CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

chtMultiRegionSimpleFoam semi-transparent solid

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 1, 2017, 05:33
Default chtMultiRegionSimpleFoam semi-transparent solid
  #1
New Member
 
SoraKH's Avatar
 
Join Date: Aug 2017
Location: Belgium
Posts: 3
Rep Power: 4
SoraKH is on a distinguished road
Hello everyone,

First of all I apologize for my English which is not my native language.

That's my problem. For a project, I have to manage to simulate the radiation in a semi-transparent solid in OpenFoam (version 3.0+).

For now the geometry is not important, so my geometry is simply a cube (for hot gas) with an inlet, an outlet, 3 wall and the last face is the interface between the gas my second Hexahedron which represents the semi-transparent solid (a glass).

I have already succeeded in simulating the problem without radiation and with radiation in the gas with the fvDOM model but for the solid it is more complicated. I have the impression that OpenFoam does not make it possible to simulate a solid other than opaque. Would anyone know more?

I could see on one of the posts that there existed a mode Frozenflow. So I thought to assimilate my solid to a liquid and activate Frozenflow but here is the problem, the file thermoproperties for a liquid asks to specify a viscosity and a Prandtl. However, a glass has a viscosity which tends towards the infinite and therefore a Prandtl which also tends towards infinity (because Pr = mu * cp / kappa). How can I do this?

I also tried to customize this solver but without success because my knowledge in C ++ is too limited for now. If the solution is towards this path, can you help me?

I thank you in advance.

Regards,

V.
SoraKH is offline   Reply With Quote

Old   August 7, 2017, 09:13
Default
  #2
New Member
 
SoraKH's Avatar
 
Join Date: Aug 2017
Location: Belgium
Posts: 3
Rep Power: 4
SoraKH is on a distinguished road
Hello,

After carrying out some tests, I observe that the Frozenflow mode allows me to create a "solid" from a fluid.

I had the opportunity to check 2 cases. The first one where I do not take into account the radiation and I check well that the convection and conduction are identical to my case with a real solid and hot fluid. And the second case where I activate the radiation only in the hot fluid and there again I correctly check that everything corresponds to my case with a real solid.

So I decided to get to the heart of the problem, radiation in my solid semitransparent.

My first problem is to make the difference between fluid_to_solid and solid_to_fluid. For example, in the BoundaryRadiationProperties file that is located in the file constant / fluid / and constant / solid / well I do not know what difference I have to give between the 2 files.

In solid / BoundaryRadiationProperties:

boundaryField
{
". *"
{
Type boundaryRadiation;
Fashion lookup;
Emissivity uniform 0.837;
Absorptivity uniform 0.0;
Transmissivity uniform 0.9;
Value uniform 0.0; // dummy value
}

vitrage_to_gaz
{
Type boundaryRadiation;
Fashion lookup;
Emissivity uniform 0.837;
Absorptivity uniform 0.0;
Transmissivity uniform 0.9;
Value uniform 0.0; // dummy value
}

In fluid / BoundaryRadiationProperties:

boundaryField
{
". *"
{
Type boundaryRadiation;
Fashion lookup;
Emissivity uniform 0.6;
Absorptivity uniform 0.6;
Value uniform 0.0; // dummy value
}

gaz_to_vitrage
{
Type boundaryRadiation;
Fashion lookup;
Emissivity uniform 0.837;
Absorptivity uniform 0.0;
Transmissivity uniform 0.9;
Value uniform 0.0; // dummy value
}

For now I put the same thing in the 2 (the figures are those of the solid) but it seems strange to do like this because the properties of my fluid and my solid are different. So I do not know in which I have to change these numbers and insert those of the fluid.

Then, a few other questions persist and I found nothing conclusive in my research.

As I understand the code, the reflected part of a ray is reflected only diffused and not, like the Snell-Descarte theory, a reflected main ray and the rest in diffusion. Is it correct?
So, is there a way to take this into account (a main reflective ray)?

My other question is: how is the radiation transmission to the interface? Is the radiation be preserved on the other side (at the first cell at least), or is it diffused on the other side of my interface?

Your answer will allow me to tailor my problem or expand my report to explain how the problem is actually handled with OpenFoam.

Thank you in advance,

V.
SoraKH is offline   Reply With Quote

Reply

Tags
chtmultiregionsimplefoam, frozenflow, fvdom, glass radiation, semi-transparent solid

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
OpenFOAM - Radiation with Transparent Solid brzous OpenFOAM Running, Solving & CFD 2 September 13, 2016 04:18
Error - Solar absorber - Solar Thermal Radiation MichaelK CFX 12 September 1, 2016 06:15
[swak4Foam] mass conservation of solid phase violated when using groovyBC with twoPhaseEulerFoam xpqiu OpenFOAM Community Contributions 8 June 17, 2015 03:08
radiation in semi transparent melt daiga CFX 0 October 31, 2007 08:22
CFX4.3 -build analysis form Chie Min CFX 5 July 13, 2001 00:19


All times are GMT -4. The time now is 10:44.