different pressures in CFX-Post
 

Hi CFX user, in the compressible flow simulation there are three pressures in the CFX-Post, Absolute Pressure, Pressure and Total pressure. Can anyone tell me what the diffence is? Which pressure is used as the static pressure? thanx in advance Regards

Re: different pressures in CFX-Post
 

Pressure = Static Pressure - Reference Pressure Absolute Pressure = Static Pressure + Reference Pressure

Re: different pressures in CFX-Post
 

Total Pressure = Static Pressure + Dynamic Pressure

I.e. it is the Stagnation Pressure

Re: different pressures in CFX-Post
 

Are you sure Cyclone that in CFX-Post Total Pressure= static pressure + dynamic pressure? Isn't it Total Pressure=static pressure+dynamic pressure-Pref?

(I know that your definition is the right one, but I think that CFX-post is internaly changing the definition, 'cause if you plot pressure and total pressure over a wall surface you find the same...)

Let me know if you think I'm wrong, because it's something that I have only noticed by myself...

Re: different pressures in CFX-Post
 

Sorry, you're right. It is reported relative to the domain reference pressure.

At a wall, the velocity is zero, so the dynamic pressure is zero and thus the total pressure is equal to the static pressure.

-CycLone

Hi!
In CFD-Post I can only choose between "pressure" and "total pressure" to be shown on my plane.
I need the "static pressure", so I have to choose "pressure"?

Am I right?

Pressure is the static pressure. Note it has the hydrostatic component removed, if that is relevant. See the documentation for more information.

Is it possible to draw dynamic pressure directly in Ansys CFX ?
Because I can draw the figures whic can show the distrubition of the static pressure and total pressure, but I wanna see the distrubition of the dynamic pressure.

If you can explain how it can be possible, I would be very gratefull.

Define a variable with an expression Total Pressure - Pressure. Then it is a variable you can do anything you like with.