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Closed Discrepancy in results - Running with "laminar" turbulence model, and running with RAS + "turbulence off"
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  • Discrepancy in results - Running with "laminar" turbulence model, and running with RAS + "turbulence off"

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  • Closed Issue created

    Summary

    Results obtained by running a simulation using the turbulence model laminar does not match with results obtained by running with the option RAS coupled with turbulence off

    Steps to reproduce

    Run the simulation case attached with:

    • Allrun.lam
    • Allrun.turbOff

    This can be generalized to running any incompressible (tested only for incompressible cases) first with laminar and compare with results obtained by running with RAS and turbulence off

    Example case

    002_turbOff_Laminar_Discrepancy.tar.gz

    What is the current bug behaviour?

    The result obtained by running the case with laminar is different from the result obtained by running the case with RAS + turbulence off

    What is the expected correct behavior?

    The results obtained from both configurations should be the same.

    Relevant logs and/or images

    -NA-

    Environment information

    OpenFOAM version : 1812

    Operating system : CentOS 7

    Compiler : GCC 4.8.5

    Possible fixes

    The problem comes from the initialization of the nut field.

    When the case is run using laminar, the viscosity is taken from the transport properties. However, when the case is run using RAS with turbulence off, the nut field is initialised using the initial values of k and omega / epsilon, but not updated anymore during the simulation.

    This results in a different effective viscosity being used for cases run with turbulence off.

    Is this something intentional? Was the switch turbulence on/off implemented with some other intention in mind other than to give a simple method to switch between laminar and turbulent simulations?

    ## Reattaching the author to the issue ticket: @philippose ##

    Edited

    Linked items ... 0

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