# mesh deformation

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 November 24, 2010, 07:38 mesh deformation #1 New Member   Join Date: Nov 2010 Posts: 10 Rep Power: 8 Sponsored Links hello everyone, i have problem involving cylindrical wafer getting polished by 2 plates(opposite rotational velocity) top and below. there is a water flow from top plates through nozzles to cool the process. i have to simulates this problem. with this wafer rotate with the plates with an angluer velocity. i set this domain to mesh deformation , define the plates BC to rotating wall with + and - velocity. and for wafer BC to mesh motion with specific displacement with cylindrical components .on cylindrical components i mention theta as distance between center of axis and center of wafer. and getting a error with negetive volume. please if some one can guide me ,if im on right direction or not. i'm new to CFD im using this for my thesis.so please explain me little bit in layman terms. i had read all the tutorial they dont have anythign for this perticular type of problem. http://www.edr.no/blogg/ansys_blogge...cfx_re_meshing i want similar effect with the rotational velocity. and im learning CEL little bit.

 November 24, 2010, 17:49 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,732 Rep Power: 106 Can you post a drawing of what you are doing?

November 26, 2010, 12:04
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Quote:
 Originally Posted by ghorrocks Can you post a drawing of what you are doing?
http://yfrog.com/j2polisherj
http://yfrog.com/3dpolisher1j

here is ther drawing of similar polishing machine this is with less details, i hope you understand what i'm talkin about.

because of wafer rotaions ,im planning on using mesh deformation.
some suggest to use adaptive mesh refinment(but i dont know how to do this in ansys 12.1-cfx)

top and low plates have a 2m diameter and space between wafer and plates is 5e-6mm, because of this 2 extreme parameters some suggest it can't be done because of too many nodes to simulate.

in real case there will be more nozzle for fluid inlet to cool down the process.

please let me know if u need more details. sorry if bad technical wordings.

 November 27, 2010, 05:44 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,732 Rep Power: 106 Can you explain what you are trying to learn by doing a simulation? What is the important physics of what you want to do?

 November 27, 2010, 18:21 #5 New Member   Join Date: Oct 2010 Posts: 9 Rep Power: 8 thanx for the reply. This is a polishing tool for glass or plastic lens(wafer).because of the polishing at higher speed, the polishing surface will get heated ,this will make the unevenness in polishing plate surface, this will contribute to the unevenness in lens(wafer). so we try to learn the temperature distribution along the plate. this might help to control the speed of polishing and control the injection of cooling water to keep the temperature at desired amount.

 November 27, 2010, 20:53 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,732 Rep Power: 106 OK, now I see what you are doing. So really all you want to know is how the coolant controls the temperature of the grinding. I suspect the rotation does not play an important role. You can probably run this ignoring the rotation. Then it is just a normal CHT simulation.

 November 28, 2010, 06:07 #7 New Member   Join Date: Oct 2010 Posts: 9 Rep Power: 8 thanx for the quick reply. i have to ask some basic question please forgive me,ok but how temperature will increase if there no rotations are defines in grinding(friction between the plates and wafer cause the temperature increase) and my prof is looking forward to see the mesh deformation(AMR) type of simulation.

 November 28, 2010, 07:46 #8 Member   Fabian E. Join Date: Nov 2009 Posts: 36 Rep Power: 9 I also think there's no need for a mesh deformation simulation. In any case you have to apply a definition for the friction coefficent. You can set the heat production by a CEL expression as a function of the tangential velocity (again CEL). This heat production should be applied as energy source in a small subdomain adjacent to your interface. I never done this, but I think that should work. Don't set the heat source at your interface - that will result in a jump (saltus) of your temperature profile over your interface.

 November 29, 2010, 06:42 #9 New Member   Join Date: Oct 2010 Posts: 9 Rep Power: 8 thanx galap, ok i will try this.do you have a CEL manuel,similar to UDP manuel.there is non in ansys customer portal.

 November 29, 2010, 18:21 #10 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,732 Rep Power: 106 Sorry, yes I forgot to mention. No need for moving mesh and probably no need for rotating frames of reference either. But the heat source can be applied to the outer face of the solid, just as a standard boundary condition. No need to apply it to a solid region. The CEL functions are explained in the CFX reference manual.

 December 1, 2010, 07:49 #11 New Member   Join Date: Oct 2010 Posts: 9 Rep Power: 8 hi thanx ,for the replay. but CHT simulation what you suggest it works for single way rotation,mine is more like a earth rotating around the sun,with multiple self rotations. i think this wont reflect in CHt simulation, please correct me if im wrong.

 December 1, 2010, 17:50 #12 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,732 Rep Power: 106 You will have to show a diagram which shows what you are talking about. Your previous diagrams did not suggest any counter rotation was required.

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