CFD analysis has stopped becuse of solver exited unexpectdely

[cpatil365]

Hi Experts, My_design in CFD getting stopped unexpectedly as shown in pic attached. Whenever I enter the number of "iterations to run" 100, It runs up-to 82 and stops and gives the error. If I enter runs up-to 50 it stopes at 32 etc. I am unable to solve because the help at the below link does not help me. I did all the trials to resolve this. http://help.autodesk.com/view/SCDSE/2015/ENU/?caas=caas/sfdcarticles/sfdcarticles/Error-Message-Anal... Can anybody help on this ? Its very urgent as I am unable to produce the any results or to see the results. Many Thanks, Chandra

[cpatil365]

Hi Jon,

Thanks a lot for your help., I got some more clarification. Now I decided below BCs(boundary Conditions), as per your guidance.
-----------------------------------
1. Inlet : temp 22C; Surface Velocity: 50m/s
2. Outlet : pressure=0 psi
3. Base of the Heat Sink : Heat Flux: 4500w/m2
4. Mesh : manual 0.3
----------------------------------
pls correct me for the above BCs. My aim is to measure the heat at the Fin of the Heat sink, and the base of the heat sink, after the simulation is done. Because I am supplying constant of about 4500W/m2 Heat flux. I want to make another experiment that : I want to supply the Temperature of 70C at the base surface of he heat sink. want to know how much heat is dissipates in the Base and the Fin, after simulation. Could you guide me, how can I do that ? what are boundary conditions required.

Secondly, do we have contours views after simulation on the Heat sink body ? If so pls point me the tutorials.

Many Thanks,
Chandra

[Jon.Wilde]

Great!

Our tutorials are here: Simuation CFD tutorials.

You could swap the heat flux for a temp I'm sure.

Thanks,

Jon

[cpatil365]

Hi Jon,
Thanks again. I have few more questions here:

1. I am seeing the mesh is not applied to air block I created. Is that compulsory ? I am only interested in the heat sink base and fins temperatures. If meshing is important on air mesh. How much needs to be applied ?

2. I was asking you in last mail that : "Contours view" means, The different temperature numbers will appear on the 3D body of the heat sink( solids), That will look like oil map. is this feature available in Auto-desk CFD ?

3. I am not getting what u mean by CAD ? use of the "inventor Professional 2015" for drawing sketches ? I am finding a big difficulty on next experiments that. I am bringing different kinds of heat sinks, under same air block hood. And testing the simulations. Problem is : whenever I am making assembly . The air block is ok. but newly bought heat sinks gets turned to opposite axis from what that is. Hope I built all kind of heat sinks, like that. But in assembly, there is no scale remains on the diagrams/air blocks, after we measure. I am facing difficulty, in putting the heat sinks where I want and turning axis, will be not synchs with exact 90 degrees.etc. any help on this ?

4. I want to apply the air surface velocity at the inlet , by Renolds number. do you think below calculation can bring the Renolds number ?
http://www.engineeringtoolbox.com/reynolds-number-d_237.html

Many Thanks,
Chandra

[Jon.Wilde · Accepted solution]

Hi Chandra,

To answer your questions:

1. You must  mesh the air. There are no real rules apart from a minimum of 4-5 elements through a gap. Run it, refine it to 0.7 and see if the results change by more than 5%, if they do, keep refining until your results are independent of the mesh. The air mesh is going to be more important than the solid
2. Yes, right click on the Legend and change the options
3. Draw both the heat sink and a solid block that will be the air in CAD - you literally only need two parts. Drawn in CAD they will be read into CFD the same every time
4. Should be OK - you can look in the Summary File for the Reynolds Number that CFD sees to verify 😉

Thanks,

Jon

[cpatil365]

Hi Jon,
Thanks alot for your great help.

I am finding issues still as below:

1. The mesh sizing with air as 200 and the Heatsink as 0.1 , taking few hours to produce results. Will this happen just because of the Server heavily loaded? I have my computer with 8GB ram and Windows 7, with Intel Core Duo (4 Cores) processor laptop, still facing issues, sometimes it comes with less memory issue. I have 40GB free disk.


2. Could you pls post me any example of "Counter views" , I am unable to get by right clicks on the results body.


Many Thanks,
Chandra

[Jon.Wilde]

Hi Chandra,

Sure thing.

