|
[Sponsors] |
![]() |
![]() |
#1 |
New Member
Patrick Kastner
Join Date: Apr 2016
Posts: 10
Rep Power: 9 ![]() |
Hi everyone,
I am trying to validate a passive scalar transport case. The idea is to model the emission of simplified ![]() ![]() My current issue is that I cannot correctly reproduce average ![]() A simple mass balance can be done like this: http://www.engineeringtoolbox.com/po...oms-d_692.html As test cases I tried the simpleFoam solver as well as the passiveScalarsimpleFoam by Yan Wang. In order to keep it simple, lets start with simpleFoam. --- Steps I took: 1. The domain is a cuboid with (30*10*2.5) m, which yields 750 ![]() ![]() 2. The source term is triggered by a (volumetric) source at breathing height within the room of about 40 ![]() 3. For the source term I use a field called TS with an entry in ./0/ and dimensions of ![]() The inlet concentration should be 400 ppm (vol-based). ![]() Then, the following entry in controlDict: Code:
TS { type scalarTransport; active true; resetOnStartUp false; autoSchemes false; fvOptions { TS-01 { active true; type scalarSemiImplicitSource; scalarSemiImplicitSourceCoeffs { cellSet volumeCell; selectionMode cellSet; volumeMode absolute; // absolute <quantity>; specific <quantity>/m^3 injectionRateSuSp { TS 0.000528; //kg/s/ accounts for 64 people (number of people * density(CO2) * 15 l/h CO2 /3600s) } } } } } ![]() ![]() ![]() 5. Now, I obtain the following visual result which looks reasonable to me (inlet is on the left): ![]() An evaluation with swak4Foam yields an average value of ~1000 ppm for those conditions which is acceptable. Now, if I test this setup for different occupancies, the results get significantly worse (rel. error > 10 %), as can be seen in the following plots: http://postimg.org/gallery/icavz4dy/ The only sub-case that goes along with the static calculation, coincidentally, is the 64 people emission case. On both ends of the spectrum the results deviate significantly. In my opinion, if I change the number of people, which scales the emission linearly, the relative error should not change at all. Interestingly enough, the option specific/absolute doesn't change the result to a large extent, which is not what I would expect. In fact, the absolute option yields better results. --- With that being said, I have some questions regarding my method:
Any hint is appreciated! Kind regards, Patrick Last edited by kostnermo; September 26, 2016 at 05:29. |
|
![]() |
![]() |
![]() |
![]() |
#2 |
Member
Naresh Yathuru
Join Date: Feb 2015
Posts: 66
Rep Power: 10 ![]() |
Hi patrick,
I have the same problem and same questions. were you able to find answers for your questions? |
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Patrick Kastner
Join Date: Apr 2016
Posts: 10
Rep Power: 9 ![]() |
Hi Naresh,
I did receive some remarks as PMs but none that solve the issue. How about you share your current findings and we work it out together? ![]() Best, Patrick |
|
![]() |
![]() |
![]() |
![]() |
#4 |
Senior Member
abdikerim kurbanaliev
Join Date: Jun 2010
Location: Kyrgyzstan, Osh
Posts: 116
Rep Power: 15 ![]() |
Hi,
Could some of you please share the case setup for openfoam? Best regards |
|
![]() |
![]() |
![]() |
Tags |
gas, passive scalar, scalar, scalartransport, tracer |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
problem during mpi in server: expected Scalar, found on line 0 the word 'nan' | muth | OpenFOAM Running, Solving & CFD | 3 | August 27, 2018 04:18 |
using a Fortran library of thermodynamics inside sutherland transport model | Mehdi3031 | OpenFOAM Programming & Development | 0 | April 7, 2016 09:34 |
Issue symmetryPlane 2.5d extruded airfoil simulation | 281419 | OpenFOAM Running, Solving & CFD | 5 | November 28, 2015 13:09 |
Diverging solution in transonicMRFDyMFoam | tsalter | OpenFOAM Running, Solving & CFD | 30 | July 7, 2014 06:20 |
compressible flow in turbocharger | riesotto | OpenFOAM | 50 | May 26, 2014 01:47 |