# velocity in Shan-chen multicomponent

Hello all
I simulated a droplet in channel with MCMP Shan-Chen lattice Boltzmann code. Now, I want to validate it with analytical solution. As we know, In S-C MCMP we have two distribution functions. I want to know how density and viscosity is calculated for the droplet? Is it true that density in each area Is summation of density of two component?(rho=rho[1]+rho[2]) or about viscosity(
mio=rho[1]*nu[1]+rho[2]*nu[2]?
Many thanks in advance and with kind regards

Hey Ehsaan

I think the below paper might be useful to you

http://staff.ustc.edu.cn/~huanghb/Huang_Sukop76_066701.pdf

. But I myself need help from you. Even I have written a MCMP Shan Chen Code(using the instructions given in Sukop’s book). I am trying to simulate a drop in periodic BCs. But unfortunately , the drop dissolves.
Could you please let me know, what are the parameters u used, like the G, the viscosity ratios and the initial radius. Did you also use Sukop’s book to write the code?
I have been stuck on this problem for the last two months, but to no avail.I would be highly grateful if you could help.

Hello visha
MCMP Shan Chen use for equal ratio density that means rho1=rho2.
for high ratio viscosity you can read " HaiboHuang,LeiWang,EvaluationofthreelatticeBoltzmannmodelsformultiphaseflowsin
porousmedia,ComputersandMathematicswithApplications61(2011)3606–3617" .
When tau1 and tau2 are different, the balance or equilibrium
density rho1 and rho2 would not equal again (bottom of page 3613).
Once you have know the equilibrium rho1 and rho2, you can restart your simulation but
set the initial rho1 and rho2 to be the equilibrium ones. Then you will observe that
the volume of the drople or the bubble would not change anymore.

Dear Ehsaan