ENTROPY GENERATION THEORY?

For a case of flow and heat transfer through a porous media (or even a simple pipe), what is the entropy generation formulation used by Fluent? (Viscous dissipation is neglected in the case). The flow is laminar. Similarly, for pure conduction cases any refrence for the same.

Best Answer

  • kkonannavarkkonannavar Posts: 12Ansys Employee
    Accepted Answer

    Hello

    Fluent does not calculate the entropy generation, it is a derived quantity. You might want to look into references for the exact formula to derive the same. Unfortunately I would not be able to point you to that. The general formula would be: dynamic viscosity *(shear strain rate)^2. You may have to extract the quantities necessary for the calculation of the entropy generation. You might want to look into UDFs for that.

    Thank you

    Kishan.

Answers

  • kkonannavarkkonannavar Posts: 12Ansys Employee

    Hello

    Could you share in what context are you asking this question, as in, what specific problem are you trying to solve?

    Thank you

    Kishan

  • rajendraporrajendrapor Posts: 30Member

    @kkonannavar Thanks for the prompt response!!

    I wish to know the equation(s) Fluent uses to calculate the entropy generation for a case of flow (Delta P) and heat transfer (conduction & convection) through a porous media for laminar flow (viscous dissipation is neglected). Some references would also be highly appreciated. Since, without any proper reference in the user manual of Fluent (or anything similar) about the rate of entropy generation, one cannot adopt Bejan's formulations.

  • rajendraporrajendrapor Posts: 30Member

    @kkonannavar Thanks for the response!!

    The equations are well established and are given in A. Bejan's books/papers. So, I can write the UDF for post processing the results in form of entropy generation.

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