[Cartuns11]

Hello everybody,

I'm working on a complex model but firstly I've carried out a simple model due to the problems found in the big model.

Currently, I use two "very very simple" models. The first model consists of two cubes with the same fluid but each cube is a different region (cubes2.png). And the second is the same geometry but with one prism (prism.png), which will be used to compare the results obtained with 1 or 2 regions.(prismT.png)

The target is to get the same results on both models.

I want the interface between regions to have a mass flow exchange (exch.png). The boundary is "mappedWall" (left_to_right and Right) type and I don't know how to define de BC.....U, p_rgh and T.

I'm using 2.4.0 and the chtMultiregionSimpleFoam solver. The massFlow model is in this post.

I have some ideas, for example mappedFlowRate or mapped......and also the cyclicAMI but this doesn't work with multiregion....
Using the mapped philosophy, I've obtained info in the "/combustion/fireFoam/les/oppositeBurningPlanels" tutorial. However it doesn't work in my model.

could you help me?

Thanks

[WildeCat]

Hi Cartuns,

I am working on quite a similar problem as you did one and a half year ago. I need to couple the mass transfer between two fluid regions with a boundary condition. I have been looking into mappedFlowRate and other mapped boundary conditions. However without too much success so far. Currently my thought is to rewrite the thermal boundary condition turbulentTemperatureCoupledBaffleMixed to achieve my my goal.
I would like to know whether you managed to solve the problem and could assist me.

For the coupling of the temperature, you can simply use the turbulentTemperatureCoupledBaffleMixed boundary condition in the following form

    <patchName>     
{
         type            compressible::turbulentTemperatureCoupledBaffleMixed;
         Tnbr            T; // neighbouring field
         kappa           lookup; // fluidThermo, solidThermo
         kappaName       kappa;
         thicknessLayers (0.1 0.2 0.3 0.4); // optional
         kappaLayers     (1 2 3 4); // optional
         value           uniform 300; // placeholder     
}

more information on:
http://cpp.openfoam.org/v4/a02795.html

I know I am very late, but maybe it helps someone else in the future.

Thanks in advance
Max

[WildeCat]

Hello everyone,

I would like to give an update for all people who are attempting to couple to fluid regions.

Two way temperature coupling can be achieved with the thermal boundary conditions. Many different exist. More information can be found on:

http://openfoam.org/release/2-3-0/thermal/

Apart from temperature, in some cases it is necessary to couple also other variables such as rho, U or p. In these cases, as far as I know, no two way coupling exists. If however you know that you only need to transfer information from one region to the other, so not coupling it, you can use mappedField. This boundary condition allows to map the conditions at one patch to another patch on different regions. The source guide may help you to understand this boundary condition better.

http://cpp.openfoam.org/v4/a01446.html

Since the source guide is for OF4.x, but I use OF2.3.x, where it is implemented somewhat differently, I will add here how to implement this boundary condition. Make sure the interface between the regions is a mappedWall.

    <interfacePatchName>
    {
        type                  mappedField;
        sampleMode      nearestPatchFace;
        sampleRegion    <neighbourRegion>;
        samplePatch      <interfacePatchNameOnOtherRegion>;
        fieldName          <vairable>; // scalar or vector
        setAverage        no;
        average             (0 0 0); // 0 for scalar
        value                 uniform (0 0 0); // placeholder, 0 for scalar
    }

I am currently working on writing two way coupling between different regions for U. Depending on my case I may be able to solve it differently, but should i find a suitable solution, I'll try to post it here.

Hope I could help

[junxian11]

Originally Posted by WildeCat

Hello everyone,

I would like to give an update for all people who are attempting to couple to fluid regions.

Two way temperature coupling can be achieved with the thermal boundary conditions. Many different exist. More information can be found on:

http://openfoam.org/release/2-3-0/thermal/

Apart from temperature, in some cases it is necessary to couple also other variables such as rho, U or p. In these cases, as far as I know, no two way coupling exists. If however you know that you only need to transfer information from one region to the other, so not coupling it, you can use mappedField. This boundary condition allows to map the conditions at one patch to another patch on different regions. The source guide may help you to understand this boundary condition better.

http://cpp.openfoam.org/v4/a01446.html

Since the source guide is for OF4.x, but I use OF2.3.x, where it is implemented somewhat differently, I will add here how to implement this boundary condition. Make sure the interface between the regions is a mappedWall.

