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Old   March 13, 2008, 11:38
Default Negative Total Pressure
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Here I am again...

In a simulation I found a negative total pressure in a contour plot... Anybody can explain me how it is possible???


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Old   March 14, 2008, 11:28
Default Re: Negative Total Pressure
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The Total Pressure (aka Stagnation Pressure) is reported relative to your domain reference pressure. Don't confuse it with Absolute Pressure, which is the static pressure + relative pressure.

Also, if you fluid is incompressible, any pressure is possible. If fluid properties are not dependant on pressure, then all pressures are relative (i.e. if you add the same pressure, say Poffset, to all your boundary conditions, the solution is the same, but the pressure is offest).

In reality you don't have negative pressures because density changes with pressure in a gas and liquids boil/cavitate when the pressure is low enough. If you include this behavior in your model, you won't see negative pressures.

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Old   April 5, 2008, 07:24
Default Re: Negative Total Pressure
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hi i am also faced same problam i give inlet mass flow==1kg/sec and static pressure= 8bar outlet avrage static pressure= 3bar i given. but when ever i seen post results plot is comming nearly 20 bat comming. how is rectifying. please give me responce thanking you bye

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