A coupled immersed boundary and immersed interface method for interfacial flows with soluble surfactant

2018 ◽  
Vol 168 ◽  
pp. 201-215 ◽  
Author(s):  
Wei-Fan Hu ◽  
Ming-Chih Lai ◽  
Chaouqi Misbah
Keyword(s):  
Immersed Boundary ◽  
Interfacial Flows ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Soluble Surfactant

Parametric Study of Dielectrophoretic Interactive Motion of Particles

2015 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Matthew J. Benton ◽  
Prashanta Dutta ◽  
Robert Dillon
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Electric Field ◽  
Free Particle ◽  
Immersed Boundary ◽  
Label Free ◽  
Navier Stokes Equation ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Fluid Medium

Dielectrophoresis (DEP) has become one of the most popular mechanisms for label free particle manipulations and transport in microfluidics. The efficacy of this mechanism is greatly dependent on the understanding and control of DEP interactive motion among particles. In this study, we performed a systematic investigation to understand the effect of particles size and electrical properties on DC DEP interactions among particles using in-house hybrid immersed boundary – immersed interface numerical method. Immersed boundary method is employed to predict flow field and immersed interface method is used to simulate electric field. The numerical model utilizes Maxwell’s stress tensor to obtain DEP forces, while solving transient Navier-Stokes equation it determines the hydrodynamic interaction between each of the particles and the fluid containing them. By varying the number of particles as well as the particles’ size, electrical properties and initial orientations, a number of possibilities were considered. Results indicate that the particles with similar electrical conductivities attract each other and tend to align themselves parallel to the external electric field regardless of sizes. If electrical conductivity of particles is lower than that of the fluid medium then the particle-particle interactions is caused by the negative DEP. If electrical conductivity of particles is higher than that of the fluid medium then the interactive motions of particle is attributed to the positive DEP. On the other hand, electrically dissimilar particles still attract each other but tend to align perpendicular to the electric field. Both negative and positive DEP contributes in interactions between electrically dissimilar particles. Numerical simulation also shows that the identical sized particles move at the same speed during interaction. In contrast, smaller particles moves faster than the larger particle during the interactions. This study explains the effect of size and electrical properties on DEP interactive motions of particles and can be utilized to design microfluidic devices for DEP particle manipulations.

FROM IIM TO AUGMENTED IIM: A POWERFUL TOOL FOR COMPLEX PROBLEMS USING CARTESIAN MESHES

2018 ◽  
Vol 3 (1) ◽  
pp. 1-6
Author(s):  
Zhilin Li
Keyword(s):  
Discontinuous Coefficients ◽  
Immersed Boundary ◽  
Governing Equations ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Cartesian Meshes ◽  
Sharp Interface Method ◽  
Improve Accuracy ◽  
Ib Method ◽  
Multi Scales

The immersed interface method (IIM) ?rst proposed in is an accurate numerical method for solving elliptic interface problems on Cartesian meshes. It is a sharp interface method that was intended to improve accuracy of the immersed boundary (IB) method. The IIM is second order accurate in the maximum norm (pointwise, strongest) while the IB method is ?rst order accurate. The ?rst IIM paper is one of the most downloaded one from the SIAM website and is one of the most cited papers. While IIM provided a way of accurate discretization of the partial differential equations (PDEs) with discontinuous coefficients, the augmented IIM ?rst proposed in made the IIM much more efficient and faster by utilizing existing fast Poisson solvers. More important is that the augmented IIM provides an efficient way for multi-physics models with different governing equations, problems on irregular domains, multi-scales and multi-connected domains. A brie?y introduction of the augmented strategy including some recently progress is presented in this article.

