CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

buoyantPimpleFoam with humidity

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By nullicle

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 16, 2020, 23:47
Default buoyantPimpleFoam with humidity
  #1
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Hi all,

I am currently modelling heat transfer in a house with buoyantPimpleFoam and I am wanting to take variable humidity into account. I cannot seem to find any tutorials or information about other solvers that do this.

Thus, does anyone know of whether a solver like this is available?

Thanks in advance,

Chris
nullicle is offline   Reply With Quote

Old   September 17, 2020, 06:09
Default
  #2
Senior Member
 
Domenico Lahaye
Join Date: Dec 2013
Posts: 517
Blog Entries: 1
Rep Power: 14
dlahaye is on a distinguished road
Allow radiative heat transfer with absorption coefficient that depends on H2O mass fraction? If yes, see reserveBurner tutorial of bouyantSimpleFoam. Possibly (?) is suffices to with reactions and combustion off.
dlahaye is offline   Reply With Quote

Old   September 17, 2020, 20:15
Default
  #3
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Quote:
Originally Posted by dlahaye View Post
Allow radiative heat transfer with absorption coefficient that depends on H2O mass fraction? If yes, see reserveBurner tutorial of bouyantSimpleFoam. Possibly (?) is suffices to with reactions and combustion off.
Thanks, I found it in the chtMultiRegionFoam and had a glance through the source code (could not find any written explanation as to what this case actually is...)

So it seems I should not find a different solver, rather add the appropriate functionality that replicates the chemical process, namely the interaction with air/water? Is there anywhere that actually explains this tutorial with words, so I can match it to the code? Or interaction with air/water for humidity elsewhere?

Thanks,

Chris
nullicle is offline   Reply With Quote

Old   September 18, 2020, 03:17
Default
  #4
Senior Member
 
Domenico Lahaye
Join Date: Dec 2013
Posts: 517
Blog Entries: 1
Rep Power: 14
dlahaye is on a distinguished road
No clue on water/air interactions.

Chemical reactions can be added as shown in the reverseBurner tutorial and in the tutorials on the combustion solver (reactingFoam and related).

Apologies for being vague.
dlahaye is offline   Reply With Quote

Old   September 18, 2020, 04:28
Default
  #5
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Quote:
Originally Posted by dlahaye View Post
No clue on water/air interactions.

Chemical reactions can be added as shown in the reverseBurner tutorial and in the tutorials on the combustion solver (reactingFoam and related).

Apologies for being vague.
Thanks this is helpful. I think for now the way forward is to study these tutorials to find the right way to add the reaction in. If I have issues I will reply again to this thread.

Thanks!
dlahaye likes this.
nullicle is offline   Reply With Quote

Old   October 8, 2020, 04:58
Default Back to it
  #6
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Hi again,

I have successfully updated my thermophysicalProperties file to include a mixture of air and water. The important part is:

thermoType
{
type heRhoThermo;
mixture reactingMixture;
transport sutherland;
thermo janaf;
equationOfState perfectGas;
specie specie;
energy sensibleEnthalpy;
}

inertSpecie air;

chemistryReader foamChemistryReader;

foamChemistryFile "<constant>/foam.inp";

foamChemistryThermoFile "<constant>/foam.dat";

where the species are set in foam.inp:

H2O
{
specie
{
molWeight 18.0153;
}
thermodynamics
{
Tlow 200;
Thigh 3500;
Tcommon 1000;
highCpCoeffs ( 3.03399 0.00217692 -1.64073e-07 -9.7042e-11 1.68201e-14 -30004.3 4.96677 );
lowCpCoeffs ( 4.19864 -0.00203643 6.5204e-06 -5.48797e-09 1.77198e-12 -30293.7 -0.849032 );
}
transport
{
As 1.67212e-06;
Ts 170.672;
}
}

air
{
specie
{
molWeight 28.9596;
}
thermodynamics
{
Tlow 200;
Thigh 3500;
Tcommon 1000;
highCpCoeffs ( 3.57304 -7.24383e-04 1.67022e-06 -1.26501e-10 -4.20580e-13 -1047.41 3.12431 );
lowCpCoeffs ( 3.09589 1.22835e-03 -4.14267e-07 6.56910e-11 -3.87021e-15 -983.191 5.34161 );
}
transport
{
As 1.67212e-06;
Ts 170.672;
}
}

I have combustion, radiation and reactions off and added appropriate air and H2O files in the 0 directory. This runs no problem.

The problem is now I need to compute individual properties of the gases using the ideal gas law in order to calculate the relative humidity. Is there a relevant tutorial somewhere that computes properties of the individual gases?

