Application of lattice Boltzmann method to the fluid analysis in a rectangular microchannel

The lattice Boltzmann method (LBM) is a computation and modeling method different from traditional numerical methods. It has unique features that other numerical methods do not have due to its micro-particle characterization. The present study includes solving cavity flow problems, writing graphical interface programs for two-dimensional nine-velocity (D2Q9) modeling, and drawing the collision and flow process with Reynolds number 400 and relaxation factor 1.5. The LBM led to the same converged solutions of cavity flow obtained by traditional computational fluid dynamics. In addition, LBM was also used to simulate pipe flow in a rectangular microchannel and investigate the effect of drag force, dielectrophoresis, and buoyancy on the motion of biological particles. The equation of motion for biological particles under drag force, dielectrophoresis, and buoyancy was utilized to simulate the pipe flow and microparticle flow in a microchannel. Spiral flow lines were clearly found near microelectrodes. The calculation was carried out for the pressure drop of fluids at concentrations of 0.13 to 10−6 M under 0.25 V AC field. Flow line diagrams were drawn for fluids under pressure gradients. The flow line diagram shows that a spiral pattern remains near the electrodes, whereas flow lines away from the electrodes move towards the right direction, when the pressure gradient is 102 and velocity of horizontal and vertical components is 6. This observation means that the biological particles inside the strong electric field are adsorbed on the electrodes, whereas those away from electrodes and inside the weak electric field are flushed out. Thus, this rectangular microchannel is able to separate biological particles. The simulation results from the study hopes to provide further understanding of electroosmotic flow and promote its application development in microelectromechanical systems and biomedical fields.