Numerical Investigation of DC Dielectrophoretic Particle Transport

2014 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Prashanta Dutta ◽  
Robert Dillon
Keyword(s):  
Electric Field ◽  
Immersed Boundary Method ◽  
Particle Transport ◽  
Suspended Particles ◽  
Immersed Boundary ◽  
Immersed Interface Method ◽  
Particle Assembly ◽  
Immersed Interface ◽  
Boundary Method ◽  
Fluid Media

In this paper, we investigate the mechanism of two dimensional DC dielectrophoresis (DEP) using a hybrid immersed interface-immersed boundary method where both electric and hydrodynamic forces are obtained with interface-resolved approach instead of point-particle method. Immersed interface method is employed to predict DC electric field in a fluid media with suspended particles while immersed boundary method is used to study particle transport in a fluid media. The Maxwell stress tensor approach is adopted to obtain dielectrophoretic force. This hybrid numerical scheme demonstrates the underlying physics of positive and negative dielectrophoresis, and explains their contribution in particle assembly with consideration of size, initial configurations and electrical properties of particles as well as fluid media. The results show that the positive DEP provides accelerating motion while negative DEP provides decelerating motion depending on the electrode configurations and initial particle positions. The results also show that the local nonuniformity in electric field induced by the suspended particles guides the particles to form stable chain. Both positive and negative DEP can contribute in the process of particle assembly formation based on the properties of particles and fluid media. This hybrid immersed interface-immersed boundary scheme could be an efficient numerical tool for understanding fundamental mechanism of dielectrophoresis as well as designing and optimization of DEP based microfluidic devices.

Dielectrophoretic Interactions and Chaining of Ellipsoidal Particles in a Microchannel

2016 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Partha P. Gopmandal ◽  
Prashanta Dutta ◽  
Robert Dillon
Keyword(s):  
Electric Field ◽  
Stress Tensor ◽  
Applied Electric Field ◽  
Immersed Boundary ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Ellipsoidal Particles ◽  
Clockwise Direction ◽  
A Chain ◽  
Final Orientation

Recent experimental studies report that the understanding of dielectrophoretic (DEP) interactions and chaining of irregularly shaped particles, particularly ellipsoidal shaped particle, are critical for development of smart materials, engineered biological cellular structure and tissue formation. This paper presents a comprehensive numerical investigation of direct current (DC) dielectrophoretic (DEP) chaining and interactions of ellipsoidal particles in a microchannel. A hybrid immersed boundary-immersed interface method is employed to explain the fundamental mechanism of DEP interactions and chaining of ellipsoidal particles. Electric field equations are solved by the immersed interface method while the immersed boundary method is employed to solve fluid equations. The DEP force was estimated by using Maxwell’s stress tensor (MST) and the Cauchy stress tensor (CST) was employed to evaluate hydrodynamic force. The results show that the electrical properties of fluid and particles are the main deciding factor on the final orientation of ellipsoidal particles. However the size, shapes and initial positions and orientations have significant impact on interaction time spans. Results also show that if the interacting particles are electrically similar i.e. having same electrical conductivity then they always form a chain parallel to the applied electric field, otherwise they form a chain which is orthogonal to the applied electric field. In parallel chaining, particles rotate in a clockwise direction, while in orthogonal (to the applied electric field) chaining, particles rotate in counter-clockwise direction to reach to the final orientation. Results also indicate that the ellipsoidal particles go through an electro-orientation process if initially the major axis of the ellipsoidal particles is not in perfect alignment with the applied electric field. The electro-orientation and DEP interaction take place simultaneously to reach to final stable orientation. This study provides critical insight on the mechanism of DEP interactions and chaining of ellipsoidal shaped particles.

