[al_th]

Hi,

I am looking at a boundary condition that would let me switch between a cyclic (periodic) boundary condition and a wall boundary condition.

I found that I can use groovyBC (and swak4foam) to implement basic if/else conditions based on field values. What bothers me is the following sentence :

It is very important to note, that no form of patch-to-patch interpolation of the fields is performed. If the number of faces on the local and remote patches are not identical, entire fields cannot be mirrored from remote patches to local patches.

If my two patches are identical (I created the two patches using createBaffles that basically gives me a master and a slave patch with exactly the same number of cells), does this mean that I can ACTUALLY mirror pressures, velocities and everything else ?

In the case that groovyBC is not adapted to my problem, do you know any other BC that could be appropriate ? Or should I reimplement the BC by mixing cyclic and wall (I assume this is doable).

Best regards,

Al_th

[roadRunner]

I'm not sure if I understood your question correctly, you can define different boundary conditions for different fields, if that is what you want.
So AFAI understand, you should be able to use cyclic for pressure and fixed value for velocity (but I don't see how is that useful).

e: oh, now I see that you want conditional BC

[al_th]

Dear roadRunner,

Yes, what I want is conditional boundary conditions. Specifically, I want to be able to control my boundary conditions through time or depending on specific values of my fields (pressure gradients, current local velocity, ect).

Any appropriate boundary conditions ?

Best regards,

al_th

[Majed]

Hello al_th

Have you had any success in implementing such a BC?

Best regards,

Hessam

[al_th]

Originally Posted by Majed

Hello al_th

Have you had any success in implementing such a BC?

Best regards,

Hessam

Hi Hessam,

I am sorry to tell you that I did not directly implemented the BC. Specifically because I'm an OpenFoam newbie and I was not quite sure how I could bind them as even the base type of the two are not the same (http://cfd.direct/openfoam/user-guide/boundaries/).

However, I succeeded in doing what I wanted using an alternative tricky route.

First, using the "timing" method, I used the controlDict file to set up my timer, stop the simulation when I needed to change the BC, and relaunched it with the proper boundary condition with a script as if you were starting a new simulation except your fields are not 0 anymore.

The second thing I needed was to open or close a wall depending on the field itself. What I did is the following :

In the *.cpp file of my solver, I wrote a little piece of code that look at the values I need, and if it reaches my stop condition : write a file and stop the simulation. In my launching script, if I detect this file, I switch my boundary conditions and restart the simulation.

This is more complicated than my initial request, but it works for what I do.

[tguozden]

Hello roadRunner, I am trying to solve a case in which I have cyclic boundary conditions for velocity and impose values to pressure. But I am forced to define the cyclic condition already in the blockMeshDict. How can I avoid this step?

Thanks,

Tomás.-

Originally Posted by roadRunner

I'm not sure if I understood your question correctly, you can define different boundary conditions for different fields, if that is what you want.
So AFAI understand, you should be able to use cyclic for pressure and fixed value for velocity (but I don't see how is that useful).

e: oh, now I see that you want conditional BC

[FlameSlave]

Originally Posted by tguozden

Hello roadRunner, I am trying to solve a case in which I have cyclic boundary conditions for velocity and impose values to pressure. But I am forced to define the cyclic condition already in the blockMeshDict. How can I avoid this step?

Thanks,

Tomás.-

I am trying to do something similar. I want to impose cyclic boundary conditions for the flow field but fixedValue on two patches in a box for an external electric potential. Any idea how to approach this?