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Creating a piece of house with heat source
Posted 02.11.2010, 05:32 GMT-4 8 Replies
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Hi,
We are french students. We have some difficulties to realize our project with Comsol.
We want to create a room of house with dimension : 1meter * 1meter * 1meter interior.
The walls are plywood with thick 0.015 meter.
We glue on the walls of extruded polystyrene with thick 0.020 meter.
We want to create an opening (window) of 0.45 meter * 0.40 meter on one wall.
Inside this room , there is a heat source (heater 100Watts/meter).
The goal of this project is to study the variations of the temperature field after the opening of the window and
conditions Indoor / outdoor.
please find enclosed a notice of shema.
We realize a 3D model with comsol but we have an error :
================================================================================
Avancement - Créer le maillage: Fri Oct 22 10:07:34 CEST 2010
================================================================================
Number of vertex elements: 48
Number of edge elements: 1059
Number of boundary elements: 26374
Number of elements: 90659
Minimum element quality: 0.2501
================================================================================
Avancement - Résoudre le Problème: Fri Oct 22 10:07:38 CEST 2010
================================================================================
fem.sol=femstatic(fem, ...
'init',init, ...
'symmetric','off', ...
'solcomp',{'w','T','v','u','p'}, ...
'outcomp',{'w','v','T','u','p'}, ...
'blocksize','auto', ...
'hnlin','on', ...
'linsolver','bicgstab', ...
'rhob',20, ...
'maxlinit',100, ...
'prefuntype','right', ...
'prefun','gmg', ...
'prepar',{'presmooth','vanka','presmoothpar',{'iter',1,'vankasolv','direct','seconditer',3,'relax',0.8,'vankavars',{'Pinl_chns'}},'postsmooth','vanka','postsmoothpar',{'iter',1,'vankasolv','direct','seconditer',3,'relax',0.8,'vankavars',{'Pinl_chns'}},'csolver','pardiso'}, ...
'uscale','none', ...
'mcase',[0 1]);
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 389780
Iter ErrEst Damping Stepsize #Res #Jac #Sol LinIt LinErr LinRes
1 0.00014 0.0001000 0.00014 2 1 2 1 0.0082 0.00041
Error:
Failed to find a solution:
The relative error is greater than the relative tolerance, for the direct solver.
Returned solution has not converged.
thank you
Kind regards
Aurélien and Thomas
We are french students. We have some difficulties to realize our project with Comsol.
We want to create a room of house with dimension : 1meter * 1meter * 1meter interior.
The walls are plywood with thick 0.015 meter.
We glue on the walls of extruded polystyrene with thick 0.020 meter.
We want to create an opening (window) of 0.45 meter * 0.40 meter on one wall.
Inside this room , there is a heat source (heater 100Watts/meter).
The goal of this project is to study the variations of the temperature field after the opening of the window and
conditions Indoor / outdoor.
please find enclosed a notice of shema.
We realize a 3D model with comsol but we have an error :
================================================================================
Avancement - Créer le maillage: Fri Oct 22 10:07:34 CEST 2010
================================================================================
Number of vertex elements: 48
Number of edge elements: 1059
Number of boundary elements: 26374
Number of elements: 90659
Minimum element quality: 0.2501
================================================================================
Avancement - Résoudre le Problème: Fri Oct 22 10:07:38 CEST 2010
================================================================================
fem.sol=femstatic(fem, ...
'init',init, ...
'symmetric','off', ...
'solcomp',{'w','T','v','u','p'}, ...
'outcomp',{'w','v','T','u','p'}, ...
'blocksize','auto', ...
'hnlin','on', ...
'linsolver','bicgstab', ...
'rhob',20, ...
'maxlinit',100, ...
'prefuntype','right', ...
'prefun','gmg', ...
'prepar',{'presmooth','vanka','presmoothpar',{'iter',1,'vankasolv','direct','seconditer',3,'relax',0.8,'vankavars',{'Pinl_chns'}},'postsmooth','vanka','postsmoothpar',{'iter',1,'vankasolv','direct','seconditer',3,'relax',0.8,'vankavars',{'Pinl_chns'}},'csolver','pardiso'}, ...
'uscale','none', ...
'mcase',[0 1]);
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 389780
Iter ErrEst Damping Stepsize #Res #Jac #Sol LinIt LinErr LinRes
1 0.00014 0.0001000 0.00014 2 1 2 1 0.0082 0.00041
Error:
Failed to find a solution:
The relative error is greater than the relative tolerance, for the direct solver.
Returned solution has not converged.
thank you
Kind regards
Aurélien and Thomas
Attachments:
8 Replies Last Post 14.11.2010, 11:03 GMT-5
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Posted:
1 decade ago
Bonjour Aurélien,
What are the boundary conditions that you apply? Could you post the mode file? I suspect that you're looking for a stationary solution with the heater up, but no way for the heat to escape..... meaning the temperature blows up to infinity when looking for a stationary solution, hence no solution can be found.
What are the boundary conditions that you apply? Could you post the mode file? I suspect that you're looking for a stationary solution with the heater up, but no way for the heat to escape..... meaning the temperature blows up to infinity when looking for a stationary solution, hence no solution can be found.
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Posted:
1 decade ago
Hi,
thank you for your answer,
we have a problem, we can not attach our comsol project on the forum
we have a message file size error (file 5000ko)
How can we send you our project?
