okay, the Womersley solution validation
 

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 http://openfoamwiki.net/images/math/...0bab4045ce.png

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

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?

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