• Re: invert flow in BHE-array

Thanks Peter. It can be implemented by means of an IFM module. We did this in an case study of a BTES (Brædstrup, Denmark). It works quite well when comparing simulated temperatures to actual measurements inside the BTES.
• Re: invert flow in BHE-array

Bump. Did you find a solution Zeno?
• BHE: Internal borehole thermal resistance

Dear FEFLOW developers,

I did a literature search on the socalled Internal Borehole Resistance that must be specified along with the Borehole Thermal Resistance if one wants to specify the latter - but I came up empty-handed. On page 854 of the FEFLOW book, there seems to be some sort of definition. There are also papers outlining a multipole method for determing resistances in a borehole but it is not easy to get something of practical use from these papers.

So to put it shortly:

Is there a closed-form expression for calculating the Internal Borehole Resistance or at least a good approximation? I mean the sensible argument in the associated white paper is that the Borehole Thermal Resistance can be specified directly - which is great if one has done a thermal response test. But the thermal response test does not give you the Internal Borehole Resistance. It would be nice if the manual elaborated a bit further on this rather complicated topic.

Søren
• Re: Modifying elements between certain nodes

Calculate the centroids (http://en.wikipedia.org/wiki/Centroid) of all elements and store them in an array.

Use one of the methods suggested in the thread below to find out which of the centroids (which comes in x and y coordinates in 2D) that are within the triangle that you define.

http://stackoverflow.com/questions/2049582/how-to-determine-a-point-in-a-triangle

Use IfmGetNode to obtain vertices (nodes) of elements.

Hope this is what you were looking for!

Best regards,
Søren

• Re: Typical values for storage compressibility [1/m]

Hi EHM,

http://www.aqtesolv.com/aquifer-tests/aquifer_properties.htm

The link contains the documentation for AQTESOLVE (software for pumping test analysis). It lists values of specific storage and also compressibility values for different types of sediments and rocks. References are provided as well. I hope it is what you are looking for :)

Best regards,
Søren
• Understanding SAMG error messages

Dear supporters,

I noticed during different transient simulations the following error message produced by the SAMG solver: "Time step #<timestep>: SAMG has NOT converged after <some integer> iterations with the residual <some number greater than 1E-8>".

It is the <some integer> that I fail to understand. Sometimes it's 5 and other times it's 7, 13 or some other integer. Solvers have an error criterion and a number of iterations to reduce the error below this criterion. The information that the solver has not reached the error criterion after say 5 iterations is pretty useless if it has another 25 iterations to further reduce the error. It would make sense if the error message was something like this: "Time step #<timestep>: SAMG has NOT converged after the maximum number of iterations with the residual <some number greater than 1E-8>"

How am I supposed to interpret this error message?

Best regards and thanks in advance!
Søren
• Re: Microsoft Visual C++ Express 2012 support

Hi Laurin,

Partly yes. Would it work with the express version aswell (which is preferable since it's free)?

And thanks a bunch for your help :)

Best regards,
Søren
• Microsoft Visual C++ Express 2012 support

I have run into this compiler problem following a reinstall of FEFLOW on a brand new PC:
https://connect.microsoft.com/VisualStudio/feedback/details/660584/windows-update-kb2455033-breaks-build-with-missing-ammintrin-h

I've given up on resolving this issue since Microsoft basically states that they won't fix this bug (which only occurs in the Express version of Visual Studio 2010 due to the lack of a x64 compiler which must be added by installing the SDK 7.1).

Will FEFLOW support plug-in development in Visual C++ Express 2012 in the foreseeable future (or does it already)?

Best regards,
Søren

• Bulk thermal conductivity

Hi WASY,

The bulk thermal conductivity in FEFLOW is, to my knowledge, calculated as the porosity-weighted average of the fluid and solid conductivities. However, in some cases the geometric mean is preferable (for example for thermal conduction in limestones in Denmark). Will you include such an option at some point or perhaps give control over this in the API?

Best regards,
Søren
• The temperature dependence of thermal conductivity

Hi WASY,

I read this post on the topic:

[url=http://www.feflow.info/forum/index.php?topic=409.0]http://www.feflow.info/forum/index.php?topic=409.0[/url]

The author of the post asks the same question but it appears that Peter Schätzl refers to hydraulic conductivity in his answer (which also is consistent with the formula displayed under Reference Temperature).

Does FEFLOW (also) consider the temperature dependence of [u]thermal[/u] conductivity?

Best regards,
Søren