Search found 63 matches

by tibich72
19 Jul 2011, 06:05
Forum: ElmerSolver
Topic: Legacy VTK saving in ElmerSolver v6.1
Replies: 4
Views: 3331

Legacy VTK saving in ElmerSolver v6.1

I've recently upgraded ElmerSolver from version 5.5.0 to version 6.1 (as displayed with 'elmersolver -v') and there seem to be some important differences in how the legacy vtk files are written. I'm using this .sif fragment to write vtk files: Solver 3 Exec Solver = After Simulation Procedure = &quo...
by tibich72
02 May 2011, 21:25
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

Forgot to mention: the distance between the fins in the direction of the air flow is 3.25cm.
by tibich72
02 May 2011, 21:12
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

Hi Peter, thanks for the feedback. As I've mentioned, I'm not an expert in thermal analysis, so can't answer your questions regarding laminar flow and Reynolds number. I'm including the .sif file, maybe it has the answers to your questions. Header CHECK KEYWORDS Warn Mesh DB "." "demo...
by tibich72
02 May 2011, 18:27
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

The last slice picture:
velocity_slice_46mm.jpg
Slice 1mm above the top of the heatsink
(53.3 KiB) Not downloaded yet
Thanks,
Tibi
by tibich72
02 May 2011, 18:26
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

I've re-modeled the heatsink to have only 5 fins in the direction of the airflow, with plenty of space between the fins. heatsink3d.jpg This time I've done the simulation on a simplified system model, which had only the airbox and this new heatsink (no other components -- the model discussed above h...
by tibich72
30 Apr 2011, 01:31
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

In the slice through the middle of the fins I can see at least 7 triangles on a few spot checks -- so I assume 7 tetrahedras. That's a good suggestion (starting with fewer fins), but it's still strange there's no flow. Unfortunately, for now, I cannot go with a much finer mesh than 308K elements bec...
by tibich72
29 Apr 2011, 22:55
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

> The normal velocity should be set to zero by some means, there are more than one way to do that though. I've tried all combinations of setting/not setting the velocity and "normal-tangential velocity", but I'm stumped. Basically when I set "normal-tangential velocity", the enti...
by tibich72
29 Apr 2011, 18:07
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

I've searched in the documentation for Steady State Iterations and, in the examples, it's always set to 1. Probably the sif file was created from examples in the documentation, so that's why it's one. I've also looked at Solver 4 (the KEpsilon solver), and it has the line "Exec Solver = Never&q...
by tibich72
29 Apr 2011, 17:47
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

That's part of the inheritance, I don't know why it's that number of iterations. Is there a better value that I should put there? For the boundary conditions between air and solids, I've set the wall law to true and set the boundary thickness, but did not set the velocity to zero. It did show air go...
by tibich72
28 Apr 2011, 22:52
Forum: ElmerSolver
Topic: Cooling problem
Replies: 27
Views: 14981

Re: Cooling problem

Right, sorry, I should've started with the geometry. Here's the system without the air box: 3d_view.jpg So, I have a component (at the bottom, with the rounded edges) and on top of it is a heatsink (the one with a lot of rectangular fins -- it's not the most performant heatsink out there, just somet...