Heat radiation

General discussion about Elmer
raback
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Re: Heat radiation

Post by raback » 07 Jul 2020, 20:24

Hi

Didn't look at the case yet but did you resolve this issue:
"ViewFactors' is not recognized as an internal or external command"
This means that when the code makes a system call to compute ViewFactors it does not find it. It does not help if it is in the bin directory if the bin directly is not in the path.

-Peter

BDesco
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Re: Heat radiation

Post by BDesco » 08 Jul 2020, 08:00

Hello,
So, if I understand you correctly, I need to tell Elmer where its own binaries are?
No, I did not deduce this from your previous answer.

I've adjusted the header of the case.sif file:

Code: Select all

Header
  CHECK KEYWORDS Warn
  Mesh DB "." "."
  Include Path "C:\Program Files\Elmer 8.4-Release\bin"
  Results Directory ""
End
Same error: 'ViewFactors' is not recognized as an internal or external command, operable program or batch file.

Thank you.

kevinarden
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Re: Heat radiation

Post by kevinarden » 08 Jul 2020, 12:39

On the elmerfem.org site are many links not just the forum.
Use the documentation link to find the Elmer models manual and Elmer Solver manual these are very helpful to read
It also includes the Elmer Tutorial manuals, work through all of the tutorials, and read the sif files that are created
There is also a link to the source code, go to fem, test, there are several examples in many different areas, work through some that interest you.

In this forum ask specific questions about problems you encounter and can't resolve on your own.

Have fun and work on the answer before trying ask questions.

BDesco
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Re: Heat radiation

Post by BDesco » 08 Jul 2020, 19:22

Hi kevinarden:
Could you explain why you think I did not do that?
Except for the source code. Requiring a user to go through the source code for simple questions (see previous posts) seems to me a bit exaggerated.
Could you point to the solution(s), if it is al that well documented?

I do not understand this kind of hostility when the documentation is clearly unclear.

Because of unclear documentation the forum is the primary source. And yes I first search the forum before asking a question.

kevinarden
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Re: Heat radiation

Post by kevinarden » 08 Jul 2020, 23:02

I think that, because I do not see any evidence in your questions that you did that prerequist work on your part. The questions are more about operating systems, and proper installation then elmer coding. Elmer has significantly more documentation than any other free open source software. I see no evidence of hostility from the support side of this conversation.

BDesco
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Re: Heat radiation

Post by BDesco » 09 Jul 2020, 09:21

Hi,
My questions:
1/
I get an error (see below). I read something of the need to define the Gebhardt factors when using diffuse grey. Doens't Elmer calculate those?
No clear answer as of yet, not in this forum not in the documentation.
2/
how to know what units the entered data is in?
Answered through this forum by Peter. To my knowledge not explained in the documentation.
3/
"how to know about your idealized explanation?"
To my knowledge not explained in the documentation.
4/
"Radiation Target Body Integer"
No explanation in the documentation what the possible values are nor what they mean.
5/
Radiation String: The type of radiation model for this boundary, one of: None, Idealized, Diffuse Gray. Note that, when using the diffuse gray radiation model, the file containing the Gebhardt factors must be given in the simulation section. Is this last part needed? Or only if the factors are already available, if not they are computed by Elmer? And how would one give "the file containing the Gebhardt factors" in "the simulation section"
. No clear answer as of yet, not in this forum not in the documentation.
6/
"So, if I understand you correctly, I need to tell Elmer where its own binaries [viewfactors.exe] are?"
No clear answer as of yet, not in this forum not in the documentation.
7/
"Searching for a solution for a viewfactors problem I've found some mentions of running viewfactors from the command line.
How do I do that? What are the switches etc .. Is there any documentation about this?"

So I thought things through. I thought: "maybe I can test where the problem lies by running the different steps one by one". I did my research and yes: found some mention about running viewfactors stand alone, but I found no further explanation whatsoever in the documentation or this forum on how to do that. Tried it several ways. Finally found no other solution than to ask the question. You answered (thank you), but I have to say running an exe from the directory that holds the file is to me not standard behavior. Normally input and output files (paths) can be provided to the exe in the command line (e.g. viewfactors.exe path1 path2) and even some switches.

