Fluids

Fluids

Turbulent kinetic energy

    • srivastavatanuj
      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.


       



       

    • 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.


      Guidelines on the Student Community


      How to access ANSYS help links


       

    • srivastavatanuj
      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.

    • 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.


      Guidelines on the Student Community


      How to access ANSYS help links


       

    • srivastavatanuj
      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. 


       

Viewing 4 reply threads
  • You must be logged in to reply to this topic.