Smagorinsky method in AD lattice

[hhan]

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!

[FBukreev]

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

[hhan]

Dear Fedor，

Thank you for your reply!

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

[FBukreev]

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

[Author]

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