Solving 1D-equation on each patch face

chriss85 · October 20, 2014, 06:45

I would like to solve a one-dimensional transient heat conduction equation on each patch face of a boundary.
What kind of approach is best suited for this?
1) Extruding each patch face in a new mesh on which the equation is solved, using empty boundaries at the sides?
2) Manually discretizing the equation and write my own solver algorithm?
3) I think I also read in one of the later release notes about ODE-solving capabilities, but I haven't investigated this yet (will do once I find some time).

Does anyone know of a similar use case with a reference implementation that I could use as a template?

chriss85 · October 23, 2014, 09:25

I made some progress on this and wanted to share it.

OpenFOAM already contains a very nice tool for creating 1d-extruded meshes from a boundary, called extrudeToRegionMesh. Using this, it is possible to create separate meshes with 1d-extrusions which can be coupled to the primary mesh (see chtMultiRegionFoam as an example).

I haven't done the programming yet, but I'm very confident this will work just like I need it.

giack · October 13, 2016, 03:51

Hi Crhiss,

let's see if I understood it properly: with extrudeToRegionMesh it is possible to create a mesh from a boundary, map the variables in the new mesh and run on that a 1D solver. Am I right?

I'm trying to figure out how to solve an implicit equation on a boundary and this method could help.

Regards

chriss85 · October 13, 2016, 04:34

It creades a new region containing extruded cells where you can choose if they are 1D for each boundary face or connected to each other IIRC. You can then use this mesh and solve equations on it. It's also possible to couple it using the appropriate boundary conditions. Keep in mind that the coupling is done in a segregrated approach, meaning you need to solve the equations on the meshes separately, possibly in a loop.

Zeppo · October 14, 2016, 11:26

Quote:

Originally Posted by chriss85

Keep in mind that the coupling is done in a segregrated approach, meaning you need to solve the equations on the meshes separately, possibly in a loop.

Do you know how can I transform them into a coupled system?

Elliptic CFD · October 14, 2016, 15:44

Quote:

Originally Posted by chriss85

I made some progress on this and wanted to share it.

OpenFOAM already contains a very nice tool for creating 1d-extruded meshes from a boundary, called extrudeToRegionMesh. Using this, it is possible to create separate meshes with 1d-extrusions which can be coupled to the primary mesh (see chtMultiRegionFoam as an example).

I haven't done the programming yet, but I'm very confident this will work just like I need it.

Please, could you give the steps on how this is done. For my project, I want to extrude a mesh from the wall boundary into the fluid region. Hence, a 1D code will be used for the embedded mesh to calculate wall shear stress fields that will feed into the main mesh.

If I can get the extrudeToRegionMesh utility to work properly, I could use it to create embedded meshes for more complex geometries than channel flow

chriss85 · October 17, 2016, 05:05

Check the example dictionary in the tools directory (applications/utilities/mesh/generation/extrude/extrudeToRegionMesh) for the possible options you can use with this tool. In the end it will generate a new mesh as a separate region, so your solver will need to be able to work with multiple regions in a case. You will probably also need some kind of mapped boundary condition. On the extruded case you can solve equations in the same way as you would on a single mesh.

October 20, 2014, 06:45	Solving 1D-equation on each patch face	#1
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	I would like to solve a one-dimensional transient heat conduction equation on each patch face of a boundary. What kind of approach is best suited for this? 1) Extruding each patch face in a new mesh on which the equation is solved, using empty boundaries at the sides? 2) Manually discretizing the equation and write my own solver algorithm? 3) I think I also read in one of the later release notes about ODE-solving capabilities, but I haven't investigated this yet (will do once I find some time). Does anyone know of a similar use case with a reference implementation that I could use as a template?

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October 23, 2014, 09:25		#2
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	I made some progress on this and wanted to share it. OpenFOAM already contains a very nice tool for creating 1d-extruded meshes from a boundary, called extrudeToRegionMesh. Using this, it is possible to create separate meshes with 1d-extrusions which can be coupled to the primary mesh (see chtMultiRegionFoam as an example). I haven't done the programming yet, but I'm very confident this will work just like I need it.

October 13, 2016, 03:51		#3
giack Member Join Date: Mar 2013 Posts: 98 Rep Power: 13	Hi Crhiss, let's see if I understood it properly: with extrudeToRegionMesh it is possible to create a mesh from a boundary, map the variables in the new mesh and run on that a 1D solver. Am I right? I'm trying to figure out how to solve an implicit equation on a boundary and this method could help. Regards

October 13, 2016, 04:34		#4
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	It creades a new region containing extruded cells where you can choose if they are 1D for each boundary face or connected to each other IIRC. You can then use this mesh and solve equations on it. It's also possible to couple it using the appropriate boundary conditions. Keep in mind that the coupling is done in a segregrated approach, meaning you need to solve the equations on the meshes separately, possibly in a loop.

October 17, 2016, 05:05		#7
chriss85 Senior Member Join Date: Oct 2013 Posts: 397 Rep Power: 18	Check the example dictionary in the tools directory (applications/utilities/mesh/generation/extrude/extrudeToRegionMesh) for the possible options you can use with this tool. In the end it will generate a new mesh as a separate region, so your solver will need to be able to work with multiple regions in a case. You will probably also need some kind of mapped boundary condition. On the extruded case you can solve equations in the same way as you would on a single mesh.