Units at simulation of Poiseuille profile. (Solved!!)

Hi community,

As a newbie to the lattice-boltzmann method (I use palabos) I have problems with unit conversions as well. I read Jonas Latt’s article on unit conversion I set the boundary velocity u_0,lb = 0.02 in the LBM simulation. And I am studying some examples as Poiseuille profile. And I validate my results with other examples as FDV.

Further I set the resolution number to 100 and

IncomprFlowParam parameters(
(T) 2e-2, // uMax
(T) 1000., // Re
100, // N

I changed of Reynolds’ number at Palabos, but I obtained the same velocities at center and same profile, but the viscosity (not physical) at plbLog.dat is different. At FDV the same case (Poiseuille profile) with the same Reynolds’ number (500 and 1000), and I got that the velocities at center and different profile are different.

I wrote the velocities in physical units at palabos, as

*multiply (
parameters.getDeltaX() / parameters.getDeltaT(),
*computeVelocityComponent(lattice, profileSectionP2, 0) )

But I still get the same results. At palabos, I don’t impose the dx and dt, as well as, the velocity in physical units and viscosity neither.

Please, Can someone help me about units at palabos.


Hi Community,

After reading the units.h file, I realized that
I can include velocity in physical units [m / s] too.

So far, I vary the values ​​of physical speed, and I do not see a direct relation with speed in units of lattice, since this was always constant (0.002) without none apparent change.

Can you tell me if I’m right?