Recently,I used the multiphase program based on Xing’s single phase model to simulate the mix of gas and water. Under without external force and body force.it was a good results.
but now,when i tried to add the body force ,there was a problem .And i think the question is that the form of body force ‘rho*g(j)’ is not correct or something .
So i simulated the static water in the tanker without the body force and the result:no velocity is yielded in the tanker.
but when i simulated static water in the tanker with the body force and the result a unkown down velocity is yielded in the tanker.
I used the paper of “Discrete lattice effects on the forcing term in the lattice Boltzmann method” the form of the body force is:
the LBE can read
f(i) = (1 -1/tau) * f(i) + 1/tau* feq(i) +F(i)
the quilibrium velocity uu and the fluid velocity u is given as follow
rhouu= rhou =sum_fe+rhog/2
where tau is the relaxation time, w(i) lattice weights, e(i,j) lattice speeds, u(k) fluid speed, cs sound speed, rho*g(j) physical force and F(i) lattice force.
If someone had used Guo’s body force model and please tell me if the form of body force is not right or something is wrong?
thanks in advance