CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM Running, Solving & CFD (
-   -   How to apply a function as boundary condition (

coompressor January 13, 2009 04:48

Dear Foamers, I'm a newbie
Dear Foamers,
I'm a newbie here. For my question, I want to add a function with time and circumferential position as the variables for the inlet boundary condition.
The study object is a circular ring and the inlet radius is R2 while the outlet one is R3. The inlet condition should be V2=V_mean+sin(Omega*t+phi), in which the Omega is the angular velocity and a constant in this expression. V_mean and phi (initial position) are also constants, t is the time for unsteady calculation. Can such kind of boundary condition be given? For fluent, this is very easy through using the UDF.
Thanks all.

vijayakumar January 15, 2009 04:49

i need to run a combustion pro
i need to run a combustion problem.... i used XI-foam as solver, while running some errors are coming... i need to know which solver is good for combustion problem.. and few guidelines for solving combustion problem.

gschaider January 15, 2009 06:07

OK. Let's see: http://openfoam
OK. Let's see:

You hit the points 1,2,3,5 and 7. Not a bad score. But it means it is very unlikely that you'll get an answer. No offense.

coompressor January 15, 2009 06:53

Ok, I'd like to use the DNS so
Ok, I'd like to use the DNS solver in OpenFoam 1.5.
Is this information clear?

ngj January 15, 2009 07:14

Hi Chuang I am certain that
Hi Chuang

I am certain that Bernhard's comment was not minded on you, but on the person who hijacked the thread.

As a answer to your question, I cannot see any spatial variation in your boundary condition, thus you might be able to achieve what you are after by applying "timeVarying<something>". I am not at a OF-machine at the present, but you should be able to find it using the search function.

Best regards


gschaider January 15, 2009 15:47

Hi Chunag! Niels is right.
Hi Chunag!

Niels is right. I meant the other poster. Sorry if I upset you


coompressor January 15, 2009 22:26

Hi, Niels and Bernhard, If
Hi, Niels and Bernhard,
If you plot the function I posted, it has nonuniform distribution along the circumferential direction. for a function, such as sin(n*theta) is a kind of flower function. theta is the circumferential coordinate. I've noticed a poster which talked about parabolic inlet boundary condition. But there do existed some differences. Can anybody give me a hint?

ngj January 18, 2009 16:03

Hi Chuang There is not prob
Hi Chuang

There is not problem in specifying boundary conditions, which are varying both in space and time.

I you want to give a Dirichlet condition, then I would recommend you to find parabolicInlet-BC, which you will be able to find on this forum. This you should be able to modify to the purpose you are considering.

When you have implemented your own conditions just compile the BC using the wmake-procedure, link the BC to the solver of your choice, and you should be well off.

Good luck,


coompressor January 19, 2009 19:45

Hi Niels, Thx for your kin
Hi Niels,
Thx for your kind help! I'll try it and post my results here.

Best Regards,
Chuang Gao

andrea February 12, 2009 11:22

Hi everybody, I'm dealing wit
Hi everybody,
I'm dealing with boundary condition as function of a calculated scalar fields. I think to derive it from a fixedValue bc. Someone have already done something similar?

All times are GMT -4. The time now is 20:28.