity profiles should be reasonable.