CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   OpenFOAM (https://www.cfd-online.com/Forums/openfoam/)
-   -   evaporation / vapor flux / groovyBC (https://www.cfd-online.com/Forums/openfoam/95058-evaporation-vapor-flux-groovybc.html)

 oga_shin December 4, 2011 23:17

evaporation / vapor flux / groovyBC

Hi!

I want to calculate water evaporation with simpleFoam.
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;
fractionExpression "0";
variables

}

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

 gschaider December 5, 2011 05:57

Quote:
 Originally Posted by oga_shin (Post 334617) 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

 oga_shin December 11, 2011 01:53

Hi gschaider !

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

 gschaider December 11, 2011 07:14

Quote:
 Originally Posted by oga_shin (Post 335421) 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
http://openfoamwiki.net/index.php/Co...g_to_need_are:

Good luck

 oga_shin December 13, 2011 04:43

Hi gschaider !