Can you share an image of a cut-plane through the model showing the mesh?

Why not just use the auto mesh and refine it a bit? A mesh size of 200 and 0.1 doesn't make sense to me, are you still working in inches?

If you have 8GB of RAM, you should be able to run a model with approximately 4m elements, any more and you may fill the RAM and start using a page file, which is obviously slow.

Right click on the Results Legend and go to Options to change the settings. This will effect the Global Results (which can be selected with a right click in the graphics window, off of the model).

Thanks,

Jon

[cpatil365]

Hi Jon,
Thanks for the quick reply.

Why I chosen 200(air), 0.1(Heat Sink) is that , I thought the results will be quicker in few minutes. I am working in millimeter dimensions(MKS systems) now. One more compulsory requirement is all "total mesh elements" should be of 250,000, not more also. That is it. any values do you suggest for meshing now to get just around 250, 000 as total elements in mesh( Not Nodes)?

Many Thanks,
Chandra

[cpatil365]

If I am using "automatic meshing", Its showing me, 14906 Total Elements. I want little higher elements as of 250, 000. Pls help me. about 5-6 hours wasted with different guessing.

[Jon.Wilde · Accepted solution]

OK so select the volumes and refine the mesh. 

Can I suggest you run through some of our tutorials to learn how to do set these models up? There is a lot of information in the online help.

This is an example of how to refine a mesh.

Kind regards,

Jon

[cpatil365]

Many Thanks. My experiments started on this now.
a more question, just to confirm. I saw the car tutorial. there the Inlet BC is applied a volumteric flow Velocity , NOT the Surface Velocity. In my case I am using the Surface velocity as my inlet BC. Is that OK for my case ?? what are the differences here ?

[Jon.Wilde]

They are both applied to the inlet surface but one is a velocity (for example m/s) and the other is a volumetric flow rate (for example m^3/s).

Does that make sense?

[cpatil365]

My only question is in my case which is applicable ? If I apply volumentric velocity Hope it takes much time, for solving too ?

[srhusain]

Hi:

Either volumetric flow rate or velocity is applicable- note that volumetric flow rate is simply the velocity x the inlet area.

[cpatil365]

Hi Jon,

Thanks again. I am still not getting hold of the Mesh number elelemnts. . That is going here and there.

Any more adavannced  tutirials, on getting controlling exact elements ?  I tried "adavanced options", nothing helpfull. 

Best Reagrds,

Chandra

[Jon.Wilde]

Hi Chandra,

It is first best to assume that the approximate element count is just that, very approximate. So mesh models (run for 0 iterations to do this without solving) to check out the mesh and the mesh count.

Have you tried the basics and comparing the differences?

Mesh autosize

Mesh a slightly refined model (refining the air by 0.7)

Then try uniform meshing some parts and seeing what that looks like.

You can also right click on a part to see the surface mesh preview if it helps.

Kind regards,

Jon

[cpatil365]

Hi Jon,

I have solved now, my refineing and making approximate control of the elements. Many Thanks.

 I have another dificulty here. Pls find my designed Heat sink. when I bring to CFD,  its showing me that surafaces and edges should be removed. I removed them. But Simulataion is not happening.

 Becuse Unassigned materials. I did suppress them. But If i remove the whole Heat sink disappers in CFD. is my Heatsink structure not acceptable by CFD software here ?

 Pls advice.

Best Regards,

[Jon.Wilde · Accepted solution]

Hi,

Firstly you file will not open so I cannot check it.

If you have unassigned materials in CFD - assign a material to them.

Only use the small object and edge tool if you think it is necessary - are they very small edges/objects?

The design is so simple I would be surprised if it was anything other than CFD making split edges into one solid edge.

Thanks,

Jon

[cpatil365]

Hi Jon,

 Thanks alot for the help.  However,  I could get the results well. Ony issue was if I open the CFZ file deirectly for the one I sent you latest, Hestsink( club shaped, holes in it).

That gives core-dump/tool crash issue for CFD tool.  I need to open from Inventer then re-assign all the materials and then alll BCs, and  then Mesh. Then Only every time i can get results.

leave it.  I got results some how.

 I have few more questions:

1. Is this Autodesk is "FEM" tool ? or Anyltical Modles used or Compacts models used ? 

2. Can I see these models in any form . Isf so, can you point me how to see them ?

Best Reagrds,

Chandra