Laminar flow simulation in rotating domain

rahulv · November 12, 2011, 02:55

Hi everyone

I am doing simulation of rotating cylinder in air at low rpm . there is a heat source inside the cylinder and i want to dissipate heat.
For this simulation i am considering a rotating fluid domain around the cylinder of some thickness, can anyone suggest me what should be the thickness of the rotating domain and how many inflation layers i should consider inside it.

rv

ghorrocks · November 13, 2011, 17:02

If in doubt simulate a range of values and do a sensitivity analysis on it. That way you can be sure you are capturing what is important in your application rather than the opinion of somebody on a forum who does not really know what you are modelling.

nasir.iitd · June 1, 2014, 06:49

Rahul,
Glenn Horrocks is correct. Apart from that number of inflation layers will depend on minimum size and max. size of mesh in your domain and growth factor.If min. size is 0.2mm, max size is 2mm and growth factor is 1.2, then 0.2*1.2^(m-1)=2:
where m-1=>number of layers required.
Nasiruddin

nasir.iitd · July 8, 2014, 03:29

Hi Rahul,
I'm also doing the similar kind of work but not getting expected result. Can you share the boundary condition you have set i.e cell zone condition, vel. inlet, outlet and wall?
Thanks in advance.

flotus1 · July 8, 2014, 10:46

If the physical setup is a rotating heated cylinder (I wonder what the other boundary conditions are), then I doubt that the correct computational setup is a rotating domain.
A rotating boundary condition on the cylinder wall sounds better to me.

nasir.iitd · July 8, 2014, 12:05

Dear Flotus1,
I'm working in Fluent (Ansys-14.5). Can you please tell how to set rotating boundary in Fluent.My domain cylinder along with water flow inside rotates and treated as rotating solid cylinder.
Thanks in advance.

flotus1 · July 9, 2014, 03:14

Quote:

Originally Posted by flotus1

(I wonder what the other boundary conditions are)

To be more precise, I wonder what ecactly you are trying to model, which results you expect and how exactly the solutions you got so far differ from your expectations. Be descriptive...

nasir.iitd · July 9, 2014, 06:19

Dear Flotus1,
I want to do LES modelling of rotating turbulent pipe flow.Main features to calculate are RMS vel.(x,y&z), Mean vel.(x,y&z),Dissipation rate ,turb. kinetic energy decay and to get energy spectrum to study energy transfer mechanism. To compare these parameters between rotating pipe and stationary pie flow.

November 12, 2011, 02:55	Laminar flow simulation in rotating domain	#1
rahulv Member Rahul Vaibhav Join Date: Nov 2009 Location: India Posts: 33 Rep Power: 16	Hi everyone I am doing simulation of rotating cylinder in air at low rpm . there is a heat source inside the cylinder and i want to dissipate heat. For this simulation i am considering a rotating fluid domain around the cylinder of some thickness, can anyone suggest me what should be the thickness of the rotating domain and how many inflation layers i should consider inside it. rv

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November 13, 2011, 17:02		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	If in doubt simulate a range of values and do a sensitivity analysis on it. That way you can be sure you are capturing what is important in your application rather than the opinion of somebody on a forum who does not really know what you are modelling.

June 1, 2014, 06:49		#3
nasir.iitd Member SHEIKH NASIRUDDIN Join Date: Aug 2013 Location: DELHI Posts: 52 Rep Power: 12	Rahul, Glenn Horrocks is correct. Apart from that number of inflation layers will depend on minimum size and max. size of mesh in your domain and growth factor.If min. size is 0.2mm, max size is 2mm and growth factor is 1.2, then 0.2*1.2^(m-1)=2: where m-1=>number of layers required. Nasiruddin

July 8, 2014, 03:29		#4
nasir.iitd Member SHEIKH NASIRUDDIN Join Date: Aug 2013 Location: DELHI Posts: 52 Rep Power: 12	Hi Rahul, I'm also doing the similar kind of work but not getting expected result. Can you share the boundary condition you have set i.e cell zone condition, vel. inlet, outlet and wall? Thanks in advance.

July 8, 2014, 10:46		#5
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	If the physical setup is a rotating heated cylinder (I wonder what the other boundary conditions are), then I doubt that the correct computational setup is a rotating domain. A rotating boundary condition on the cylinder wall sounds better to me.

July 8, 2014, 12:05		#6
nasir.iitd Member SHEIKH NASIRUDDIN Join Date: Aug 2013 Location: DELHI Posts: 52 Rep Power: 12	Dear Flotus1, I'm working in Fluent (Ansys-14.5). Can you please tell how to set rotating boundary in Fluent.My domain cylinder along with water flow inside rotates and treated as rotating solid cylinder. Thanks in advance.

July 9, 2014, 06:19		#8
nasir.iitd Member SHEIKH NASIRUDDIN Join Date: Aug 2013 Location: DELHI Posts: 52 Rep Power: 12	Dear Flotus1, I want to do LES modelling of rotating turbulent pipe flow.Main features to calculate are RMS vel.(x,y&z), Mean vel.(x,y&z),Dissipation rate ,turb. kinetic energy decay and to get energy spectrum to study energy transfer mechanism. To compare these parameters between rotating pipe and stationary pie flow.