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.

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.

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.

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