Max Ohagen Student

Hello, I have a question about 2D axisysmmetric models for the injection and extraction of hot water into an aquifer.  The left radial axis should represent my well screen section. I already tried Well BC 4th kind for every node of the well screen and divide the desired flow rate by the total number of nodes. But I want to simulate it more realistic like a MLW in 3D. My idea was putting a Discrete Feature Element along the well screen edges and put a well BC at the top of the DFE, to simulate hot water entering the well and the aquifer from the top. However, if i put the DFE at the left most edges, the water of the Well BC does not flow along the DFE into the aquifer. I tried putting the edges and nodes of the line for the DFE 0.1m away from the left boundary (having a radius for the well of 0.1m) and then it works fine. I can imagine that this is because of the axial symmetry and that the radius and area of the DFE then would be 0, if its on the left boundary. So I'm wondering if this would be the correct way to do it in FEFLOW? Thanks, Max

Here are some screenshots for further explanation.

Hi Carlos, sorry for explaining it a bit confusing. We don’t use the plugin at the moment so its uncoupled! The problem is we have a time series for the flow rates of the BHE Array and when the flow rates drop below 20 m3/h, the Bhe error gets really high and then all temperatures are wrong. hope this helps, cheers Max

Hello everyone, I have the following problem: I created an FEFLOW Problem to model a BHE Array consisting of 64 BHEs connected in parallel, so the Input goes to all BHEs which then goes to the output. For bigger flow rates of lets say 150 m3/d the simulation runs totally fine but for flow rates below 20 m3/d the BHE Error Norm raises astronomically high causing completely wrong calculations. We coupled the BHE Array to a TRNSYS Model, with an IFM Plugin so the low flow rates somehow need to be calculated correctly. Has someone an Idea what could be the issue? We first thought laminar flow inside BHEs could be the problem, but reading the White Papers FEFLOW should handle this right? Is there any numerical parameter in the settings we are missing? I can provide the information for our chosen settings if needed! Thanks, Max