[samiam1000]

Dear All,

I am trying to use the different tutorial that deals with the chtMultiRegionFoam solver, but I can not find what I am looking for.

I see hot to treat the fluid-solid interface between region, but I can not understand how to treat the solid-solid and the fluid-fluid interface.

Which are the right BC on epsilon, k, U, p, p_rgh, T and so on on these interfaces?

Thanks for help,

Samuele

[anon_a]

I will attempt to answer your question, not because I am sure about the answer but rather to see if I have it right in my mind.

In the chtMultiRegionFoam/multiRegionHeater we can see that all interfaces of the heater with the rest of the parts have the same BC for the temperature:

            "heater_to_.*"
            {
                type            compressible::turbulentTemperatureCoupledBaffleMixed;
                neighbourFieldName T;
                K               solidThermo;
                KName           none;
                value           uniform 300;
            }

Since the heater is a neighbour of both the gas and the solid, I believe this answers your question about solid-solid: you use pretty much the same BC as in solid-gas. If I remember well, this just imposes the same temperature and heat flux on both sides. The rest of the quantities you wrote about (epsilon, k, U, p, p_rgh) do not exist in the solid anyway.

As for the fluid-fluid: why do you have an interface in the first place? Can't you join these two parts? if you can't, you might need significant modifications in the solver.

[samiam1000]

Dear anon_a,

thanks for answering.

Actually, as far as the solid-solid interface is concerned, you're right. It's enough to use the same BC that are used in the tutorial.

Also, I have 2 different fluid region because I would like to be able (but I need to modify the solver and I've not been able, yet) to impose the temperature in a certain FLUID volume, which is connected with another fluid volume. Altough I can't run my new solver, yet, I have a mesh with 2 detached fluid regions, with an interface. I thought that a zeroGradient condition was ok, but that's not true.

The simulation, in fact, seems to explode and it's like a source appear on the interface.

Anyother idea?

Do you think I should `unify the 2 regions'? Can't I deal a domain with to fluid regions detached by an interface?

[Linse]

Hi Samuele,

If it really is just about imposing a different temperature on one of two fluid zones, I suggest using the "setFields" utility. That is much easier than writing a new solver, getting two zones to cooperate easily.

Nevertheless, if you made progress on the fluid-fluid-thingy, I would be happy if you could share your knowledge with me. Because at the moment I am trying to do something very similar. ;-)

[samiam1000]

Dear Bernhard,

of course I will share what I will discover.

And what about the setField? I need to impose temertature, but I need that it remains constant during the whole simulation. I was thinking about explicitSetValue (but it's not implemented in the multi regions solver). That's why I was editing the source.

Can I solve this with the setFields option?

Also, what about writing via email (samuele.zampini@gmail.com)? That would be much easier and we could post something useful if we reach our goal.

Samuele.