"The questions are more about operating systems, and proper installation" Listed above my questions.
"then elmer coding" I thought this was at least partially a user forum (with a dedicated section for coding: "software development"). https://www.csc.fi/web/elmer/user-forums point to this forum.
So yes, do expect to get user questions if you name it 'user forum' and it also clearly is.

I think you represent my questions and my effort to get things working.
I think my questions point to some weaknesses in the documentation (I've quoted sections where explanation is clearly lacking). Faced with this situation the answer seems to be: read the code. This is not the answer I was expecting on a user forum.
Yes, I find that hostile.

kevinarden
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Re: Heat radiation

Post by kevinarden » 09 Jul 2020, 12:07

Ok, enjoy your quest to learn, many before you have not had these problems. If you can't solve them there is an Elmer VM available at elmerfem.org that should work fine.

raback
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Re: Heat radiation

Post by raback » 10 Jul 2020, 02:12

Hi,

I've answered thousands of questions over time. I try to do that using just a few minutes for each question. So the answers may be seem rude but for me this is just economy of necessity. If I don't remember something I wont usually dig it up. Therefore I cannot point where something is or is not presented.

Which is more rude to answer quickly or not to answer at all?

I did check the Gebhardt factor thing here which is not correct anymore as they are fully computed internally. This has been fixed in documentation. So things gradually always improve but are still far from perfect.

-Peter

BDesco
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Re: Heat radiation

Post by BDesco » 30 Jul 2020, 17:39

Hi Peter,
I was more referring to kevinarden about the hostility.

I now installed the VirtualBox version. I seem to be one step further (viewfactors are calculated) but still don't get results (see below).
The project files are in this thread.

Do you know of a simple example file with grey radiation? Maybe I can start from something that works. I could not find it.

Thanks.

---------------------------

ELMER SOLVER (v 8.4) STARTED AT: 2020/07/30 17:14:36
ParCommInit: Initialize #PEs: 1
MAIN: OMP_NUM_THREADS not set. Using only 1 thread per task.
MAIN:
MAIN: =============================================================
MAIN: ElmerSolver finite element software, Welcome!
MAIN: This program is free software licensed under (L)GPL
MAIN: Copyright 1st April 1995 - , CSC - IT Center for Science Ltd.
MAIN: Webpage http://www.csc.fi/elmer, Email elmeradm@csc.fi
MAIN: Version: 8.4 (Rev: 68372c6a, Compiled: 2020-07-25)
MAIN: Running one task without MPI parallelization.
MAIN: Running with just one thread per task.
MAIN: HYPRE library linked in.
MAIN: MUMPS library linked in.
MAIN: Lua interpreted linked in.
MAIN: Zoltan library linked in.
MAIN: =============================================================
MAIN:
MAIN:
MAIN: -------------------------------------
MAIN: Reading Model: case.sif
LoadInputFile: Scanning input file: case.sif
LoadInputFile: Loading input file: case.sif
LoadInputFile: Number of BCs: 4
LoadInputFile: Number of Body Forces: 0
LoadInputFile: Number of Initial Conditions: 0
LoadInputFile: Number of Materials: 1
LoadInputFile: Number of Equations: 1
LoadInputFile: Number of Solvers: 1
LoadInputFile: Number of Bodies: 1
Loading user function library: [HeatSolve]...[HeatSolver_Init0]
LoadMesh: Base mesh name: ./.
LoadMesh: Elapsed REAL time: 0.0316 (s)
MAIN: -------------------------------------
AddVtuOutputSolverHack: Adding ResultOutputSolver to write VTU output in file: case
Loading user function library: [HeatSolve]...[HeatSolver_Init]
Loading user function library: [HeatSolve]...[HeatSolver_bulk]
Loading user function library: [HeatSolve]...[HeatSolver]
RadiationFactors: ----------------------------------------------------
RadiationFactors: Computing radiation factors for heat transfer
RadiationFactors: ----------------------------------------------------
RadiationFactors: Total number of Radiation Surfaces 112 out of 688
RadiationFactors: Computing factors...
RadiationFactors: View factors filling (%) 5.9885E+01
RadiationFactors: Minimum Gebhardt factors sum 5.4356E-01
RadiationFactors: Maximum Gebhardt factors sum 9.2520E-01
RadiationFactors: Maximum share of omitted factors 0.0000E+00
RadiationFactors: Gebhardt factors filling (%) 1.0000E+02
RadiationFactors: Gebhardt factors determined (s) 1.4899E-02
RadiationFactors: All done time (s) 1.4921E-02
RadiationFactors: ----------------------------------------------------
malloc(): invalid size (unsorted)

