Why the outlet pressure is set fixedValue = zero? It should be zeroGradient.
|
2 Attachment(s)
Thank you Sukanta.
I changed the pressure boundary condition as the following: Code:
boundaryField What do you think? Thank you! |
Quote:
Since we use relative scale for pressure, we assume the atmospheric pressure is zero. The outlet is to be set to zero if it is at atmospheric pressure. If you get a pressure below zero, its less than atmospheric pressure. I hope I am correct. |
But why inlet is fixed at zero now? Change in to zeroGradient
You have 30 m/s constant flow. Just tell me one thing if U at inlet is 30 m/s and Pressure is zero in that patch...is it consistent? |
Quote:
But from blockMeshDict I can say there is something wrong with naming the patches. I guess in this case the patches inlet and outlet are swapped. But I am not sure. :) If the inlet is set to some velocity, say 30 m/s, the pressure is set to zeroGradient. Also if the outlet is set to be with a pressure ( fixedValue )of zero , then the inlet should be zeroGradient. I do this in my cases and I get good results |
Quote:
|
Quote:
Hope this helps |
1 Attachment(s)
1. I had to change the inlet condition also because otherwise I got an error which basically said that the solver couldn't find any reference cell for pressure.
2. Pressure is relative, so (I think) you can have 30m/s velocity with 0 pressure because that mean that the pressure s the same as ambient static pressure 3. Inlet and outlet are fine, just checked them in paraview. 4. I ran the simulation for another 1000 iterations and the strange behavior underlined in previous pic disappeared but I'm still getting way too high velocity… |
@lovecraft22
Why is there a zero velocity line (vertical streak of blue)at the inlet? is it due to your boundary conditions? |
its because the velocity = 30 m/s at inlet.
what is the outlet velocity boundary in this case? |
1 Attachment(s)
May be you can have a look at my simulation -> see attached pic
|
2 Attachment(s)
That's my inlet condition: he velocity is not 0 but 30m/s.
About the outlet, the velocity is around 3000 m/s!! It's an hypersonic cylinder! |
what boundary condition you are using for outlet?
Also what pRefValue you are using? |
Quote:
Thank you! |
Try these boundary settings
for pressure inlet { type freestreamPressure; } outlet { type freestreamPressure; } for velocity inlet { type freestream; freestreamValue uniform (30 0 0); } outlet { type freestream; freestreamValue uniform (30 0 0); } |
You have to define one pressure value at least.
I set the pressure value to 0 at the inlet and the rest as you suggested. Now it's running, let's see what comes out. |
Quote:
which solver you use for hypersonic flows? |
I was just kidding about the fact that though I'm running a low velocity simulation yet I get an hypersonic velocity at the outlet…
|
Quote:
Which version of OF are you using? |
OpenFoam 2.0.0
|
All times are GMT -4. The time now is 16:13. |