Discovery Live Convection in Air – extremely high surface temperature

- July 2, 2019 at 6:47 am
  
  dirk.linnenbruegger
  Subscriber
  
  Dear Forum,
  
  Actually, I’ve set up a simple structure based on an IC with attached heatsink.
  
  I set plastic to the IC body and aluminium to the heatsink. The ambient temperature is defined with 40°C.
  
  The heat flow of the IC body is set to be 30 W and the convection in air parameter remains to the default value of 10 W/m2C.
  
  Running the static thermal analysis I wonder about the extremely high temperature inside the IC body which is in the range up to 710°C. Also the heatsink is very hot, starting with a temperature of 466°C at the body faces. This temperature range seems to be not realistic.
  
  Once I change the convection in air temperature to 200 W/m2C the overall temperature of this set-up decreases dramatically to a normal range of 50-120°C.
  
  So, I would like to know whether I did a systematically error in the simulation set-up or are special requirements which must be taken into account using the convection in air temperature.
  
  Thank you for any advise and comments.
- July 2, 2019 at 11:10 am
  
  Naresh Patre
  Ansys Employee
  
  Hello dirk. linnenbruegger
  
  I checked the images and noticed that the temperature contours ( min and max temperature locations) are not matching in both cases. Since you are only changing the convection coefficient, the location of maximum temperature should be the same in both the cases. In the case of convection coefficient 10 W/m2C, it looks like the max temperature region is at the corners of the IC body which doesn't look correct.
  
  I have tried to replicate your problem on a test case where I could see the same temerature contours (min and max temperature locations) upon changing convection coefficient from 10 W/m2C to 60 W/m2C. Please find attached this test model for your reference.
  
  Can you check if heat flow was correctly assigned to same body in both cases that you referred? Will it be possible for you to share the model for further investigation?
  
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