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Body to Body Radiation One Enclosure

9 REPLIES 9
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Message 1 of 10
ehtesham.bokhari
676 Views, 9 Replies

Body to Body Radiation One Enclosure

Hello,

I have an enclosure with difference surfaces as difference materials (emmisivity)

Heat enters from one surface, I want to conduct 

BODY to BODY radiation simulation.

attached is my setup, I am getting an error. Please help me to get it fixed.

*.fem file is also attached as compressed file.

Please check my attached setup.

Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
9 REPLIES 9
Message 2 of 10

 

Hello,

 

Unfortunately, the .fem file is not the complete model. What you need to do is follow the procedure in the post "Create, Post, or Provide an Archive of your model".

 

Your model looks small, so I am guessing that it does not take very long until the error message appears. But if it does take more than a few minutes before the error occurs, please let us know what the error message is.

 

Thanks.

Message 3 of 10

Hello Mr. John Holtz

 

Attached is my archive file (as zip) and yes, its a small model. I have kept the mesh size very big untill, all the errors are removed from the setup.

Let me tell you a bit about it. 

It is One enclosure, with all six sides of different materials and different (emissivity)

 

Surface controlled temperature is applied from one side and the radiation inside the enclosure is to be studied. as well as the convection from the other sides.

 

Please check the attached archive and remove the errors.

 

Thank You

Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
Message 4 of 10

Below is the error message I am getting. Plus I have attached my archive file as zip in the above post. Please check to identify the mistake I have made in this model.

 

 

** Model [E:\Inventor Working Files\Radiation simulation\Radiation in Fiber design\Assembly Radiation of lower enclosure.ds_data\1\ds] done

Autodesk (R) Simulation Surface-to-Surface Radiation Management
Version 2014.00.00.0513-W64/X64 22-Feb-2013
Copyright (c) 2013, Autodesk, Inc. All rights reserved.

Model [E:\Inventor Working Files\Radiation simulation\Radiation in Fiber design\Assembly Radiation of lower enclosure.ds_data\1\ds] opened for checking/generating radiation data...

Getting data for enclosure 1.

Creating surfaces for enclosure 1.

 

Error: surface with a zero area!
Check face 1 of element 146 in goup 4 .


2014/02/18-14:04:24 Model [E:\Inventor Working Files\Radiation simulation\Radiation in Fiber design\Assembly Radiation of lower enclosure.ds_data\1\ds] closed

 

Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
Message 5 of 10

Hello,

 

Can any one please help me. 

I have attached my archive file in the post above, its a small model. Please help me removing the error out of it

 

Thanks

Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
Message 6 of 10

 

Hi Ehtesham,

 

Your first error says "Error: No enabled surfaces in enclosure [2]!". Someone created a new enclosure (number 2) under the body-to-body radiation dialog. Because there are no surfaces assigned to that enclosure, the software (and I) are confused. Why would you create a radiation enclosure if there is nothing in it? 😉

 

The solution is to go into the body-to-body radiation dialog, use the drop-down arrow to look at enclosure 2, and uncheck the box that says "Enclosure participates in calculation". In other words, you do not want to include enclosure 2 in the calculation. (If there were a way to delete it, that's what you would really do. Since there is no delete feature, all you can do is remove it from the calculation.)

 

After fixing that, you will receive an error that says "surface with a zero area! Check face 1 of element 146 in goup 4". I do not understand what is causing this problem. It might be a software bug, or it might be a software limitation. You can probably avoid the error by defining the radiation surfaces by Part number and Surface number instead of Part number and All surfaces.

 

In my opinion, your mesh is way too coarse to get an accurate answer. Maybe even too coarse to get an inaccurate answer! Because the model is long and skinny (a length to thickness ratio of about 70 to 1), my suggestion is to create a 2D model by hand and ignore the effects that occur at the ends. (If you need to include the end effects, you can do a 3D model to approximate the end effects at a later time.) You have a 4-sided, thin wall, hollow tube. It should take about 5 minutes to build the model and have results. (Of course, something always goes wrong so that it takes longer than I think it should. 😉

 

Because all of the sides are thin, your other option is to use plate elements instead of brick elements. A hand-built mesh would be best, but you can use your CAD model and do either a midplane mesh, or a plate/shell mesh and delete the outside surfaces.

 

Good luck.

Message 7 of 10

Hello,

Thanks for the time and the reply.
I removed the second enclosure.
I change my Mesh size to 60% from 110%
I also change the parts to Plates from Brick

and now I am getting this error

Error. **** Error: insufficient memory in sparse assembly
what does this mean ?

--
Regards
Ehtesham
Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
Message 8 of 10

Hello,

 
Thanks for the time and the reply.
I removed the second enclosure.
I change my Mesh size to 60% from 110%
I also change the parts to Plates from Brick
 
and now I am getting this error
 
Error.  **** Error: insufficient memory in sparse assembly
what does this mean ?
Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis
Message 9 of 10

 

I assume that this occurred during the analysis and appeared in the analysis window. The error indicates that the software could not access enough computer memory (RAM) to solve the the model.

 

If you were running the analysis while other heavy-memory programs were opened (Inventor, etc), then I suggest that you try running the analysis again with just Sim Mech running. In fact, you may want to try it after the computer has been re-started/re-booted (just to make sure the memory is cleaned out).

 

I'm not sure that I believe the error message, but do not have any other suggestions. 😞

Message 10 of 10

Thank You

 What does this error mean ?
 
  • where have I defined Tolerance?
  • where can I find this surface 1270 and surface 1271 etc etc
 
 
Creating surfaces for enclosure 1.
 
 Writing temporary binary files for enclosure 1.
 
 Calculating view factors for enclosure 1.
 
 Error: view factors sum = 1.16649 must be >= 0 and < 1
        (tolerance used=0.1) for an open enclosure.
        This is not the case for surface 1270!
        Refine mesh or try the string rule/contour integration method.
 
 Error: view factors sum = 1.3 must be >= 0 and < 1
        (tolerance used=0.1) for an open enclosure.
        This is not the case for surface 1271!
        Refine mesh or try the string rule/contour integration method.
 
 
 
 
Ehtesham Bokhari
PhD Student
Thermal and CFD Simulation Analysis

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