Topics relate to Fluent, CFX, Turbogrid and more

how to put the values for TKE and DISSIPATION RATE IN INITIALIZATION

    • Masooma_Qizilbash12

      hello all,

      I want to ask how I know the values to be enter in the initialization tab of ansys fluent package 2020 R2 for turbulanet kinetic energy and specific dissipation rate if i have a beaker and in beaker there is 1%PVA and 0.2 % PEI are mixing at the impeller speed of 5000 rpm total volume of the sytem is 1010 ml 1000ml pva and 10 ml pei.

      thank you



    • omkar.kulkarni
      Ansys Employee



      You will need some more parameters to calculate the TKE and specific dissipation rate. You can refer the following formulas and calculate it accordingly.

      1. TKE=1/2 (ρuu′)

      • TKE is the turbulent kinetic energy.
      • ρ is the density of the fluid.
      • u' represents the fluctuating velocity (the deviation of the local velocity from the mean velocity).

      2. ε=2μ/ρ[(xj/ui)(xj​/ui)]

      • ε is the specific dissipation rate.
      • μ is the dynamic viscosity of the fluid.
      • ρ is the density of the fluid.
      • (xj/ui) represents the velocity gradient in the fluid, with and denoting the different spatial coordinates.

      I hope this helps.




    • Masooma_Qizilbash12

      thank you Omkar for the reply,

      I want to know that I have only one velocity of 5m/s how can I calculate the velocity deviation from local velocity to mean what this gradient means also for TDR what is this velocity gradient because in a stirred tank impeller is moving with 5000 rpm only one velocity 

      I shall be thankful fo the help

      kind regards,


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