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-   -   The simplest way to shut off the flow in a pipe (https://www.cfd-online.com/Forums/openfoam-solving/224162-simplest-way-shut-off-flow-pipe.html)

miotto February 9, 2020 11:19

The simplest way to shut off the flow in a pipe
 
In my model I would like to block the flow in a pipe at a specific time. What is the simplest way to do this?


I don't need the realistic behavior of a valve here. An instantaneous shut off would be enough.

HPE February 9, 2020 12:00

bro, your question is very broad, I think, for anyone would help you.

miotto February 9, 2020 12:31

Hey, bro, sorry about that. I'm totally new to CFD and OpenFOAM.
Let me try again


Lets suppose I have a "2D" model made of just one block. This block being divided into x cells in the i direction and y cells in the j direction. Now lets suppose that the left face of left most cells is the inlet with (with p=p_in) and the right face of right most cell is the outlet (with p=p_out). All the other boundary conditions are walls. Assume p_in > p_out and we have flow. So far so good, this I can do.
But what if at a specific time t_shut, I need to block this flux in certain point of the model. Say, right in the middle (i=x/2), how can I do that? Can I use some kind of baffle? If yes, how can I make it appear just at t=t_shut?

LuckyTran February 10, 2020 13:18

I would change a boundary condition and not try to force a stop in the interior domain. You can just change the boundary condition type at the right outlet into a wall.


1)Run your case up to the shutoff time. You should now have a case with a time dir at the shutoff time, say 3.14159. If not, then change the appropriate settings in controlDict so that you do.
2) Now change the BC type in the 3.14159 time dir. You can use the changeDictionary utility or you can do it manually with a text editor by editing the p, U, etc. file.
3) Run the case starting now from the shutoff time to whatever time.

miotto February 11, 2020 08:39

Quote:

Originally Posted by LuckyTran (Post 757579)
I would change a boundary condition and not try to force a stop in the interior domain. You can just change the boundary condition type at the right outlet into a wall.


1)Run your case up to the shutoff time. You should now have a case with a time dir at the shutoff time, say 3.14159. If not, then change the appropriate settings in controlDict so that you do.
2) Now change the BC type in the 3.14159 time dir. You can use the changeDictionary utility or you can do it manually with a text editor by editing the p, U, etc. file.
3) Run the case starting now from the shutoff time to whatever time.


Thank you for the instructive reply, LuckyTran.
Nevertheless, shutting off the right outlet wont work for me, because the phenomena I want to observe is indeed downstream to the valve.
Any ideas?


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