CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Pre-Processing

vaporize water - boundary conditions

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 25, 2011, 11:36
Unhappy vaporize water - boundary conditions
  #1
Senior Member
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,100
Blog Entries: 6
Rep Power: 19
Tobi will become famous soon enough
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Hi together,

i am working on a testcase in which water vaporizes on a heated wire (diameter = 0,1 mm)

The case is working well but i 've problems with my BC couse my steam don't get out of my integration area. In the video i added you can see that its circulating in the case but i wanna let it out.

VIDEO : http://ww3.cad.de/foren/ubb/uploads/...eWater.mpg.zip

So my Boundary-File looks like that:

Code:

top
{
    type            patch;
    nFaces          100;
    startFace       42335;
}bottom
{
    type            patch;
    nFaces          100;
    startFace       42435;
}
right
{
    type            slip;
    nFaces          170;
    startFace       42535;
}
symmetryZY
{
    type            symmetryPlane;
    nFaces          300;
    startFace       42705;
}
heat
{
    type            wall;
    nFaces          60;
    startFace       43005;
}
empty
{
    type            empty;
    nFaces          42700;
    startFace       43065;
}

my U and p_rgh files are:

Code:
dimensions      [ 0 1 -1 0 0 ];internalField   uniform ( 0 0 0 );
boundaryField
{
    symmetryZY
    {
        type            symmetryPlane;
    }
    heat
    {
        type            fixedValue;
        value           uniform ( 0 0 0 );
    }
    empty
    {
        type            empty;
    }
    right
    {
        type            slip;
    }
    bottom
    {
        type            outletInlet;
        value           $internalField;
        outletValue     $internalField;
    }
    top
    {
        type            inletOutlet;
        inletValue      $internalField;
        value           $internalField;
    }
}


and the p_rgh file is:

Code:
dimensions      [ 1 -1 -2 0 0 ];internalField   uniform 101325;
boundaryField
{
    symmetryZY
    {
        type            symmetryPlane;
    }
    heat
    {
        type            buoyantPressure;
        value           $internalField;
    }
    empty
    {
        type            empty;
    }
    right
    {
        type            slip;
    }
    top
    {
        type            totalPressure;
        phi             phi;
        U               U;
        gamma           1;
        rho             rho;
        psi             none;
        p0              $internalField;
        value           $internalField;
    }
    bottom
    {
        type            buoyantPressure;
        value           $internalField;
    }
}



Any tricks or suggestions?
Thx in advance,
Tobi

Tobi is offline   Reply With Quote

Old   November 26, 2011, 23:35
Default
  #2
Senior Member
 
Nima Sam
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,124
Blog Entries: 1
Rep Power: 14
nimasam is on a distinguished road
Send a message via Yahoo to nimasam
hi
first of All, what is your solver?
second i may try inletOutlet or zeroGradient for bottom in U
nimasam is offline   Reply With Quote

Old   November 27, 2011, 07:01
Default
  #3
Senior Member
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,100
Blog Entries: 6
Rep Power: 19
Tobi will become famous soon enough
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Quote:
Originally Posted by nimasam View Post
hi
first of All, what is your solver?
second i may try inletOutlet or zeroGradient for bottom in U

Hey nimasam,

my Solver is interPhaseChangeFoam with implement temperatur field and temperatur depended pSat.


Okay i ll try inletOutlet/zeroGradient for the bottom.
I 've tryed to use pressureInletOutletVelocity for the top BC like in the tutorial "breakdam" but the steam can not get out.

okay i ll change the bottom BC and ll tell you if its working.

Thx for replaying
Tobi
Tobi is offline   Reply With Quote

Old   November 28, 2011, 06:02
Default
  #4
Senior Member
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,100
Blog Entries: 6
Rep Power: 19
Tobi will become famous soon enough
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Hi,

i 've solved the case with your advice to change the bottom to zeroGradient or inletOutlet (refer to U).

