Fluids

Fluids

possibly a mistake in the source term of the turbulent dissipation rate

    • uceczw4
      Subscriber

      I find there is a possibe mistake in the source term of the transport equation of the turbulent kinetic energy dissipation rate (turbulence disperse model) (Eq. 14.378) when the Simonin model (Eq. 14.406) is used in the fluent theory guide . The alfa and density should not be multiplied in the last term at the right-hand side of Eq. 14.378 according to the article they referred.

    • DrAmine
      Ansys Employee

      I will need to check the original article referenced in the paper. Do you have some screenshots you can share here?

    • uceczw4
      Subscriber

       

      **The referenced articles are:

      Enwald, H., Peirano, E., Almstedt, A.-E., 1996. Eulerian two-phase flow theory applied to fluidization. International journal of multiphase flow 22, 21-66.

      Peirano, E., Leckner, B., 1998. Fundamentals of turbulent gas-solid flows applied to circulating fluidized bed combustion. Progress in energy and combustion science 24, 259-296.

    • DrAmine
      Ansys Employee

      Thanks. I will check.

    • DrAmine
      Ansys Employee

      I checked the paper you are referring to but it did not have the same equations numbering. Step back to the TKE Equation before going to the Dissipation .Just look to this term from the paper of Enwald:

       

      it is just added to the TKE equation of gas phase without getting multiplied with volume fraction. This is not the case in Fluent where the term get multiplied with alpha_g*rho_g and it has that already in the formulation. 

       

       

      Please explain which equations are you referring to and how you did the derivation.

    • uceczw4
      Subscriber

      Actually, the issue we're talking about is the transport equation of the turbulent kinetic energy dissipation rate rather than the TKE equation. So, instead of Eq. [122], you should refer to Eq. [123-124] in the article by Enwald et al. (the same as Eq. (151) in the article by Peirano and Leckner).

      The source of dissipation in Fluent theory guide is defined as:

      Note that the whole term at the right-hand side of the equation i represents the source term.

       

      In the article, it is defined as

      Here, the source term is .

       

      Please read carefully the figures in the last reply, and you can find the details of the derivation and comparison.

    • DrAmine
      Ansys Employee

      I am reading carefully the figure and I ask to also check the definition of the TKE source term in the paper too. The source term of TKE is aslo different. In your explanation you are assuning both are using the same formulation for TKE source term which is wrong.

    • uceczw4
      Subscriber

       

    • DrAmine
      Ansys Employee

      So the TKE term itself is different:  Kp/alpha_c*rho_c is not equalt to alhpa_c*rho_c/tau_cp. 

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