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Ledeniso June 6, 2013 13:01

Pressure drop in openfoam
Good evening,
i am new here and this is my first post.
I would like to simulate a pressure drop in a flow but i dont really know how to do it
I've tried to do that with a fan like in the tutorial TJunctionFan. So combine tjunction and pitzDaily, but i do not really understand what the patches the baffles abd so on is...( i still red a lot on the openfoam website an on the web, but nothing is clearly explained)
So i tried another solution, i tried to do my own solver with my own geometry but its remains very complicate...
How can i work efficiently with openfoam, what are the first things to know before starting with my simulation

thank you

Lieven June 6, 2013 17:53

Hi Ledeniso,

Welcome to the forum! First of all, can you give a little bit more information about your case? A few things that immediately cross my mind:
* incompressible/compressible
* laminar/turbulent
* isothermal?
* Why would you need your 'own solver'?
* What do you mean exactly by 'work efficiently with OF'? I can give you a lot of advice, but the best place to start is here:



Ledeniso June 6, 2013 18:18

thanks to you Lieven,
my case consist to simulate a flow throught a porous wall in the middle of the flow.
my first idea was to simulate a flow in a pipe with a pressure drop where the porous wall has to be.
In order to reach that goal, ilooked for tutorials which match at the best to my case, but all the tutorial are so various and complicate to understand and so on...
To simulate a pressure drop in a flow i choose the case TJunctionFan ( with the fan to decrese my pressure,
to simulate the flow, i choose the pitzDaily case flow.

So the goal was to combine Tjunction with pitzDaily, but it's doesn"t work at all, i have tried a lot of solution without succes.
That's why i through perhaps it's better to create my own solver with all the boundary condition i need, but it seems to be mission impossible

How can i lose problem in Openfoam, do i do this with the tutorials given while the installation?
the flow is laminar and incompressible.

Thanks again for your answers and sorry for my english.

Lieven June 7, 2013 09:35

Hi Leden,

Why don't you start from the porousSimpleFoam solver?

Regarding the tutorials, don't expect to be able to learn to work with openfoam and all it's applications/tools/tricks/... in a few weeks. That's just not possible for any normal human being. First go through the tutorials explained in the manual, afterwards switch to the one closest to the case you want to simulate.

My apologies, but I don't understand the sentence "How can i lose problem in Openfoam, do i do this with the tutorials given while the installation?"



Ledeniso June 10, 2013 02:23

Hi lieven
I'm going to start learn about the porousSimpleFoam solver this week, and i will try like you advised it to me, to modify it in order to have something that matchs with my case.

with the sentence, i mean are the tutorials the only way to lose problems in OpenFOAM or does it exist anys else tutorial to learn more about OpenFOAM?

I am thanking you so much for your anszer, and i will inform you of my advance.

Lieven June 10, 2013 11:59

Hi Ledeniso,

I think the tutorials are the best place to start. If you search the web or this forum a bit, you can find some additional ones. Depending on how far you need to go, you can also search for 'programming tutorials'. And this forum is definitely also a huge source of input for new OpenFOAM users (and also for the more experienced ones ;-)).

Of course, there are also the OpenFOAM training sessions organized by ESI but I have no experience with those.



mohammad81 July 16, 2013 02:52

Hi dear Foamers,
I would be grateful if you could help me in my problem.
I am new to OF, so forgive me for my simple questions which may seem absolutely trivial to you.
I want to model a 2D channel in which the driving force is pressure gradient. Sounds simple, but I do not know how to do it.
I want to use cyclic BC for both U and P. I studied about cyclic and fan BC and other stuff.
I could solve the problem with cyclic BC for both U and P while the upper wall is moving (like cavity problem), and I used icoFoam.
But I do not know how to do it for pressure gradient case?
what solver shall I use? I know in the forum people said that channelFoam is a good one, but you know that in OF2.2.1 it is removed. shall I use pimpleFoam? or simpleFoam? or icofoam?
please notice that my flow is laminar.
How may I apply the pressure gradient?
How may I apply the cyclic BC?
Thank so much for your time.

Lieven July 17, 2013 07:38

Hi Mohammad,

You can use the fvOptions of OpenFOAM 2.2.x named pressureGradientExplicitSource. This replaces the functionallity of the channelFoam solver (hence it is removed from OF 2.2). As far as I understand, you can use this in combination with any of your preferred solvers. If your flow is laminar, icoFoam or pisoFoam will do the trick.

Applying the cyclic BC is really simple, just set the boundary conditions of the corresponding patches to 'cyclic' for all of the variables.

Hope this clarifies this, if I forgot the mention something, just ask again :-).



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