HT Model requires geometry / definition BC and ST / mesh2vtu

Usability
1

Dear all,

I am new to OGS and try to model a geothermal doublet with OGS 6.5.3.
I build a simple testcase for the problem. Within this there came up a few questions.

  1. Eventhough I am working with Version 6.5.3 I get an error, which says that I need a geometry file and on the other hand I am not allowed to have more than one .vtu file to define the boundary conditions and source terms. Why is that?

Further I worked with the .gml file which was not a problem so far.
2. However, I would like to pump hot water from a line (axially_symmetric) and inject cold water at another line (axially_symmetric). Therefore I used a Dirichlet BC for the constant cold temperature at the injection line and preassure source terms to simulate the flow rate. Somehow OGS is running, though, it is not showing the expected results.
Is it even possible to do it that way?

My files are here:
https://seafile.cloud.uni-hannover.de/f/ecf547f06dc8435ea688/?dl=1

Best,
Kim

2

Hi Kim,

I think OGS is capable to simulate what you have in mind.

Question 1.

You can use multiple meshes as input or define them using .gml file like you did. You can also mix both ways… What you are missing for using multiple input mesh is the <meshes> tag in the .prj file eg.

<meshes>
        <mesh>domain.vtu</mesh>
        <mesh>part_mesh_BC1.vtu</mesh>
        <mesh>part_mesh_BC2.vtu</mesh>
        <mesh>part_mesh_ST1.vtu</mesh>
	...
</meshes>

Question 2.

This can have multiple reasons. From your file i think you want to have some flow in the middle sandstone layer from a given pressure gradient, while injecting/extracting through two wells (the line elements). I think you are missing a second pressure boundary condition for the groundwater flow as your .prj file only has one at the moment.

A second thing could be your source terms. In OGS you have to scale source terms to the length/surface of the object. See here Scaling Source Terms . I don’t know if you already did this but for the Line type you must divide the total pump rate by the real length of the line element for a uniform extraction over this line.

I hope this helps a little with your questions

Best regards

Max

3

Hey Max,
this helps a lot. Thank you so much for your explanation.

Best,
Kim

4

I got another error which makes me uncertain in case of the meshes I use.

I meshed the model with gmsh and transformed them with msh2vtu. The output I get are the domain mesh and the mesh-parts which I defined with physical groups within the .geo file.
Can I directly use this output-meshes for ogs or do I have to do somthing specific with them?

I read in another topic, that there is another way with paraview where I could extract all boundary meshes manually. This seems like an unpleasent way, though…

Exactly error massage:
error: Could not find a global index for global component 0 for the mesh ‘Testmodel_inj’, node 2, in the corresponding bulk mesh ‘Testmodel_domain’ and node 36832. This happens because the boundary mesh is larger than the definition region of the bulk component, usually because the geometry for the boundary condition is too large.

5

I found out with constructMeshesFromGeometry that the inj and pump lines which I need for the temperature BC and the pressure ST do not have any nodes or elements, eventhough I set up the searchlength to 1e-3 I get the following warning:
[warning] The created mesh ‘Testmodel_inj_sand’ hasn’t any nodes or elements and thus it isn’t written to file.

I checked the mesh closer and found out that the line was not included in the mesh. Therefore I added an embedded line in my .geo file and recreated the mesh again gmsh and transformed them with msh2vtu. The boundary meshes are worinking fine now.

I only still have trouble with the pressure source terms.