Program received signal SIGABRT: Process abort signal.

Backtrace for this error:
#0 0x7f7f154c4cd1 in ???
#1 0x7f7f154c3ea5 in ???
#2 0x7f7f152f920f in ???
#3 0x7f7f152f918b in ???
#4 0x7f7f152d8858 in ???
#5 0x7f7f153433ed in ???
#6 0x7f7f1534b47b in ???
#7 0x7f7f1534e233 in ???
#8 0x7f7f15350418 in ???
#9 0x7f7f1590e5d5 in __listmatrix_MOD_list_getmatrixentry
at /home/elmeruser/elmerfem/fem/src/ListMatrix.F90:476
#10 0x7f7f1590e7ee in __listmatrix_MOD_list_addmatrixindexes
at /home/elmeruser/elmerfem/fem/src/ListMatrix.F90:456
#11 0x7f7f1597e4f1 in __elementutils_MOD_makelistmatrix
at /home/elmeruser/elmerfem/fem/src/ElementUtils.F90:658
#12 0x7f7f159810de in __elementutils_MOD_creatematrix
at /home/elmeruser/elmerfem/fem/src/ElementUtils.F90:1646
#13 0x7f7f15a4426c in __mainutils_MOD_addequationbasics
at /home/elmeruser/elmerfem/fem/src/MainUtils.F90:1513
#14 0x7f7f15c656b2 in addsolvers
at /home/elmeruser/elmerfem/fem/src/ElmerSolver.F90:1105
#15 0x7f7f15c714e1 in elmersolver_
at /home/elmeruser/elmerfem/fem/src/ElmerSolver.F90:398
#16 0x55839b5743cd in solver
at /home/elmeruser/elmerfem/fem/src/Solver.F90:57
#17 0x55839b57413e in main
at /home/elmeruser/elmerfem/fem/src/Solver.F90:34

raback
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Re: Heat radiation

Post by raback » 31 Jul 2020, 02:49

Hi

These are the consistency tests for diffuse gray:

Code: Select all

elmeruser@ElmerCSC-VM ~/Source/elmerfem/fem/tests $ grep -i gray */*.sif | more
InductionHeating2/crucible.sif:  Radiation = Diffuse Gray
radiation2dAA/radiation.sif:  Radiation = Diffuse Gray
radiation2d/radiation.sif:   Radiation = Diffuse Gray
radiation2dsymm/radiation.sif:   Radiation = Diffuse Gray
radiation2/radiation2.sif:   Radiation = Diffuse Gray
radiation3d/radiation.sif:   Radiation = Diffuse Gray
radiation_bin/radiation.sif:   Radiation = Diffuse Gray
radiation_dg/radiation.sif:  Radiation = Diffuse Gray
radiation/radiation.sif:   Radiation = Diffuse Gray
There has been a lot of changes quite recently so you might not have all the tests. The current code is more robust also, your problem may already have been resolved.

You should probably do some "git pull" to update the source code and recompile the code with the script that comes in the virtual machine to enjoy the latest.

I'm pretty much on the same page as Kevin here. Just trying to keep emotions aside as I do this so much.

-Peter

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