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-   -   Starting pimpleFoam computation from simpleFoam result (http://www.cfd-online.com/Forums/openfoam-solving/109759-starting-pimplefoam-computation-simplefoam-result.html)

vinz November 26, 2012 05:25

Starting pimpleFoam computation from simpleFoam result
 
Dear all

Here is what I am doing.
I did a first computation using simpleFoam on a "empty" shape that you can see in the picture below.
http://www.cfd-online.com/Forums/att...efinaltime.png

Up to that point everything is fine and results look good.
My goal is to place a valve on the right part of the shape with an overpressure inside. To do that I created a new mesh, I chose a pressure of 500 Pa in all the field and then I used mapFields with the precedent result. This way, the pressure is equal to 500 inside the shape and is equal to the previous result everywhere else. (See picture below).
http://www.cfd-online.com/Forums/att...nitialtime.png
http://www.cfd-online.com/Forums/att...sult-valve.jpg

Then I want to start my computation with pimpleFoam with still the same wind coming from the right (4m/s) in order to see if my over pressure actually decreases through the valve and what the flow looks like in this part.

My problem here is that at the first time step the pressure in the shape becomes quickly equal to the "stagnation" pressure I found in my previous computation. Without really creating any flow through the valve. Even for low timeSteps, the behavior does not look correct.

I already ran some computations with non uniform initial flow field using rhoPimpleFoam with quite good results but with this case I don't manage to get what I want.
I have to add that my computation is axisymmetric.

Does anyone have an idea on this ?

Vincent

vinz November 29, 2012 06:13

any idea on what's going on?

michielm November 29, 2012 06:27

The images are not visible. Could you post them through the image include of the forum?!

vinz November 29, 2012 06:45

Thank you for pointing that out.

It is actually very strange since I can see the image on linux but not on my Mac.

Here are the links toward images, and as you can see I have use the forum attachment tool since they are hosted on CFD-online:
http://www.cfd-online.com/Forums/att...1&d=1353921281
http://www.cfd-online.com/Forums/att...1&d=1353921281

http://www.cfd-online.com/Forums/att...1&d=1353921472
http://www.cfd-online.com/Forums/att...1&d=1353921472

http://www.cfd-online.com/Forums/att...1&d=1353921481
http://www.cfd-online.com/Forums/att...1&d=1353921481

michielm November 29, 2012 06:52

Quote:

Originally Posted by vinz (Post 394834)
Thank you for pointing that out.

It is actually very strange since I can see the image on linux but not on my Mac.

Here are the links toward images, and as you can see I have use the forum attachment tool since they are hosted on CFD-online:
http://www.cfd-online.com/Forums/att...1&d=1353921281
http://www.cfd-online.com/Forums/att...1&d=1353921281

http://www.cfd-online.com/Forums/att...1&d=1353921472
http://www.cfd-online.com/Forums/att...1&d=1353921472

http://www.cfd-online.com/Forums/att...1&d=1353921481
http://www.cfd-online.com/Forums/att...1&d=1353921481

Still can't see them. I get this message: 'Invalid Attachment specified. If you followed a valid link, please notify the administrator'

Do you have any external place to put them so I can look at them there?

vinz November 29, 2012 06:58

3 Attachment(s)
let's try it for the last time.

Now normally it should be even visible on the first message.

michielm November 29, 2012 10:04

Yes, now I can see the images.

I'm not sure why this would happen. What boundary conditions do you have on the valve walls?!

vinz November 29, 2012 10:21

I treat them as no slip walls.

vinz December 10, 2012 03:18

I am really stuck with this.

Does anyone have any idea?

vut March 17, 2014 13:35

Initialize pimpleFoam from simpleFoam solution
 
Dear VINZ,

Your post interested me.

I am new Foamer with little experience and I am searching for initializing a LES simulation using pimpleFoam from a solution of simpleFoam.

That's would be great if you can give me some details and steps to follow.

Thank you in advance,

VUT


Quote:

Originally Posted by vinz (Post 394157)
Dear all

Here is what I am doing.
I did a first computation using simpleFoam on a "empty" shape that you can see in the picture below.
http://www.cfd-online.com/Forums/att...efinaltime.png

Up to that point everything is fine and results look good.
My goal is to place a valve on the right part of the shape with an overpressure inside. To do that I created a new mesh, I chose a pressure of 500 Pa in all the field and then I used mapFields with the precedent result. This way, the pressure is equal to 500 inside the shape and is equal to the previous result everywhere else. (See picture below).
http://www.cfd-online.com/Forums/att...nitialtime.png
http://www.cfd-online.com/Forums/att...sult-valve.jpg

Then I want to start my computation with pimpleFoam with still the same wind coming from the right (4m/s) in order to see if my over pressure actually decreases through the valve and what the flow looks like in this part.

My problem here is that at the first time step the pressure in the shape becomes quickly equal to the "stagnation" pressure I found in my previous computation. Without really creating any flow through the valve. Even for low timeSteps, the behavior does not look correct.

I already ran some computations with non uniform initial flow field using rhoPimpleFoam with quite good results but with this case I don't manage to get what I want.
I have to add that my computation is axisymmetric.

Does anyone have an idea on this ?

Vincent



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