LATTICE BOLTZMANN SIMULATIONS OF MIXING ENHANCEMENT BY THE ELECTRO-OSMOTIC FLOW IN MICROCHANNELS

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1515-1518 ◽  
Author(s):  
JINKU WANG ◽  
MORAN WANG ◽  
ZHIXIN LI
Keyword(s):  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Potential Distribution ◽  
Electrical Potential ◽  
Mixing Enhancement ◽  
Lattice Boltzmann Methods ◽  
Osmotic Flow ◽  
Lattice Boltzmann Simulations ◽  
Simulation Results ◽  
Electro Osmotic Flow

The Lattice Boltzmann methods are used to study the mixing enhancements by the electro-osmotic flow in microchannel. Three sets of lattice evolution methods are performed for the fluid flow, for the electrical potential distribution, and for the concentration propagation. The simulation results show that the electro-osmotic flow induces y-directional velocity which enhances the mixing in microchannels. The mixing enhancement is related with the surface zeta potential arrangement and the external electric field strength.

Electroviscous Transport Problems via Lattice-Boltzmann

1997 ◽  
Vol 08 (04) ◽  
pp. 889-898 ◽  
Author(s):  
Patrick B. Warren
Keyword(s):  
Lattice Boltzmann ◽  
Convective Diffusion ◽  
Analytic Solutions ◽  
Simple Application ◽  
Lattice Boltzmann Methods ◽  
Osmotic Flow ◽  
The Moment ◽  
Transport Problems ◽  
Electro Osmotic Flow ◽  
Diffusion Problems

The application of lattice-Boltzmann methods to electroviscous transport problems is discussed, generalising the moment propagation method for convective-diffusion problems. As a simple application, electro-osmotic flow in a parallel-sided slit is analysed, and the results compared favourably with available analytic solutions for this geometry.

Time-Periodic Electro-Osmotic Flow With Nonuniform Surface Charges

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Hyunsung Kim ◽  
Aminul Islam Khan ◽  
Prashanta Dutta
Keyword(s):  
Zeta Potential ◽  
Analytical Model ◽  
Potential Distribution ◽  
Step Change ◽  
Creeping Flow ◽  
Function Technique ◽  
Osmotic Flow ◽  
Nonuniform Surface ◽  
Time Periodic ◽  
Electro Osmotic Flow

Mixing in a microfluidic device is a major challenge due to creeping flow, which is a significant roadblock for development of lab-on-a-chip device. In this study, an analytical model is presented to study the fluid flow behavior in a microfluidic mixer using time-periodic electro-osmotic flow. To facilitate mixing through microvortices, nonuniform surface charge condition is considered. A generalized analytical solution is obtained for the time-periodic electro-osmotic flow using a stream function technique. The electro-osmotic body force term is accounted as a slip boundary condition on the channel wall, which is a function of time and space. To demonstrate the applicability of the analytical model, two different surface conditions are considered: sinusoidal and step change in zeta potential along the channel surface. Depending on the zeta potential distribution, we obtained diverse flow patterns and vortices. The flow circulation and its structures depend on channel size, charge distribution, and the applied electric field frequency. Our results indicate that the sinusoidal zeta potential distribution provides elliptical shaped vortices, whereas the step change zeta potential provides rectangular shaped vortices. This analytical model is expected to aid in the effective micromixer design.

Thermal Effect on Microchannel Electro-osmotic Flow With Consideration of Thermodiffusion

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Yi Zhou ◽  
Yongqi Xie ◽  
Chun Yang ◽  
Yee Cheong Lam
Keyword(s):  
Charge Density ◽  
Thermal Effect ◽  
Temperature Difference ◽  
Electrical Potential ◽  
Ionic Concentration ◽  
Free Charge ◽  
Regular Perturbation ◽  
Osmotic Flow ◽  
Ionic Distribution ◽  
Electro Osmotic Flow

Electro-osmotic flow (EOF) is widely used in microfluidic systems. Here, we report an analysis of the thermal effect on EOF under an imposed temperature difference. Our model not only considers the temperature-dependent thermophysical and electrical properties but also includes ion thermodiffusion. The inclusion of ion thermodiffusion affects ionic distribution, local electrical potential, as well as free charge density, and thus has effect on EOF. In particular, we formulate an analytical model for the thermal effect on a steady, fully developed EOF in slit microchannel. Using the regular perturbation method, we solve the model analytically to allow for decoupling several physical mechanisms contributing to the thermal effect on EOF. The parametric studies show that the presence of imposed temperature difference/gradient causes a deviation of the ionic concentration, electrical potential, and electro-osmotic velocity profiles from their isothermal counterparts, thereby giving rise to faster EOF. It is the thermodiffusion induced free charge density that plays a key role in the thermodiffusion induced electro-osmotic velocity.

