Pablo Friedolin Leon Hübner Student

I am modelling a thermal response test. I have a unsaturated model without any flow, I have checked the darcy flux (nodal) and it is maximum e-22 m/d in the soil/ground. I have parametrized the area around my Borehole Heat Exchanger (BHE) with the parameter lookup table. My solid thermal conductivity is significantly larger than my fluid thermal conductivity (2 orders of magnitude). 

I am having the following issue: I am doing a manual sensitivity analysis so I changed the parameter of porosity (heat). Per my understanding of heat transfer in unsaturated conditions, I would expect the effective thermal conductivity to increase with decreasing porosity (due to the greater Thermal Conductivity (TC) of the solid compared to the fluid). Nevertheless the opposite seems to be happening. I am basing the changes of the effective TC off of local temperature charts with observation points at certain distances to the BHE. 

I am assuming this has to do with the fact that the porosity property increases the effective porosity available for heat transfer; what I don´t understand how that is significant considering I do not have flow, and my fluid has a very low thermal conductivity. If I calculate the effective thermal conductivity manually it decreases with increasing porosity. I am wondering if there is anything I am not taking into consideration that could be leading to this or whether it is an issue with the code.

Short Version: By my understanding, the only way to have FEFLOW calculate the bulk/effective thermal conductivity of materials is by providing the property: Porosity (heat), nevertheless changing this parameter is leading to unexpected results. 

Any assistance would be much appreciated. Thank you in advanced!
 

I have found the settings under the Equation of State tab. Maybe the Documentation could be updated to say as much.

I was using FEFLOW 8.1 until very recently, and I was setting up a custom viscosity and temperature for my fluid. I did this in the Transport Settings --> Reference Parameters. The option to set this seems to have disappeared in FEFLOW 10.0, is this correct? When checking the Documentation for FEFLOW 10.0 it mentions that the reference viscosity is located under the transport settings but I haven't been able to find it. 

Thank you Björn,  for anyone else coming across this thread: My version of the FEFLOW Book, had the section on fully discretized BHE in 3D, in Chapter 13.6.4.