# Temperature issue during modeling cooling plate using Star CCM+

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 August 20, 2021, 06:14 Temperature issue during modeling cooling plate using Star CCM+ #1 New Member   Yibao Shang Join Date: Jun 2014 Location: China Posts: 15 Rep Power: 10 Hey guys, I was modeling a fluid zone inside a cooling plate. The fluid zone has an inlet and an outlet. I set an constant inlet flow rate of about 0.5 kg/s (corresponding to 0.5 L/s considering liquid parameter) with constant temperature of 280 K. The outlet is set as pressure outlet with 0 Pa. The models of the fluid I chose are implicit unsteady、segregated flow and segregated fluid temperature. The initial temperature of the fluid zone is 298 K. The volume of the fluid zone is about 8 L. What confused me is the calculation result: The outlet temperature remained nearly constant (298K) for about 40 s，until the cold fluid from inlet reached outlet (which can be observed from temperature scalar). However, as the flow rate is 0.5 L/s and the total volume is 8 L, it takes at most 16 s to replace all the initial fluid with cold fluid from inlet, in theory. That means outlet temperature has to decrease after 16 s, not 40 s. Can someone enlighten me about this issue? Are there something unsuitable models chosen that can cause this problem?

August 20, 2021, 07:40
#2
Senior Member

Arjun
Join Date: Mar 2009
Location: Nurenberg, Germany
Posts: 1,150
Rep Power: 30
Quote:
 Originally Posted by tjushang Hey guys, I was modeling a fluid zone inside a cooling plate. The fluid zone has an inlet and an outlet. I set an constant inlet flow rate of about 0.5 kg/s (corresponding to 0.5 L/s considering liquid parameter) with constant temperature of 280 K. The outlet is set as pressure outlet with 0 Pa. The models of the fluid I chose are implicit unsteady、segregated flow and segregated fluid temperature. The initial temperature of the fluid zone is 298 K. The volume of the fluid zone is about 8 L. What confused me is the calculation result: The outlet temperature remained nearly constant (298K) for about 40 s，until the cold fluid from inlet reached outlet (which can be observed from temperature scalar). However, as the flow rate is 0.5 L/s and the total volume is 8 L, it takes at most 16 s to replace all the initial fluid with cold fluid from inlet, in theory. That means outlet temperature has to decrease after 16 s, not 40 s. Can someone enlighten me about this issue? Are there something unsuitable models chosen that can cause this problem?

most probably the energy equation did not converge enough during the time step. You can double the inner iterations and see if this time reduces from 40s. If this reduces then what i wrote is the reason.

August 22, 2021, 22:43
#3
New Member

Yibao Shang
Join Date: Jun 2014
Location: China
Posts: 15
Rep Power: 10
Quote:
 Originally Posted by arjun most probably the energy equation did not converge enough during the time step. You can double the inner iterations and see if this time reduces from 40s. If this reduces then what i wrote is the reason.
Thank you arjun! I doubled the iteration steps and it was observed that temperature field spread faster than before. It seems that it was the lack of iterations or the overlong time step that caused this problem.

Allow me to ask more: how can we tell if the iteration step is enough by simply seeing residuals? My normalized residuals of energy decreases by only 1 order of magnitude and it almost takes a lot of total iteration steps to finish whole simulation I desired. How to balance the accuracy and time cost is really a important matter to me.

 Tags cooling plate, star ccm+, temperature equation

 Thread Tools Search this Thread Search this Thread: Advanced Search Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post granzer Main CFD Forum 5 February 21, 2020 04:47 arun1994 STAR-CCM+ 1 January 25, 2017 11:04 shashank312 FLUENT 0 August 24, 2011 13:44 Ashok kumar FLUENT 1 January 13, 2009 04:34 Amir Khodabandeh FLUENT 1 March 16, 2007 02:51

All times are GMT -4. The time now is 04:11.

 Contact Us - CFD Online - Privacy Statement - Top