Re: Physical and Lattice units

[robin.trunk]

Hi Alina,rnrn1)rnIn LBM the density differs from the pressure only by constants, you can find the relation in the LBconverter. Creating an output of physical density can be done by applying some arithmetic:rnphysDensity = charRho * latticeDensityrnYou can create your own output with AnalyticalXD objects and SuperLatticeFfromAnalyticalFXD. In your case it looks like this:rn

Code:

AnalyticalConst3D<T,T> rhoAnalytical(converter.getCharRho());rn SuperLatticeFfromAnalyticalF3D<T,DESCRIPTOR> rhoLatticeF(rhoAnalytical, sLattice);rn SuperLatticeDensity3D<T, ADDESCRIPTOR> latticeDensity(sLattice);rn vtkWriter.addFunctor(rhoLatticeF*latticeDensity);

rnrn2)rn

Quote:

In my opinion, these initial conditions fill the channel by liquid flow with density = 1000kg/m^3 and velocity = 0.01 m/s and I have to set boundary conditions in lattice units.

rnThats all correct. Usually the values rho=1 and u=(0,0,0) are used, this represents a domain filled with a fluid at rest.rnrnBestrnRobinrn