Printing the relaxation time of each lattice to vtk files

[guojuw]

Hi,

I know the way to print the velocity of each lattice to vtk files:

SuperLatticePhysVelocity2D<T, DESCRIPTOR> velocity(sLattice, converter);
vtkWriter.addFunctor(velocity);

Since I am dealing with non-Newtonian fluids, can I print the lattice relaxation time to vtk files in a similar way?

Junwei Guo

[Nicolas]

Dear Junwei Guo,

you can print any analytical functor via SuperLatticeFfromAnalyticalF2D. In case a constant value needs to be written an AnalyticalConst2D can be used to provide the respective functor. Even though you are probably not interested in writing a constant lattice relaxation time to every cell, this could be achieved by the following snippet:

AnalyticalConst2D<T, T> anaConstTau( converter.getLatticeRelaxationTime() );
SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> tau( anaConstTau, sLattice );
vtmWriter.addFunctor( tau );

Best,
Nicolas

• This reply was modified 4 years, 8 months ago by Nicolas.

[guojuw]

Hi Nicolas,

I mean printing the non-constant relaxation time from non-Newtonian modeling, for example, the power-law case in $openlbRoot/examples/laminar/powerLaw2d.

In other words, I just want to see the relaxation time from each cell at any time step if I am using the DynOmegaD2Q9Descriptor.

Regards,
Junwei Guo

[Aurelio H]

Hi Guo,

The descriptor that you are using stores omega in an external field. You may see it in file src/dynamics/dynOmegaLatticeDescriptors.h, where DynOmegaD2Q9Descriptor is defined.

I would suggest using:

SuperLatticeField3D<T,DESCRIPTOR,OMEGA> omegaLB (sLattice);
vtkWriter.addFunctor(omegaLB);

This would print the relaxation frequency (omega) in lattice units to the VTK file. Is this what you are looking for?

Cheers,
Aurelio

[guojuw]

Dear Aurelio,

Great! Thanks a lot. It helps me.

Regard,
Junwei Guo

[Author]

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