I was reading some threads about lattice units calculations, and there are some black holes I couldn’t figure out. I have a micromixer, there is an inner tube (velocity 0.05, diameter D) and an outer tube (velocity 0.02, 6 holes diameter D) which convey in a bigger channel (diameter 5D). Reynolds number 100 and lattice units reported in figure. The value of kinematic viscosity is suggested to be calculated as: 0.025*D/Reynolds. The density is equal to 0.5. 5 D= 70 lu and 300 micrometers.

I would like, first of all to understand how the value of density has been calculated.

Secondly, using the guide written by JLatt, I tried to calculate all the values, neglecting those provided by the teacher, I would like to ask if you agree on the choices made.

Length physical=5 D=70 lu = 300 micrometers.

I don’t have any information about the real velocity, I assume v0,p=0,385 m/s hence the physical time is: t0,p=0,000779 s (which seems quite low)

The physical viscosity for water is 1,156E-6 m^2/s and the Reynolds number is Re=100 (as the values suggested).

Assuming deltax=1/70 and deltat=deltax^2.

nilb=1/Re=0,01ts/lu^2 ( which does not make lot of sense, as for the dimensional analisys).

Hence tau=0,56 and u0,lb=0,0143 lu/ts.

Thank you in advance for any help

Antonio