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Smagorinsky method in AD lattice

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  • #8684
    hhan
    Participant

    Dear Community,

    I now want to use Smagorinsky method to simulate the convective diffusion problem of NS-coupled AD. I checked the source code and it seems that SmagorinskyBGKdynamics cannot be used for scalar lattices because this dynamic requires the calculation of momentum second moments. Do I need to apply LES to AD scalar lattices as well?

    There is also a TAU_EFF LES method to calculate Omega, what is the principle of this, is there a reference paper? How should I choose ExternalTauEffLESForcedBGKdynamics and SmagorinskyBGKdynamics?

    Thank you for reply!

    #8686
    FBukreev
    Keymaster

    Hello,

    you can couple turbulent NS simulation with AD using special coupler and AD dynamics.
    For AD lattice you can use the following descriptor and dynamics:

    using ADDESCRIPTOR = D3Q7;
    using MOMENTA = momenta::AdvectionDiffusionBulkTuple;
    using ADBulkDynamics = dynamics::Tuple,AdvectionDiffusionExternalVelocityCollision>;

    the coupler is declared as following:

    SuperLatticeCoupling coupling(
    LESADECoupling{},
    names::NavierStokes{}, sLatticeNS,
    names::Concentration0{}, sLatticeAD);
    coupling.setParameter::SMAGORINSKY_PREFACTOR>(0.15);
    coupling.setParameter::SCHMIDT>(0.05); // turbulent Schmidt number for stabilization
    coupling.setParameter::OMEGA_NSE>(converter.getLatticeRelaxationFrequency());
    coupling.setParameter::OMEGA_ADE>(converter.getLatticeRelaxationFrequencyFromDiffusivity(diffusivity));

    For the NS lattice you can apply standard SmagorinskyBGKdynamics.

    Best wishes
    Fedor

    #8687
    hhan
    Participant

    Dear Fedor,

    Thank you for your reply!

    Is the SCHMIDT number here physically dimensionless, or is it an empirical parameter?

    #8699
    FBukreev
    Keymaster

    Schmidt number is dimensionless and can be between 0 and 1. 1 means no stabilization, closer to zero is artificial diffusion higher.

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