The steam doesn#t get out of the boundarys
Tobi is offline   Reply With Quote

Old   December 3, 2011, 06:56
Default
  #5
egp
Senior Member
 
egp's Avatar
 
Eric Paterson
Join Date: Mar 2009
Location: Blacksburg, VA
Posts: 197
Blog Entries: 1
Rep Power: 9
egp is on a distinguished road
Hi Tobi,

Do you have a reference for the temperature dependent Psat model that you are using?

Thanks, Eric
egp is offline   Reply With Quote

Old   December 3, 2011, 09:09
Default
  #6
Senior Member
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,100
Blog Entries: 6
Rep Power: 19
Tobi will become famous soon enough
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Quote:
Originally Posted by egp View Post
Hi Tobi,

Do you have a reference for the temperature dependent Psat model that you are using?

Thanks, Eric

Hi Eric, yes i have the temperature dependent Psat correlation from August-Roche-Magnus.

My simulation is working now and the solution seeems very good.
But i am waiting for experimental values.

I am still trying to get a good solution and handle the BC for that case.
Hope i could help you.

Tobi
Tobi is offline   Reply With Quote

Old   December 3, 2011, 09:14
Default
  #7
egp
Senior Member
 
egp's Avatar
 
Eric Paterson
Join Date: Mar 2009
Location: Blacksburg, VA
Posts: 197
Blog Entries: 1
Rep Power: 9
egp is on a distinguished road
Hi Tobi,

Thanks. Can you give me a citation for August-Roche-Magnus?

There is a student in our group who is looking at laser-induced vaporization for creating a bubble. Very high-temperature, short duration pulse of energy. She has the heat-transfer and energy absorption modeled, and is now working on the vaporization.

Eric

Quote:
Originally Posted by Tobi View Post
Hi Eric, yes i have the temperature dependent Psat correlation from August-Roche-Magnus.

My simulation is working now and the solution seeems very good.
But i am waiting for experimental values.

I am still trying to get a good solution and handle the BC for that case.
Hope i could help you.

Tobi
egp is offline   Reply With Quote

Old   December 3, 2011, 09:40
Default
  #8
Senior Member
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,100
Blog Entries: 6
Rep Power: 19
Tobi will become famous soon enough
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Quote:
Originally Posted by egp View Post
Hi Tobi,

Thanks. Can you give me a citation for August-Roche-Magnus?

There is a student in our group who is looking at laser-induced vaporization for creating a bubble. Very high-temperature, short duration pulse of energy. She has the heat-transfer and energy absorption modeled, and is now working on the vaporization.

Eric

Hi Eric,

i used the equation from http://www.tfd.chalmers.se
I ve no citation for that - exept google and wiki

and you can implement it with that code:

Code:
{
const dimensionedScalar t30_11("30.11", dimensionSet(0,0,0,1,0,0,0), 30.11);
const dimensionedScalar t273_15("273.15", dimensionSet(0,0,0,1,0,0,0), 273.15);
const dimensionedScalar t1("1", dimensionSet(0,0,0,1,0,0,0), 1);
const dimensionedScalar p610_94("610.94", dimensionSet(1,-1,-2,0,0,0,0), 610.94);
// dimensionSet( [kg], [m], [s], [K], [kg*mol], [A], [cd]), [kg/(m*S^2)]=[Pa]
// August-Roche-Magnus formula
pSat = p610_94 * exp( 17.625*(T-t273_15) / max(t1, T-t30_11) );
//max(1,...) is included to avoid problems with devision by 0
}
Tobi


PS: I am interested to get the bubbles involved in my solver couse i wanna simulate the heat transfer from a heated wire.

Like -
free convection
bubble convection
and film convection

i am not sure if thats correct translated but in my case i don 't get bubbles.
Tobi is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Water subcooled boiling Attesz CFX 7 January 5, 2013 04:32
Impinging Jet Boundary Conditions Anindya Main CFD Forum 24 January 11, 2012 14:40
mesh file for flow over a circular cylinder Ardalan Main CFD Forum 6 April 17, 2010 23:40
mass flow in is not equal to mass flow out saii CFX 2 September 18, 2009 08:07
Solver error message!!! IoSa CFX 1 September 14, 2006 04:48


All times are GMT -4. The time now is 17:59.