Initial conditions in BHE simulation

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1

Hi everyone,

I am using OGS for BHE simulation. I have two questions.

  1. I did a TH simulation and got the temperature and pressure in the mesh, and I want to use it as an initial condition for soil temperature. The problem is that once I define BHE as a physical curve, the temperature would take the Dirichlet BC of the surface all the way (10 degrees). I cannot also remove it as a physical entity in my mesh since I need it later for the BHE simulation. How can I rectify this problem?

  2. How can I get the outlet temperature of the BHE?

Best regards,
Farid

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2

Dear Farid,

thanks for your questions.

  1. The initial condition can be set in the prj-file in the process variables section for every process variable. You need to define a parameter, which can be used to set the initial condition. There are various options, in your case the MeshNode type should be the right one.
<parameter>
     <name>T0_Soil</name>
     <type>MeshNode</type>
     <mesh>SOIL_Initial</mesh>
     <field_name>temperature_soil</field_name>
</parameter>

If you want to set a Dirichlet BC at the top surface of the model, the BHE should not start at a node in the top surface. Let the BHE begin in a depth of -1m or so and everything runs well.

  1. At every BHE-Node you will get a vector of the BHE-Temperatures. For 1U there are 4 Temperatures: {BHE_inflow, BHE_outflow, BHE_grout_1, BHE_grout_2}.
    For 2U there 8 temperatures: {BHE_inflow_1, BHE_inflow_2, BHE_outflow_1, BHE_outflow_2, BHE_grout_1, BHE_grout_2, BHE_grout_3, BHE_grout_4}.

Best regards,
Max

1 Like
3

Dear Max,

Thank you very much for your response. I got it working during the holidays. But I encountered another problem. I wanted to make density of the fluid in the formation as a function of temperature but I got the error that “temperature_soil” is not a defined variable while it is definitely defined as a process variable. Do you know how that can be solved?

Best regards,
Farid

4

Dear Farid,

do you want to make the density of AqueousLiquid in a defined media temperature dependent? Then you must name it temperature and it works - the reason for this, is also not clear for me. If you want to modeling the refrigerant density as a temperature dependent function, it is from my knowledge not yet possible.

Best regards,
Max

1 Like
5

Dear Max,

Yes, It is precisely as you said. I will try it then. I appreciate your help and support.

Best regards,
Farid Arabameri