CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Community Contributions

[swak4Foam] evaporation / vapor flux / groovyBC

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 4, 2011, 23:17
Smile evaporation / vapor flux / groovyBC
  #1
New Member
 
shinya ogata
Join Date: Sep 2010
Posts: 8
Rep Power: 15
oga_shin is on a distinguished road
Hi!

I want to calculate water evaporation with simpleFoam.
I have already added moisture field as X in simpleFoam solver.
And then, I am trying to make evaporation boundary using groovyBC.

I wrote a boundary condition of vapor flux referring to heat flux.

z_
{
type groovyBC;
value uniform 0;
gradientExpression "gradX";
fractionExpression "0";
variables
"alphac=5.8+3.9*mag(internalField(U));Xs=0.0167;al fadash=3.6*alphac/3600;capadash=1;rhodash=1.2;gradX=alfadash*(Xs-internalField(X))/(kappaEffX*capadash*rhodash);";

}

SimpleFoam has done without any error.
But amount of water evaporation is too little comparing to a experiment data.

Is the boundary condition which I wrote right ?

Shinya
oga_shin is offline   Reply With Quote

Old   December 5, 2011, 05:57
Default
  #2
Assistant Moderator
 
Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,225
Rep Power: 51
gschaider will become famous soon enoughgschaider will become famous soon enough
Quote:
Originally Posted by oga_shin View Post
Hi!

I want to calculate water evaporation with simpleFoam.
I have already added moisture field as X in simpleFoam solver.
And then, I am trying to make evaporation boundary using groovyBC.

I wrote a boundary condition of vapor flux referring to heat flux.

z_
{
type groovyBC;
value uniform 0;
gradientExpression "gradX";
fractionExpression "0";
variables
"alphac=5.8+3.9*mag(internalField(U));Xs=0.0167;al fadash=3.6*alphac/3600;capadash=1;rhodash=1.2;gradX=alfadash*(Xs-internalField(X))/(kappaEffX*capadash*rhodash);";

}

SimpleFoam has done without any error.
But amount of water evaporation is too little comparing to a experiment data.

Is the boundary condition which I wrote right ?

Shinya
Don't know. Just two remarks:

a) never trust experimental data
b) if you use internalField like that I'd expect some kind of grid dependence. Try changing the resolution and see if that makes a difference
gschaider is offline   Reply With Quote

Old   December 11, 2011, 01:53
Default
  #3
New Member
 
shinya ogata
Join Date: Sep 2010
Posts: 8
Rep Power: 15
oga_shin is on a distinguished road
Hi gschaider !

Thank you for your advise!
I subdivided mesh and the amount of evaporation changed.
As you pointed, it could be mesh dependence.
I will try to find appropriate mesh.
Thank you again.

Shinya
oga_shin is offline   Reply With Quote

Old   December 11, 2011, 07:14
Default
  #4
Assistant Moderator
 
Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,225
Rep Power: 51
gschaider will become famous soon enoughgschaider will become famous soon enough
Quote:
Originally Posted by oga_shin View Post
Hi gschaider !

Thank you for your advise!
I subdivided mesh and the amount of evaporation changed.
As you pointed, it could be mesh dependence.
I will try to find appropriate mesh.
Thank you again.

Shinya
Don't adapt the mesh to fit your results. Try to find a mesh-independent formulation. Something that might help you are these functions:
http://openfoamwiki.net/index.php/Co...g_to_need_are:

Good luck
gschaider is offline   Reply With Quote

Old   December 13, 2011, 04:43
Default
  #5
New Member
 
shinya ogata
Join Date: Sep 2010
Posts: 8
Rep Power: 15
oga_shin is on a distinguished road
Hi gschaider !

Your advise is right.
Even if I found appropriate mesh comparing with experiment,
I cannot use it with another model.
I will try to make mesh-independent formulation.

Thank you again.
Shinya
oga_shin is offline   Reply With Quote

Reply

Tags
evaporation groovybc

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
Water Surface Evaporation sunggun1212 FLUENT 3 January 11, 2020 05:12
[swak4Foam] groovyBC for oscillatory flow liybzd OpenFOAM Community Contributions 5 November 12, 2018 08:53
[swak4Foam] reactingMultiPhaseEulerFoam problems with groovyBC zanilu70 OpenFOAM Community Contributions 4 December 13, 2016 07:46
[swak4Foam] Change in alpha and U with groovyBC in twoPhaseEulerFoam dani2702 OpenFOAM Community Contributions 0 November 17, 2016 04:30
Liquid Evaporation Model Error in OF 2.3.0 brbbhatti OpenFOAM 11 June 16, 2014 10:40


All times are GMT -4. The time now is 11:19.