    <interfacePatchName>
    {
        type                  mappedField;
        sampleMode      nearestPatchFace;
        sampleRegion    <neighbourRegion>;
        samplePatch      <interfacePatchNameOnOtherRegion>;
        fieldName          <vairable>; // scalar or vector
        setAverage        no;
        average             (0 0 0); // 0 for scalar
        value                 uniform (0 0 0); // placeholder, 0 for scalar
    }

I am currently working on writing two way coupling between different regions for U. Depending on my case I may be able to solve it differently, but should i find a suitable solution, I'll try to post it here.

Hope I could help

Hi, thanks for your reply. I am coping with two way coupling between different regions for U and p. I want to know do you have some progress now? I am going to die, struggling for this...

[kanchajiaxie]

Originally Posted by WildeCat

Hello everyone,

I would like to give an update for all people who are attempting to couple to fluid regions.

Two way temperature coupling can be achieved with the thermal boundary conditions. Many different exist. More information can be found on:

http://openfoam.org/release/2-3-0/thermal/

Apart from temperature, in some cases it is necessary to couple also other variables such as rho, U or p. In these cases, as far as I know, no two way coupling exists. If however you know that you only need to transfer information from one region to the other, so not coupling it, you can use mappedField. This boundary condition allows to map the conditions at one patch to another patch on different regions. The source guide may help you to understand this boundary condition better.

http://cpp.openfoam.org/v4/a01446.html

Since the source guide is for OF4.x, but I use OF2.3.x, where it is implemented somewhat differently, I will add here how to implement this boundary condition. Make sure the interface between the regions is a mappedWall.

    <interfacePatchName>
    {
        type                  mappedField;
        sampleMode      nearestPatchFace;
        sampleRegion    <neighbourRegion>;
        samplePatch      <interfacePatchNameOnOtherRegion>;
        fieldName          <vairable>; // scalar or vector
        setAverage        no;
        average             (0 0 0); // 0 for scalar
        value                 uniform (0 0 0); // placeholder, 0 for scalar
    }

I am currently working on writing two way coupling between different regions for U. Depending on my case I may be able to solve it differently, but should i find a suitable solution, I'll try to post it here.

Hope I could help

Have you finished and validated the boudary for coupling velocity field? If so. could you please show us some suggestions about this boundary? We are struggling on this and hoping for your help.

[Bernd_77]

Hello everyone,

I am reviving this old thread to also ask whether anyone has made any progress on the two-way coupling between different regions. It seems like many people would be interested in such a boundary condition. I thought I would ask here first before I attempt to program a custom boundary condition with my limited C++ skills...

Thanks for your help
Bernd

[edaymo]

Hello,

I am a co-author on a paper where we describe boundary conditions for region coupling flows with OpenFOAM. This may describe what you are looking for.

Please see https://doi.org/10.1016/j.cep.2019.107728.

I hope this is helpful. For detailed questions, please feel free to contact the lead author, Matthias Hettel (contact information is at the doi URL above).

Best regards,

Eric

[Bernd_77]

Hi Eric,

Thank you for your response, it is a really interesting paper! I will probably contact Matthias Hettel to see if I can have a look at the custom code. Unfortunately my problem is different in that I need to do two-way mapping of a single variable. In your solution, the mapping is in one direction (u is mapped always from Domain 1 to Domain 2 and p is mapped from Domain 2 to 1). For a mass transfer problem, we need two-way coupling, which I'm hoping to achieve with a modified version of the mapped boundary condition. I'm not sure if it's possible, but that is my goal, and seems to be the goal of the others in this thread as well. If no one else has worked on this, I guess I really need to start programming...

Best regards
Bernd

[saumavadey]

Hello!

I am stuck with a similar kind of problem.

I am developing a multi-region solver for coupling water flow over the overland surface and through stream networks using the diffusive model of Saint Venant equations. My simulation region consists of two regions: overland and channel. At the interface of the overland region, I need to exchange a flux with the channel region. The flux is one-way (overland to channel) or two-way (overland to channel and vice versa) based on a parameter Zb (bank elevation).

The flux calculations are as follows:

if (Zb > hc)
Qoc = Cd*(ho - Zb)^1.5
Qco = 0

else
Qoc = Qco = Cd*((ho - hc)^0.5)*(ho - Zb)

ho = flow depth in the overland region
hc = flow depth in the channel
Cd = a constant
Qoc = flux from overland to channel
Qco = flux from channel to overland

I seek help in how to implement it as a boundary condition on the coupled interface.

I desperately need some help as my whole work has got stuck for some time due to this.