We are not sure for the boudary conditions.We try open boundary for the window, and for the rest we choose Wall
We use heat transfert (htgh) and Navier-Stokes (chns).
kind regards
thank you for your answer,
we have a problem, we can not attach our comsol project on the forum
we have a message file size error (file 5000ko)
How can we send you our project?
We are not sure for the boudary conditions.We try open boundary for the window, and for the rest we choose Wall
We use heat transfert (htgh) and Navier-Stokes (chns).
kind regards
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Posted:
1 decade ago
Delete your mesh and solver sequence, then save the file. It should be less than 1MB now.
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Posted:
1 decade ago
Hi,
please find inclosed our project.
We created an air cube inside of plywood box
And we are not sure for the periodic boundary conditions for the opening.
We want to see the air movement between the inside room and outdoor through the window.
now, we have not realised the polystyrene insulation. We will add this polystyrene after.
thank you very much
kind regards
please find inclosed our project.
We created an air cube inside of plywood box
And we are not sure for the periodic boundary conditions for the opening.
We want to see the air movement between the inside room and outdoor through the window.
now, we have not realised the polystyrene insulation. We will add this polystyrene after.
thank you very much
kind regards
Attachments:
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Posted:
1 decade ago
I cannot open the model because I only have the newest version of Comsol here, which can open models from versions that are 3 years old, but not before that. I strongly recommend to contact your system administrator and switch to a newer version (v4.1) which is much more efficient and easier to work with.
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Posted:
1 decade ago
Hi,
We draw our project with Comsol 4.0a but we have a problem because the software interface is different.
We have seen the PDF "introduction to Comsol multiphysics".
It is difficult to find the rigth options for each elements. We have seen the PDF "introduction to Comsol multiphysics"
Plywood:
Density: 600kg/m^3
Thermal conductivity 0.12W/(m..K)
Heat capacity at constant pressure 2545 J/(kg.K)
Polystyrene:
Density: 1050kg/m^3
Thermal conductivity 0.036W/(m..K)
Heat capacity at constant pressure 1200 J/(kg.K)
Air:
Density: 1200kg/m^3
Thermal conductivity 0.026W/(m..K)
Heat capacity at constant pressure 710 J/(kg.K)
Do you have a tutorial to help us to understand the new version?
thank you very much
kind regards
We draw our project with Comsol 4.0a but we have a problem because the software interface is different.
We have seen the PDF "introduction to Comsol multiphysics".
It is difficult to find the rigth options for each elements. We have seen the PDF "introduction to Comsol multiphysics"
Plywood:
Density: 600kg/m^3
Thermal conductivity 0.12W/(m..K)
Heat capacity at constant pressure 2545 J/(kg.K)
Polystyrene:
Density: 1050kg/m^3
Thermal conductivity 0.036W/(m..K)
Heat capacity at constant pressure 1200 J/(kg.K)
Air:
Density: 1200kg/m^3
Thermal conductivity 0.026W/(m..K)
Heat capacity at constant pressure 710 J/(kg.K)
Do you have a tutorial to help us to understand the new version?
thank you very much
kind regards
Attachments:
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Posted:
1 decade ago
Hello Aurelien,
You have to think a bit about exactly what you want to model.
In practice, the casing will probably "leak" heat away through edges. If you want to take that into account, you have to make an estimation and add a small heat flux at some edges. What is the temperature outside? Is the heat source homogeneous through the block? Are you looking for a stationary solution or a time-dependent analysis? Etc, etc.
I definitely recommend doing a tutorial. Please contact your local sales office for one: www.comsol.com/contact/offices/
I took a look at your model and did a simple calculation on it, putting a heat source of 100 W/m^3 in the block and a heat flux to the outside through the window at a temperature of 10 degC, with a heat transfer coefficient of 5 W/m*K. I have not taken into account material properties, other effects, etc. You will have to think about that. I'm giving you the model as a starting point, but don't consider it to be holy.
Good luck!
You have to think a bit about exactly what you want to model.
In practice, the casing will probably "leak" heat away through edges. If you want to take that into account, you have to make an estimation and add a small heat flux at some edges. What is the temperature outside? Is the heat source homogeneous through the block? Are you looking for a stationary solution or a time-dependent analysis? Etc, etc.
I definitely recommend doing a tutorial. Please contact your local sales office for one: www.comsol.com/contact/offices/
I took a look at your model and did a simple calculation on it, putting a heat source of 100 W/m^3 in the block and a heat flux to the outside through the window at a temperature of 10 degC, with a heat transfer coefficient of 5 W/m*K. I have not taken into account material properties, other effects, etc. You will have to think about that. I'm giving you the model as a starting point, but don't consider it to be holy.
Good luck!
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Posted:
1 decade ago
Hi,
thank you very much for your answer,
We don't take into account "leak" heat away through edges because we have an isolation over the plywood.
the heat source is homogeneous through the block.
if we want a time-dependent analysis how can we do that?
Which coefficient we have to change if we want simulate open or close or half-open window?
We attach our project where we added the material properties (plywood and air).
Thanks again
thank you very much for your answer,
We don't take into account "leak" heat away through edges because we have an isolation over the plywood.
the heat source is homogeneous through the block.
if we want a time-dependent analysis how can we do that?
Which coefficient we have to change if we want simulate open or close or half-open window?
We attach our project where we added the material properties (plywood and air).
Thanks again
Attachments: