## Fluids

#### Results and How To Obtain Outlet or Defined Volume Average Velocity?

• Mecha
Subscriber

Hi,

I have a few questions of my 1st simulation in ANSYS fluent.

Problem Description:

See Figure_1. High compressed air is flowing within the annulus and through the "barrier" with an inlet pressure of 1.7 bar or a flow rate ( 283 L/s = 0.283 m^3/s). What is the average velocity in the outlet?

Fluent Setup:

Figure_2 display the setup and velocity result.

Questions:

Setup 1) The results seems a bit extreme in terms of velocity, validating this with the flow rate: Q = AV --> V = Q/A = 0.283/7.21*10^-4 = 392.5 m/s. Which is far from the inlet simulation. I am not used to simulate high pressurised gases so it may very be that this is realistic or am I missing something?

Setup 2) Same setup but switched the pressure inlet to a mass flow inlet. The values dropped drastically but it seems more realistic than setup 1. Shouldn't the pressure and flow rate correspond to the same results?

How do I obtain average velocity or a defined volume average velocity?

For future questions, Which questions is suitable for posting in Discussion VS Questions?

• Karthik R
Hello In your first case, could you check the overall mass flow rate and compare it with that in your second case? I suspect that there is a difference between the two cases and therefore the results are different.
Karthik
• Mecha
Subscriber
Ah, you made me think! I assumed that the pressure if 1.7 MPa would be the same as 0.283 m^3/s but it seems like its not the same.
That takes me to the original questoin about how I can obtain a measurement of average velocity or a defined volume average velocity in Fluent?

• DrAmine
Ansys Employee
Using Report definitions you can create an average of velocity at a boundary / Cell zone.
• Mecha
Subscriber
Thank you, I think Ive succeded
• Karthik R