Negative Pressure?

courtjester140 · March 17, 2010, 17:51

I have a post open in the meshing/geometry section of the boards. I've finished everything, ran a steady state simulation at 60 mph, k-e turbulence, etc. When I looked at the pressure contour on the surface of the model, at first I thought everything was fine, until I noticed that the legend showed some parts with a negative pressure.

Is this an error that I can fix without too much of a headache? I realized that I need to add inflation layers to my mesh, but without those would a negative pressure occur?

-Michael Petrarca

ghorrocks · March 18, 2010, 06:55

The pressure is relative to your reference pressure. Assuming your reference pressure is 1 bar then you have pressure ranging from approx 99500Pa to 100500Pa absolute.

courtjester140 · March 18, 2010, 14:49

Quote:

Originally Posted by ghorrocks

The pressure is relative to your reference pressure. Assuming your reference pressure is 1 bar then you have pressure ranging from approx 99500Pa to 100500Pa absolute.

Thank you for your reply. I thought that this was a representation of absolute pressure. Lesson learned

.

ghorrocks · March 18, 2010, 16:47

The absolute pressure is also available as a different variable.

taojunhust · August 11, 2011, 23:28

the absolute static pressure of your results will be positive.

March 17, 2010, 17:51	Negative Pressure?	#1
courtjester140 New Member Michael Petrarca Join Date: Apr 2009 Posts: 9 Rep Power: 17	I have a post open in the meshing/geometry section of the boards. I've finished everything, ran a steady state simulation at 60 mph, k-e turbulence, etc. When I looked at the pressure contour on the surface of the model, at first I thought everything was fine, until I noticed that the legend showed some parts with a negative pressure. Is this an error that I can fix without too much of a headache? I realized that I need to add inflation layers to my mesh, but without those would a negative pressure occur? -Michael Petrarca

March 18, 2010, 06:55		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	The pressure is relative to your reference pressure. Assuming your reference pressure is 1 bar then you have pressure ranging from approx 99500Pa to 100500Pa absolute. presidentmamun and Taron like this.

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March 18, 2010, 16:47		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	The absolute pressure is also available as a different variable.

August 11, 2011, 23:28		#5
taojunhust New Member TAO JUN Join Date: Mar 2011 Posts: 3 Rep Power: 15	the absolute static pressure of your results will be positive.