okay, the Womersley solution validation

nobound · March 7, 2011, 23:46

nobody answers my last post. So I think I need to ask my question in another way.

I think people in this community already did validation against the theoritical solution a lot before.

My question is this:

I have a velocity inlet V(t)=cos(t), I use icoFoam as the solver, (as in the cavity tutorial), but I need to change the BC from constant inlet velocity to varying bc. How to do it then?

One answer I found online is oscillatingFixedValue:

http://openfoamwiki.net/index.php/Ma...tingFixedValue

But after checking the result, i do not think it is pure oscilating, instead, it is a function of sine together with a steady positive flow rate.

like

if I delete 1 from the above formular, there is simly no flow then.

I want a flow with back flow at some time steps.

Anybody knows what is wrong? or any other function instead of oscillatingFixedValue?

Thanks

Bernhard · March 8, 2011, 02:42

Why are you applying this BC in the cavity, and not in pipe, or duct flow, as one would expect? What are your outflow boundary conditions?

nobound · March 8, 2011, 12:09

it is a 3d pipe, the outlet BC is pressure is zero.

March 7, 2011, 23:46	okay, the Womersley solution validation	#1
nobound New Member Join Date: Feb 2011 Posts: 3 Rep Power: 15	nobody answers my last post. So I think I need to ask my question in another way. I think people in this community already did validation against the theoritical solution a lot before. My question is this: I have a velocity inlet V(t)=cos(t), I use icoFoam as the solver, (as in the cavity tutorial), but I need to change the BC from constant inlet velocity to varying bc. How to do it then? One answer I found online is oscillatingFixedValue: http://openfoamwiki.net/index.php/Ma...tingFixedValue But after checking the result, i do not think it is pure oscilating, instead, it is a function of sine together with a steady positive flow rate. like if I delete 1 from the above formular, there is simly no flow then. I want a flow with back flow at some time steps. Anybody knows what is wrong? or any other function instead of oscillatingFixedValue? Thanks Last edited by nobound; March 8, 2011 at 12:11.

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March 8, 2011, 02:42		#2
Bernhard Senior Member Bernhard Join Date: Sep 2009 Location: Delft Posts: 790 Rep Power: 21	Why are you applying this BC in the cavity, and not in pipe, or duct flow, as one would expect? What are your outflow boundary conditions?

March 8, 2011, 12:09		#3
nobound New Member Join Date: Feb 2011 Posts: 3 Rep Power: 15	it is a 3d pipe, the outlet BC is pressure is zero.