Learning Forum

[harishkamath86]

hii,

in this image, as mentioned, I have to apply zero pressure on four faces and on the top face, I have to apply rotational speed of 2000 rpm. but facing a problem with this. kindly help to apply boundary conditions for my CFD analysis. what are the boundary conditions I have to apply to solve this?. Thank you.

kindly help

 

[Rob]

Try setting the motion on the fluid cell zone and then use pressure boundaries. I assume you mean zero gauge pressure? What's the ambient pressure?

[harishkamath86]

Thank you for your kind reply sir. 

Sir, you are right. I want to apply zero gauge pressure on all the four faces of fluid and rotation for the top layer of the fluid face. 

rotation I am able to give on the top face but I don't know how to apply zero gauge pressure to those four faces. 

Sir, what kind of pressure boundaries I have to apply? pressure inlet and pressure outlet on four faces ??

Sir, I need to get pressure results like this, as per the boundary conditions mentioned earlier 

thank you

kindly reply

[DrAmine]

Are the 4 faces areas where flow might enter or exit? Or walls?

[harishkamath86]

enter from only one face and exit from opposite side face. to be specific, enter from the left side and move towards the right side

 

if all four faces are specified as "wall" then whether gauge pressure will be zero ?? 

thank you

[DrAmine]

No: with walls it won't work the way you want.
Now why does enter from one side and leave from particular side?

[harishkamath86]

Dear Amine Sir, Kindly excuse for the last message.

( Sorry for the last message where I said it enters from one end and leaves from other)

As per the published literature, actually fluid is restricted to stay within that confined boundary. It builds-up pressure on the solid body which is present below it. 

Sir, neither fluid leaves from any of the sides nor enter.

Sorry again.

Thank you

 

[DrAmine]

Then walls. Read carefully the paper as at walls you cannot provide pressure information.

[harishkamath86]

Dear Amine Sir,

if I specify "Walls" as BCs then I am getting wrong results. I am getting pressure variations at the boundary of the fluid. I am not supposed to get pressure variations near the boundary.

Finding difficult to solve this.

Sir, any other solution?

Thank you for kind reply

[DrAmine]

No I do not have any other solutions. The only one quick thing is using pressure outlet with zero absolute pressure there but this might allow flow getting out of these boundaries.