Turbulent kinetic energy

- March 11, 2020 at 2:38 pm
  
  tanujsrivastava28
  Subscriber
  
  Hello,
  
  I have confusion related to "k" in the turbulence model. I made a simple 3-d loop diameter 8 mm with the no-slip condition (no inlet and outlet). Flow is buoyancy-driven with the heater at the bottom and cooler at the top. I used the k-e RNG. When I see the velocity contours, I get to know zero velocity at the wall due to no-slip. But when I see the contours of turbulent kinetic energy, at the wall there is non-zero value of "k", but I thought it might be zero at the wall due to no-slip. (see image) Flow is asymmetric due to local buoyancy.
- March 12, 2020 at 2:34 am
  
  Keyur Kanade
  Ansys Employee
  
  Fluent work with zero gradient for k at the wall. So with k-e rng model you can see some non zero values.
  
  Please check documentation for more info.
  
  Regards,
  
  Keyur
  
  If this helps, please mark this post as 'Is Solution' to help others.
  
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- March 12, 2020 at 2:58 am
  
  tanujsrivastava28
  Subscriber
  
  I tried the same simulations with all k-e family and k-w family....its its not only k-e but all other model showing the similar pattern.
- March 13, 2020 at 4:44 am
  
  Keyur Kanade
  Ansys Employee
  
  Yes, it will show non zero.
  
  Request you to please go through documentation on how zero gradient for k at the wall is implemented.
  
  Below is the link for doc/help.
  
  Regards,
  
  Keyur
  
  If this helps, please mark this post as 'Is Solution' to help others.
  
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- March 13, 2020 at 8:56 am
  
  tanujsrivastava28
  Subscriber
  
  I saw in the document about it. But there is no mention of the difference in the case of forces flow and buoyancy-driven flow. As in the buoyancy-driven flow, there is asymmetry at the circumference, and that is my main concern, why is it not the same value along the circumference.