I also noticed that unlike the reverseBurner tutorial for example, the air and H2O files in subsequent times are not updated. I assume this is because their mass fractions remain equal? I am not pumping anything in or taking anything out.

Thanks in advance.
nullicle is offline   Reply With Quote

Old   October 8, 2020, 18:48
Default
  #7
Senior Member
 
Joachim Herb
Join Date: Sep 2010
Posts: 648
Rep Power: 20
jherb is on a distinguished road
As far as I know, buoyantPimpleFoam cannot be used to simulate different species. It just ignores the air and H2O files and calculates if as there is just one species. Look at the other solvers like reactingFoam. There you see in the output, that at least one equation for the species concentration is solved.
jherb is offline   Reply With Quote

Old   October 8, 2020, 20:22
Default
  #8
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Quote:
Originally Posted by jherb View Post
As far as I know, buoyantPimpleFoam cannot be used to simulate different species. It just ignores the air and H2O files and calculates if as there is just one species. Look at the other solvers like reactingFoam. There you see in the output, that at least one equation for the species concentration is solved.
That matches what I see, in that the later files for H2O etc are exactly the same as the initial one (i.e. not filled with values).

So reactingFoam should do everything that buoyantPimpleFoam does, but with the added functionality of evolving the mixtures? I've noticed for example the reverseBurner tutorial in chtMultiRegionFoam evolves the mixtures.

Thanks.
nullicle is offline   Reply With Quote

Old   October 10, 2020, 19:17
Default
  #9
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Update:

I have the thing running with rhoReactingBuoyantFoam, however the results are not as expected.

I am modelling a room at a fixed temperature with an inlet blowing in hot air, and I am trying to incorporate water vapour.

What I find when using buoyantPimpleFoam is that the heat is not transferred through the air very fast, and it is quite localised. However when using rhoReactingBuoyantFoam (or just rhoPimpleFoam) with just air, the heat gets transferred to the entire room very quickly and it heats up uniformly, looking very unrealistic. I am guessing this has something to do with the thermophysicalProperties, although I use the same for both solvers above.

Is there anyone out there who has an idea about this?

I attach two pictures below of temperature on a vertical slice of the room after some time, one solved with buoyantPimpleFoam, the other with rhoReactingBuoyantFoam. One can see how the room is heated much quicker with the rhoReactingBuoyantFoam solver, and this has me worried. Sorry about the quality, but the point I'm trying to make is obvious nonetheless.

Thanks in advance.

Last edited by nullicle; October 10, 2020 at 21:15.
nullicle is offline   Reply With Quote

Old   October 10, 2020, 21:13
Default
  #10
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Two pictures.
Attached Files
File Type: pdf buoyantPimpleFoam_T.pdf (10.1 KB, 33 views)
File Type: pdf rhoReactingBuoyantFoam_T.pdf (16.1 KB, 31 views)
nullicle is offline   Reply With Quote

Old   October 10, 2020, 23:18
Default
  #11
New Member
 
Chris
Join Date: Sep 2020
Posts: 8
Rep Power: 4
nullicle is on a distinguished road
Update #2:

I think the reason why the temperature increases everywhere is because the pressure increases rapidly everywhere after not so many iterations. This could be because I have no outlet, but I have the BC of the inlet for the air file as

Heatpump_Inlet
{
type fixedValue;
value uniform 0;
}

So I am not "pumping in air", but rather blowing it around. I will run a test case with an outlet and see if that makes a difference.
nullicle is offline   Reply With Quote

Old   October 3, 2022, 06:51
Post similar case
  #12
New Member
 
Khafagy
Join Date: Jul 2022
Location: Cairo
Posts: 1
Rep Power: 0
khafagy is on a distinguished road
Hi nullicle,

I am currently doing a very similar case (blowing hot humid air into a room and observing the temperature and the relative humidity). So I were wondering did you finish your case? If so, can you help me figuring out which solver did you use in addition to the updated thermophysical properties!

Thank you in advance.
khafagy is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Which solver required for humidity and temperature distributiion Sandy7 STAR-CCM+ 2 January 25, 2017 03:17
relative humidity more than 100%!! unable to understand why this is happening amasugi14 FLUENT 1 December 1, 2015 22:01
buoyantPimpleFoam Convergence Issues joel.lehikoinen OpenFOAM 1 December 5, 2013 15:58
Condensation of water if humidity > 100% Wikie FLUENT 4 November 11, 2010 14:57
Condensation of water if humidity > 100% via UDF Wikie Fluent UDF and Scheme Programming 0 November 9, 2010 17:41


All times are GMT -4. The time now is 17:47.