Hello,

I know that LBM is stemed from lattice gas(LG). So, to what extent is it capable for modeling of liquid flows???however, i saw papers that shows it’s application in non-newtonian fluids, free surface and also EDL in micro-device. I think we must add a source term for implementation of inter-molecular forces. Please send here your comments.

Thank you

Hello nanolb,

what exactly are you interested in? Which is the relevant length scale for you? millimeters, micrometers, nanometers? Which inter-molecular forces are you talking about? Surface tension for example?

Please be more specific, because LBM and its applications make up a vast field.

Timm

many flows in engineering are described by the navier-stokes equation. it offers a valid approximation for gases as well as fluids. it doesn’t matter if the theory is based on gases or fluids, as long as you are sure to solve the navier-stokes equation. this is not true any more if you want complex fluids. then, indeed, you need to be more specific with your question.

Dear Tim,

Hello,

Thank you for your reply. I want to model nanofluids in Macro system. As you know, Nanofluids are dispersion of metallic nanometer size

particles (<100nm) into a base fluid. Many researchers take nano-fluids as one-component fluid and model it with only consideration of specific properties that mixture gain like 1st article that i send it to your email. so please check your email.

But i see only one article that embraces this problem with consideration of nanofluids as 2-component mixture like 2nd article that i send i to you.they use Shan and Chen model.

I do not really like to take it as 2-component model. But i want to use a lattice BGK thermal model like:

1-Xiaoyi He, Shiyi Chen, and Gary D. Doolen, “A

Novel Thermal Model for the Lattice Boltzmann

Method in Incompressible Limit”, Journal of

Computational Physics 146, 282–300 (1998)

or 2-Zhaoli Guo, Baochang Shi, Chuguang Zheng, “A

coupled lattice BGK model for the Boussinesq

equations”, Int. J. Numer. Meth. Fluids 2002;

but i want to put properties of nanofluids by the formulae that are supposed to be true for mixture(like 1st paper(but they do not use LBM)).

My questions:

1-overall question-for a macro-system(large size) like a heat-exchenger

is there any difference between liquid modeling or gas modeling!!!

or their difference are their time relaxation that is viscosity influence on it.

Is my question weird???

I think for liquid flow, we must take a source term for inter-molecular forces.(new idea)

2-are these two thermal models capable of modeling systems with different Pr,

Thank you for your time,

Sincerely yours,

Hello nanolb,

regarding your first question:

Using LBM you can model fluids in general (gases and liquids) which obey the Navier-Stokes equations. This is what Adam has already written. If you have large Mach numbers or large Knudsen numbers, the LBM is not a good method for the simulations. So you cannot model dilute gases with LBM.

I’m not familiar with modeling thermal conductible fluids using the LBM. So I am not the appropriate person for help. I assume that the choice of the model (one component or two components) critically depends on the exact observations you are interested in.

Do you have some experience using LBM? If not I suggest that you begin with a review paper, e. g.

Chen, Doolen. lattice Boltzmann method for fluid flows. Annual Reviews in Fluid Mechanics, 30 (1): 329-364, 1998.

Maybe some of your questions are answered or you get new ideas. Most probably there is even a newer and good review paper I am currently not aware of.

Best,

Timm