LBM for Microfluidics

What is LBM?

Lattice Boltzmann method (LBM) is a class of computational fluid dynamic (CFD) problem used to simulate dynamics of fluids in mesoscopic scale (between microscopic and macroscopic scale). Because of the natural parallelism and easy implementation of multiphase and multiphysics, they are becoming popular for problems such as microfluidics.


How LBM solves?

LBM view the fluid as sets of discrete number of particles moving with the random directions and speed. The exchange of momentum and energy is achieved by collision and streaming among the particles. The probability of the particle distribution fi in discrete space (x) at discrete time (t) is calculated by solving the following equation in each lattice points

The left hand side of the equation represents streaming process and right hand side describes the collision process. The relaxation time τ (τ>0.5) is related to the viscosity of the fluid and equilibrium distribution function is a function of density of the fluid.


What are the LB models?

The equilibrium distribution function (feq) and the discretization strategy are based on the choice of the LBM model. The popular LBM models are defined based on the dimension and direction of propagation of the particles. They can be one, two or three dimensional in nature.

In our Lab, we have developed a LBM based tool for microfluidics problems. The Software is developed on open source platform with Graphical user interface (GUI).

The implementation and results are available in the following manuscripts.

T Pravinraj and Rajendra Patrikar.  ”Modelling and investigation of partial wetting surfaces for drop dynamics using lattice Boltzmann method.” Applied Surface Science, Volume 409, (2017): 214-222. (DOI:

T Pravinraj, and Rajendra Patrikar. “Modeling and characterization of surface roughness effect on fluid flow in a polydimethylsiloxane microchannel using a fractal based lattice Boltzmann method.” AIP Advances 8.6 (2018): 065112.

T Pravinraj and Rajendra Patrikar “Splitting and Transport of a Droplet with no external actuation force for Lab on Chip devices”, 21st International Symposium on VLSI Design & Test (VDAT) Symposium, June 29- July 2, 2017, IIT Roorkee, India

The software for modeling surface roughness and LBM tool for fluid dynamics are developed in our lab and available.

GUI window for surface roughness modeling tool

GUI window for LBM fluid dynamics tool

                                                                     LBM results for droplet splitting

The user manuals for the developed tools are available here.(User manual for surface roughness modeling tool: Manual For Surface Roughness(User manual for LBM fluidics tool: Manual For LBM Fluiddynamics )