# Thermal cooling analysis

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November 25, 2016, 05:12
Thermal cooling analysis
#1
New Member

sanju
Join Date: Nov 2016
Posts: 19
Rep Power: 7
Hello

Kindly I request to go through the problem and find the below attached files.

I have considered a cylinder with 4 holes inside for the air to flow inside.

Pressure based solver with transient condition.
#Problem statement.
1. Cylinder is rotating at 250 rad/sec.
2. Air is flowing inside with 8 m/s.
3. I have defined the cylinder surface temperature 0f 400K.
4. Need to do the cooling analysis of the problem.

Kindly suggest me where I am doing wrong.
# struggling with the time step.
Attached Images
 DM.jpg (39.5 KB, 19 views) mesh.jpg (106.9 KB, 13 views) solution controls.jpg (73.2 KB, 11 views) solution method.jpg (80.6 KB, 9 views) time step 1.jpg (75.6 KB, 10 views)

November 25, 2016, 05:14
#2
New Member

sanju
Join Date: Nov 2016
Posts: 19
Rep Power: 7
these attachments followed with the above problem.
Attached Images
 time_step_2.jpg (108.1 KB, 9 views) temp counter for time step 0.0005.jpg (101.3 KB, 8 views) temp_counter for time step_02.jpg (108.6 KB, 10 views) Capture.jpg (107.3 KB, 8 views)

 November 27, 2016, 01:39 #3 New Member   sanju Join Date: Nov 2016 Posts: 19 Rep Power: 7 Any experts, Please guide me. I believe this is the best portal to learn the concept. I am student please guide me.

December 3, 2016, 11:07
#4
New Member

sanju
Join Date: Nov 2016
Posts: 19
Rep Power: 7
Hi all again,

Find the attached files, which shows the temp-contours.
From this what I understood is only air getting heated up and surface temperature is constant.

Is it fluent taking continuous temperature to surface of cylinder....?

I want to give only once temp to cylinder.

Attached Images
 hole temp-inlet.PNG (21.6 KB, 5 views) temp_contour.PNG (69.3 KB, 3 views)

 December 3, 2016, 15:47 #5 Senior Member   SinaJ Join Date: Nov 2009 Posts: 136 Rep Power: 14 Well, - first of all your geometry seems to be huge! I don't know what's the application but a cylinder with diameter of ~5m, is way big to be rotating at almost 2500rpm! - Your boundary conditions (BCs) seem ambiguous. if you set the surface temperature BC as T=400K, why would you expect it do decrease during the solution? If you are looking to see some sort of change on the surface, you can apply a constant flux and see temperature change by running the air stream. - It seems that your flow is turbulence. but I don't see any prism layers in your mesh! you mesh. IMO your mesh is too coarse for that problem. especially near wall regions. Consider y+ between 30 and 300, if you're using k-epsilon. - If those 4 small cylinders are holes, why do you have mesh inside them?! I think before moving forward, you need to read some tutorials for similar applications.

 December 4, 2016, 03:58 #6 New Member   sanju Join Date: Nov 2016 Posts: 19 Rep Power: 7 Thank you sir for your valuable reply. I will try with the heat flux. -If those 4 small cylinders are holes, why do you have mesh inside them?! I heard that where ever there is air flow, there also we should have volume mesh. If I am wrong kindly guide me. The purpose of my problem is, I want to cool the cylinder after some interval by giving initial surface temperaure.

 December 6, 2016, 02:34 #7 New Member   Join Date: May 2016 Posts: 3 Rep Power: 7 try smaller energy under-relaxation factor