scholarly journals Evaluation of electro-osmotic flow in a nanochannel via semi-analytical method

2012 ◽  
Vol 16 (5) ◽  
pp. 1297-1302 ◽  
Author(s):  
Payam Jalili ◽  
Domairry Ganji ◽  
Bahram Jalili ◽  
Domiri Ganji
Keyword(s):  
Shear Stress ◽  
Analytical Method ◽  
Homotopy Perturbation Method ◽  
Numerical Solutions ◽  
Electrical Potential ◽  
Osmotic Flow ◽  
Homotopy Perturbation ◽  
Stress Profiles ◽  
Electro Osmotic Flow ◽  
Cation Distributions

In this paper, equations due to anion and cation distributions, electrical potential and shear stress profiles in a nanochannel are formed for 1-D electro-osmotic flow, and solved by homotopy perturbation method. Results are compared with numerical solutions.

scholarly journals Microflow Simulations via the Lattice Boltzmann Method

2011 ◽  
Vol 9 (5) ◽  
pp. 1128-1136 ◽  
Author(s):  
Nikolaos Prasianakis ◽  
Santosh Ansumali
Keyword(s):  
Exact Solution ◽  
Knudsen Number ◽  
Lattice Boltzmann ◽  
Order Of Convergence ◽  
Kinetic Equations ◽  
Closed Form Solutions ◽  
Lattice Boltzmann Simulations ◽  
Simulation Results ◽  
Boltzmann Method ◽  
Stationary Planar

AbstractThe exact solution to the hierarchy of nonlinear lattice Boltzmann kinetic equations, for the stationary planar Couette flow for any Knudsen number was presented by S. Ansumali et al. [Phys. Rev. Lett., 98 (2007), 124502]. In this paper, simulation results at a non-vanishing value of the Knudsen number are compared with the closed-form solutions for the higher-order moments. The order of convergence to the exact solution is also studied. The lattice Boltzmann simulations are in excellent agreement with the exact solution.

scholarly journals Simulation of Natural Convection in a Concentric Hexagonal Annulus Using the Lattice Boltzmann Method Combined with the Smoothed Profile Method

Mathematics ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 1043
Author(s):  
Suresh Alapati
Keyword(s):  
Fluid Flow ◽  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Research Work ◽  
Profile Method ◽  
Flow Intensity ◽  
Simulation Results ◽  
Boltzmann Method ◽  
Present Simulation

This research work presents results obtained from the simulation of natural convection inside a concentric hexagonal annulus by using the lattice Boltzmann method (LBM). The fluid flow (pressure and velocity fields) inside the annulus is evaluated by LBM and a finite difference method (FDM) is used to get the temperature filed. The isothermal and no-slip boundary conditions (BC) on the hexagonal edges are treated with a smooth profile method (SPM). At first, for validating the present simulation technique, a standard benchmarking problem of natural convection inside a cold square cavity with a hot circular cylinder is simulated. Later, natural convection simulations inside the hexagonal annulus are carried out for different values of the aspect ratio, AR (ratio of the inner and outer hexagon sizes), and the Rayleigh number, Ra. The simulation results are presented in terms of isotherms (temperature contours), streamlines, temperature, and velocity distributions inside the annulus. The results show that the fluid flow intensity and the size and number of vortex pairs formed inside the annulus strongly depend on AR and Ra values. Based on the concentric isotherms and weak fluid flow intensity at the low Ra, it is observed that the heat transfer inside the annulus is dominated by the conduction mode. However, multiple circulation zones and distorted isotherms are observed at the high Ra due to the strong convective flow. To further access the accuracy and robustness of the present scheme, the present simulation results are compared with the results given by the commercial software, ANSYS-Fluent®. For all combinations of AR and Ra values, the simulation results of streamlines and isotherms patterns, and temperature and velocity distributions inside the annulus are in very good agreement with those of the Fluent software.

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