cassius

I am modelling a Borehole Heat Exchanger field with 168 exchangers, all of them with the same features, the same thermal load and the same depths.
I would like to know if it is possibile to insert them in the mesh with a special procedure (e.g. using a .trp file with assign_>database, or something similar), or if I have to put them one by one.

Thanks,
Alessandro

which timestep scheme you adopted?
I experienced some troubles with the Adams-Bashfort scheme, you could try with Forward Euler/Backward Euler...

I am carrying out a sensitivity analysis on which settings work better with a flow and heat transport modeling of a Borehole Heat Exchanger, vaying:
- automatic timestep control (FE/BE, Adams-Bashforth, fully implicit and semi-implicit);
- error tolerance (10, 5, 1 x 10^-3) applied to RMS norm;
- upwinding scheme.

Which is your advice for BHE modeling?

Kind regards,
Alessandro Casasso

I found that the IFM module "lambdat.dll" is able at varying the thermal conductivity according to the node temperature, using the Zoth and Hänel (1988) formula...

I was looking on the white papers and I saw that constitutive laws can be implemented in FEFLOW for viscosity, density etc. and also for parameters like heat conductivity.
I am very interested in this possibility, because it can be useful for modelling, i.e., groundwater filled borehole heat exchangers in which water can become ice and hence heat conductivity can be greatly enhanced (from 0.59 to 2.2 W/(mK)!!!).
Is it possibile, and if, how?
Thank you for your attention.

About PEST, I am trying to run a model with the IFM module of PEST loaded, but it doesn't work...is there any restrictions in launching models with IFM modules in batch mode?

I can explain better.
I am using a transient 3d flow model with the IFM module PEST 2.0.
I would like to run it in a batch mode for a faster run, writing a .dac file and a .log file (is it possible to write also the record file? .rec).

My batch code is:
"C:\Programmi\WASY\FEFLOW 6.0\bin32\feflow60c.exe" -module "C:\Programmi\WASY\FEFLOW 6.0\modules32\pest20.dll" -run -demo -work C:\ -steps steps.pow -dac PEST.dac 10_10_01_PEST.fem

(I own a license, but I'm working in demo mode because another PEST model is already running...).

As I try to run this .bat file, this screen appears:

[img width=200 height=160]http://areeweb.polito.it/ricerca/groundwater/troubles/batch_mode_PEST_error.png[/img]

What do these messages mean?

Thanks a lot,
Alessandro Casasso

I tried the IFM module bhe_loop we saw at the course in Offenburg, but this strange error occurs:

[img width=200 height=160]http://areeweb.polito.it/ricerca/groundwater/troubles/bhe_loop_troubles.JPG[/img]

[url=http://areeweb.polito.it/ricerca/groundwater/troubles/bhe_loop_troubles.JPG] http://areeweb.polito.it/ricerca/groundwater/troubles/bhe_loop_troubles.JPG [/url]

A message "A transient BC cannot be modified" appears.

I made the nodal reference distribution BHE-dT, putting a value of 1 in the BHE node, and -9999 elsewhere.
I put the BHE boundary condition with ID=1. As I started, this message box appeared.

Can you please help me? Thank you.

Kind regards,
Alessandro Casasso

Dear Wolfram,
thank you for your help!

Here you can see an example:
[img width=200 height=160]http://areeweb.polito.it/ricerca/groundwater/troubles/slight_differences.GIF[/img]

[url=http://areeweb.polito.it/ricerca/groundwater/troubles/slight_differences.GIF] http://areeweb.polito.it/ricerca/groundwater/troubles/slight_differences.GIF [/url]

I am simulating a 100m deep 2U borehole heat exchanger.
The reference temperature is 10°C, and the prescribed inlet temperature is of about 14.7 °C.
For every other parameter, I kept the default value.
No hydraulic gradient is present, as I put a uniform fixed hydraulic head value on the boundary.
The aquifer is unconfined with "phreatic" option.

A slight difference of about 0.3 °C occurs.

This bug occurs only with Feflow 5.4; in the 6.0 version (with the "old fashion" Motif GUI), everything is ok with outlet temperatures...

Kind regards,
Alessandro

It's the 5.4.5412-x86 version, I think it's the most recent one.

I am trying to run Feflow 5.3 / 5.4 demo on a server with Windows 2003 32 bit.
I installed Feflow 5.3, Exceed 2006 (x86) and Netlm4.3.4 and everything was ok, but as I tried to run Feflow I found this message boxes:

[img width=200 height=150]http://areeweb.polito.it/ricerca/groundwater/troubles/PROBLEM%20FEFLOW%205.3.JPG[/img]

see the full size image here:
http://areeweb.polito.it/ricerca/groundwater/troubles/PROBLEM%20FEFLOW%205.3.JPG

What's the matter?