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April 6, 2010, 23:48 |
Unable to get rid of skewness- divergence
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#41 |
New Member
Zaqie
Join Date: Jul 2009
Posts: 22
Rep Power: 17 |
Hi Simon,
Reply to post#37... Bad news!!....my simulation is diverging at velocities where calculations are absolutely necessary. I tried one more thing. Instead of the sharp wedge shaped tip, I gave a cut in the geometr., to see if it will help in reducing skew. It doesnt help. I tried increasing the node at collapsed end, reducing node numbers, nothing seems to work. Also tried collapsing only till the blade block and not till far field. Nothing worked. Is there any way out to control the tip? Please help. Regards Zaqie Reza |
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April 7, 2010, 11:56 |
Shifted Periodic
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#42 |
New Member
Andy Good
Join Date: Jul 2009
Posts: 11
Rep Power: 17 |
Simon,
Thanks again for the pointers on turbine meshing, I've been working through them and (as expected) have come up against some trouble (mainly just with the use of the O-grids). I don't want you to have to spell out each and every small step but if you could answer a few questions that would be great. 1) The use of the two quarter O-grids for the shifted periodic makes sense but I'm having trouble getting the same arrangement of edges in your picture. Would you make 4 splits around the blade first, then collapse the trailing edge and then use the O-grid function? or would you do it in a different order? 2) For the rounded section of the hub ('0' to '2' on your picture) have you first split along '2', then along the axis, and then used 2 quarter O-grids? The reason I ask, is that I've tried that and when I try to add the internal faces to the O-grid, the split propagates into the next blocks. Many thanks, Andy |
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April 10, 2010, 09:58 |
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#43 |
New Member
yi.ma
Join Date: Apr 2010
Posts: 6
Rep Power: 16 |
How to set periodic boundary with tetra-prism meshing .
Please help. Regards Zaqie[/QUOTE] |
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April 10, 2010, 10:32 |
periodicity
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#44 |
New Member
Zaqie
Join Date: Jul 2009
Posts: 22
Rep Power: 17 |
Go to “mesh tab => Global Mesh Setup => Set up Periodicity”
you can do it there. |
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April 10, 2010, 22:09 |
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#45 | |
New Member
yi.ma
Join Date: Apr 2010
Posts: 6
Rep Power: 16 |
Quote:
yes,i had done,but i can find nothing change. is there any sill in the opperation? my module is a semicolumn with a wind turbine balde in it. my step: mesh tab => Global Mesh Setup => Set up Periodicity=>Set up globle mesh=>mesh. is there something wrong? |
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April 11, 2010, 10:44 |
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#46 |
New Member
yi.ma
Join Date: Apr 2010
Posts: 6
Rep Power: 16 |
Thanks very much for your help. I've solve this problem.
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September 26, 2010, 23:28 |
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#47 |
New Member
ZhangChenkai
Join Date: Apr 2009
Posts: 1
Rep Power: 0 |
Thanks very much, I really appreciate that
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November 11, 2011, 13:56 |
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#48 | |
Member
Join Date: Sep 2011
Location: United Kigdom
Posts: 51
Rep Power: 15 |
Quote:
I have some questions about meshing for the 3d blade inside the periodic air volume. a) With the last meshing method asked by Zaqie, do I only get a surface mesh, i.e. for the blade and the for the walls? If so, how do I create a volume mesh? Because I want to study what happens to the flow downstream the turbine? b) Since I only have two blades, can I apply the same concept (periodic) to a 180 degree 'slice' volume? c) Do I have to use Multiple or Single reference frame? Is the whole volume rotating in this method? Thank you very much, best |
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November 15, 2011, 21:20 |
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#49 |
Senior Member
Simon Pereira
Join Date: Mar 2009
Location: Ann Arbor, MI
Posts: 2,663
Blog Entries: 1
Rep Power: 47 |
a) If you are doing 3D Hexa blocking, you get the volume mesh by default. Perhaps you do not have it displayed? Run a scan plane to see it or right click on blocking and check info to see how many hexas are in your model... If we just displayed all the hexas by default it would be an incomprehensible pile of mesh and would take a lot more memory to display it, so by default we display the faces and you can use scan planes to see thru the volume...
b) Yes, you could have 180 degree periodic... c) That depends on your model. In some cases you may have a rotating portion inside a shroud that is not periodic and not rotating... In that case you would create an artificial cylinder to be the boundary between the two regions... You would rotate the region inside the cylinder and not rotate the region outside. If you are just doing a blade passage you could probably assume the whole regions is rotating... Just remember that when you set up all your boundary conditions.
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December 4, 2011, 14:48 |
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#50 | |
New Member
luxingzhe
Join Date: Feb 2011
Posts: 25
Rep Power: 15 |
Quote:
really appreciate if you can give me some suggestions, i have been sturk here for one week~~ Best Regards, |
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Tags |
3d analysis, blade, rotating, turbine |
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