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

Boundary conditions MultiRegionHeater

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 25, 2013, 07:10
Post Boundary conditions MultiRegionHeater
  #1
New Member
 
Bárbara Arizmendi
Join Date: Oct 2013
Location: Spain
Posts: 6
Rep Power: 2
Barbara is on a distinguished road
Hi Foamers!
I'm new to OpenFoam and I'm working with multiRegionFoam. I've played correctly the tutorial multiRegionHeater but now I'm doing some changes. I'd like to set the T value of the heater to 500 K and delete the condition of the minY which is a fixed temperature. In the changeDictionarydict I've the folllowing script:


Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
   version     2.0;
   format      ascii;
   class       dictionary;
   object      changeDictionaryDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
dictionaryReplacement
{
   boundary
   {
       minY
       {
           type            wall;
       }
 
   }
 
   T
   {
       internalField   uniform 300;
 
       boundaryField
       {
           ".*"
           {
               type            zeroGradient;
               value           uniform 300;
           }
           "heater_to_.*"
           {
 
               type            compressible::turbulentTemperatureCoupledBaffleMixed;
               neighbourFieldName T;
               kappa           solidThermo;
               kappaName       none;
               value           uniform 500;
           }
           minY
           {
               type            zeroGradient;
value           uniform 300;
           }
       }
   }
}
 
// ************************************************************************* //
I've run the case and It doesn't converge. I've waited for 2 hour and I don't get any solution. Is it a problem of the code or do I have to wait longer time?

Thanks you
Barbara is offline   Reply With Quote

Old   October 25, 2013, 12:21
Smile
  #2
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
welcome barbara,

Quote:
Originally Posted by Barbara View Post
Hi Foamers!
I'm new to OpenFoam and I'm working with multiRegionFoam. I've played correctly the tutorial multiRegionHeater but now I'm doing some changes. I'd like to set the T value of the heater to 500 K and delete the condition of the minY which is a fixed temperature. In the changeDictionarydict I've the folllowing script:


Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
   version     2.0;
   format      ascii;
   class       dictionary;
   object      changeDictionaryDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
dictionaryReplacement
{
   boundary
   {
       minY
       {
           type            wall;
       }
 
   }
 
   T
   {
       internalField   uniform 300;
 
       boundaryField
       {
           ".*"
           {
               type            zeroGradient;
               value           uniform 300;
           }
           "heater_to_.*"
           {
 
               type            compressible::turbulentTemperatureCoupledBaffleMixed;
               neighbourFieldName T;
               kappa           solidThermo;
               kappaName       none;
               value           uniform 500;
           }
           minY
           {
               type            zeroGradient;
value           uniform 300;
           }
       }
   }
}
 
// ************************************************************************* //
I've run the case and It doesn't converge. I've waited for 2 hour and I don't get any solution. Is it a problem of the code or do I have to wait longer time?

Thanks you


actually you didn't delete the condition of minY, i can see it in your file.another thing don't only delete it from your file because ".*" means put this condition for every patch which haven’t another declared BC. so, you must delete ".*" also and put your conditions for all your patches yourself. but notice that if this patch still in your mesh you must put condition for it otherwise OpenFOAM won't run.

Code:
   minY
           {
               type            zeroGradient;
                 value           uniform 300;
           }
i can see that you put value for zeroGradient BC and this is wrong you must
change zeroGradient to fixedValue or delete value entry.

i hope this help you.
Ahmed Khattab is offline   Reply With Quote

Old   October 28, 2013, 05:19
Default
  #3
New Member
 
Bárbara Arizmendi
Join Date: Oct 2013
Location: Spain
Posts: 6
Rep Power: 2
Barbara is on a distinguished road
Thanks for your answer. I've tried to do what you have told me but it doesn't converge. I've a question, Is the way to fix the temperature correct? Because in the tutorial, the temperature of the heater is variable and I want to fix it.

Thanks you
Barbara is offline   Reply With Quote

Old   October 28, 2013, 15:11
Default
  #4
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
Quote:
Originally Posted by Barbara View Post
Thanks for your answer. I've tried to do what you have told me but it doesn't converge. I've a question, Is the way to fix the temperature correct? Because in the tutorial, the temperature of the heater is variable and I want to fix it.