An AC Dielectrophoretic Trap for Cellular Assembly

2013 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Robert Dillon ◽  
Prashanta Dutta
Keyword(s):  
Mathematical Model ◽  
Electric Field ◽  
Immersed Boundary ◽  
Computational Domain ◽  
Point Dipole ◽  
Dielectrophoretic Force ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Maxwell Stress Tensor ◽  
Ac Electric Field

A mathematical model and numerical techniques are proposed to study AC electric field induced cellular assembly in a microfluidic device. In the mathematical model, the Maxwell stress tensor is used to calculate the dielectrophoretic force acting on particles by considering the physical effect of particles in the computational domain. Thus, the proposed model eliminates the approximations used in point dipole methods for calculating dielectrophoretic force. The numerical method is based on hybrid immersed boundary-immersed interface methods. An immersed boundary method is used for the fluid equations and particle transport, while an immersed interface method is employed to obtain the AC electric field in a fluid media with suspended particles. For the immersed interface method, an iterative algorithm is developed to solve the complex Poisson equation using a real variable formulation. The decoupled algorithm for solving complex differential equations converges rapidly. The hybrid method is used to investigate the physics of AC dielectrophoresis in a cross-channel junction. The numerical results show that with proper design and appropriate selection of applied potential and frequency, global electric field minima can be obtained to facilitate multiple particle trapping by exploiting the mechanism of negative dielectrophoresis.

scholarly journals Vesicle electrohydrodynamic simulations by coupling immersed boundary and immersed interface method

2016 ◽  
Vol 317 ◽  
pp. 66-81 ◽  
Author(s):  
Wei-Fan Hu ◽  
Ming-Chih Lai ◽  
Yunchang Seol ◽  
Yuan-Nan Young
Keyword(s):  
Immersed Boundary ◽  
Immersed Interface Method ◽  
Immersed Interface

A Coupled Immersed Interface and Level Set Method for Three-Dimensional Interfacial Flows with Insoluble Surfactant

2014 ◽  
Vol 15 (2) ◽  
pp. 451-469 ◽  
Author(s):  
Jian-Jun Xu ◽  
Yunqing Huang ◽  
Ming-Chih Lai ◽  
Zhilin Li
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Stokes Equations ◽  
Small Neighborhood ◽  
Physical Parameters ◽  
Interfacial Flows ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Poisson Solver ◽  
Insoluble Surfactant

AbstractIn this paper, a numerical method is presented for simulating the 3D interfacial flows with insoluble surfactant. The numerical scheme consists of a 3D immersed interface method (IIM) for solving Stokes equations with jumps across the interface and a 3D level-set method for solving the surfactant convection-diffusion equation along a moving and deforming interface. The 3D IIM Poisson solver modifies the one in the literature by assuming that the jump conditions of the solution and the flux are implicitly given at the grid points in a small neighborhood of the interface. This assumption is convenient in conjunction with the level-set techniques. It allows standard Lagrangian interpolation for quantities at the projection points on the interface. The interface jump relations are re-derived accordingly. A novel rotational procedure is given to generate smooth local coordinate systems and make effective interpolation. Numerical examples demonstrate that the IIM Poisson solver and the Stokes solver achieve second-order accuracy. A 3D drop with insoluble surfactant under shear flow is investigated numerically by studying the influences of different physical parameters on the drop deformation.

scholarly journals ANALYSIS OF OPTICAL WAVEGUIDES WITH ARBITRARY INDEX PROFILE USING AN IMMERSED INTERFACE METHOD

2011 ◽  
Vol 22 (07) ◽  
pp. 687-710 ◽  
Author(s):  
THEODOROS P. HORIKIS
Keyword(s):  
Optical Waveguides ◽  
Eigenvalue Problems ◽  
Numerical Technique ◽  
Interface Problems ◽  
Index Profile ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Light Confinement ◽  
Bragg Fibers ◽  
Matrix Eigenvalue Problems

A numerical technique is described that can efficiently compute solutions of interface problems. These are problems with data, such as the coefficients of differential equations, discontinuous or even singular across one or more interfaces. A prime example of these problems are optical waveguides, and as such the scheme is applied to Maxwell's equations as they are formulated to describe light confinement in Bragg fibers. It is based on standard finite differences appropriately modified to take into account all possible discontinuities across the waveguide's interfaces due to the change of the refractive index. Second- and fourth-order schemes are described with additional adaptations to handle matrix eigenvalue problems, demanding geometries and defects.

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