Thanks you
Hi barbara,

i think temperature is fixed for heater in tutorial case. it differ from patch to other but is fixed for each patch (simulate constant wall temperature).

i hope it helps you.
Ahmed Khattab is offline   Reply With Quote

Old   October 28, 2013, 15:12
Default
  #5
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
Hi barbara,

please send me your case files, as attached or URL for dropbox.

thanks
Ahmed Khattab is offline   Reply With Quote

Old   October 29, 2013, 06:52
Default
  #6
New Member
 
Bárbara Arizmendi
Join Date: Oct 2013
Location: Spain
Posts: 6
Rep Power: 2
Barbara is on a distinguished road
Hi Ahmed,
Here it's my case files.
https://www.dropbox.com/s/87qse1np1o...mpleHeater.zip

I think in the tutorial the value of T is fixed on the floor (500 K), and the heater changes its T value.
Barbara is offline   Reply With Quote

Old   November 5, 2013, 05:57
Default
  #7
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
Hi barbara,

sorry to be late. you have mistake in your makeCellSets.setSet in last line
Code:
cellZoneSet Air new setToCellZone bottomAir
you must change bottomAir to Air.

i didn't finished reviewing your case i will feed you back once finished.

good luck.
Ahmed Khattab is offline   Reply With Quote

Old   November 5, 2013, 11:13
Default
  #8
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
Quote:
Originally Posted by Barbara View Post
I think in the tutorial the value of T is fixed on the floor (500 K), and the heater changes its T value.
for the tutorial case the heater haven’t homogeneous temperature. only one patch exposed to higher temperature then it heats up solid heater then air and other solids.
Ahmed Khattab is offline   Reply With Quote

Old   November 6, 2013, 06:17
Default
  #9
New Member
 
Bárbara Arizmendi
Join Date: Oct 2013
Location: Spain
Posts: 6
Rep Power: 2
Barbara is on a distinguished road
Hi Ahmed,
I've already found my mistake. I got fix the T value of the heater. I changed the value of the internal field in the changeDictionarydict file. This is my script:

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      changeDictionaryDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dictionaryReplacement
{
    boundary
    {
        minY
        {
            type            wall;
        }

    }

    T
    {
        internalField   uniform 500;

        boundaryField
        {
            ".*"
            {
                type            fixedValue;
                value           uniform 500;
            }
            "heater_to_.*"
            {
                type            compressible::turbulentTemperatureCoupledBaffleMixed;
                neighbourFieldName T;
                kappa           solidThermo;
                kappaName       none;
                value           uniform 500;
            }

        }
    }
}

// ************************************************************************* //
I've also put a big value of Cp in order to have a fixed value in the heater. Is there any other way to fix this value?

Do you think chtMultiRegionFoam is proper to simulate natural convection?

Thanks

Bárbara
Barbara is offline   Reply With Quote

Old   November 6, 2013, 11:13
Default
  #10
Senior Member
 
Ahmed Khattab's Avatar
 
ahmed
Join Date: Feb 2010
Posts: 157
Blog Entries: 1
Rep Power: 6
Ahmed Khattab is on a distinguished road
Quote:
Originally Posted by Barbara View Post

Do you think chtMultiRegionFoam is proper to simulate natural convection?
if you want to simulate natural convection, you better use one of boussinesq solvers.
Ahmed Khattab is offline   Reply With Quote

Reply

Tags
boundary conditions, multiregionheater

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
Question about heat transfer coefficient setting for CFX Anna Tian CFX 1 June 16, 2013 06:28
symmetry boundary conditions in cfx lost.identity CFX 41 May 22, 2013 07:21
Low Mixing time Problem Mavier CFX 5 April 29, 2013 00:00
boundary conditions and mesh exporting vaina74 Open Source Meshers: Gmsh, Netgen, CGNS, ... 2 May 27, 2010 09:38
Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 2 July 15, 2005 04:15


All times are GMT -4. The time now is 03:11.