scholarly journals Modeling of an AC-Electro-Osmosis Based Microfluidic Mixer

2017 ◽  
Author(s):  
H. Dilara Uslu ◽  
Çetin Canpolat ◽  
Barbaros Çetin
Keyword(s):  
Electric Fields ◽  
Comsol Multiphysics ◽  
Governing Equations ◽  
Ac Electroosmosis ◽  
Flow Rates ◽  
Microfluidic Mixer ◽  
Mixing Performance ◽  
Electro Osmosis ◽  
Micro Mixer ◽  
Electro Osmotic Flow

The purpose of this study is presenting an active micro-mixer, which is based on AC electro-osmotic flow driven on 3D micro wires. In order to solve governing equations of AC electroosmosis, a commercial software COMSOL Multiphysics® is implemented. Different wire configurations with various imposed electric fields and flow rates are tested for evaluating mixing efficiencies. The analyses show that mixing performance is significantly improved by number of the wires as well as wire orientation. It is also revealed that the degree of mixing can also be controlled by the tuning of the applied voltage for a given flow rate.

Induced-charge electro-osmotic flow around cylinders with various orientations

2016 ◽  
Vol 231 (21) ◽  
pp. 4057-4066 ◽  
Author(s):  
Cetin Canpolat
Keyword(s):  
Electric Fields ◽  
Double Layers ◽  
Cylinder Surface ◽  
Osmotic Flow ◽  
Ac Electric Fields ◽  
Velocity Magnitude ◽  
Electro Osmosis ◽  
Microparticle Image Velocimetry ◽  
Induced Charge ◽  
Electro Osmotic Flow

Induced-charge electro-osmosis around multiple gold-coated stainless steel rods under various AC electric fields is investigated using the techniques of microparticle image velocimetry and numerical simulation. In this study, the results of interactions between induced electric double layers of two identical conductive cylinders on surrounding fluid are presented. The induced-charge electro-osmosis flow around multiple rods in touch and with one cylinder diameter gap reveals quadrupolar flow structures with four vortices. The induced-charge electro-osmotic flow structure and velocity magnitude also depend on the cylinder geometry and orientation. It is seen that four small vortices develop in the close region of cylinder surface for multiple rods with gap, while the other four large vortices are surrounding them. The distributions of vorticity patterns also strongly depend on cylinder orientation in the close region of cylinder surface.

Simulation-based assessment of coupled frequency response of magneto-electro-elastic auxetic multifunctional structures subjected to various electromagnetic circuits

2021 ◽  
pp. 146442072110219
Author(s):  
Vinyas Mahesh ◽  
Vishwas Mahesh ◽  
Dineshkumar Harursampath ◽  
Ahmed E Abouelregal
Keyword(s):  
Electric Fields ◽  
Solid Mechanics ◽  
Natural Frequencies ◽  
Comsol Multiphysics ◽  
Simulation Based ◽  
Electric And Magnetic Fields ◽  
Auxetic Structures ◽  
Triangular Elements ◽  
Benchmark Solutions ◽  
Free Vibration Response

This article deals with the modeling of magneto-electro-elastic auxetic structures and developing a methodology in COMSOL Multiphysics® to assess the free vibration response of such structures when subjected to various electromagnetic circuit conditions. The triple energy interaction between elastic, magnetic, and electric fields are established in the COMSOL Multiphysics® using structural mechanics and electromagnetic modules. The multiphase magneto-electro-elastic material with different percentages of piezoelectric and piezomagnetic phases are used as the material. In the solid mechanics module, the piezoelectric and piezomagnetic materials were created in stress-charge and stress-magnetization forms, respectively. The electric and magnetic fields are defined in COMSOL Multiphysics® through electromagnetic equations. Further, the customized controlled meshing constituted of free tetrahedral and triangular elements is adapted to trade-off between the accuracy and the computational expenses. The eigenvalue analysis is performed to obtain the natural frequencies of the MEE re-entrant auxetic structures. Also, the efficiency of smart auxetic structures over conventional honeycomb structures is presented throughout the manuscript. In addition, the discrepancy in the natural frequencies of the structures considering coupled and uncoupled state is also illustrated. It is believed that the modeling procedure and its outcomes serve as benchmark solutions for further design and analysis of smart auxetic magneto-electro-elastic structures.

scholarly journals Effect of magnetic field on nanofluid free convection in Conical Partially Annular Space

2020 ◽  
Vol 330 ◽  
pp. 01005
Author(s):  
Abderrahmane AISSA ◽  
Mohamed Amine MEDEBBER ◽  
Khaled Al-Farhany ◽  
Mohammed SAHNOUN ◽  
Ali Khaleel Kareem ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Boussinesq Approximation ◽  
Simulation Software ◽  
Comsol Multiphysics ◽  
Governing Equations ◽  
Element Analysis ◽  
Vertical Side ◽  
Side Walls

Natural convection of a magneto hydrodynamic nanofluid in a porous cavity in the presence of a magnetic field is investigated. The two vertical side walls are held isothermally at temperatures Th and Tc, while the horizontal walls of the outer cone are adiabatic. The governing equations obtained with the Boussinesq approximation are solved using Comsol Multiphysics finite element analysis and simulation software. Impact of Rayleigh number (Ra), Hartmann number (Ha) and nanofluid volume fraction (ϕ) are depicted. Results indicated that temperature gradient increases considerably with enhance of Ra and ϕ but it reduces with increases of Ha.

Fabrication of Tunable Silk Materials Through Microfluidic Mixers

2016 ◽  
Author(s):  
Joseph R. Nalbach ◽  
Dave Jao ◽  
Douglas G. Petro ◽  
Kyle M. Raudenbush ◽  
Shibbir Ahmad ◽  
...  
Keyword(s):  
Soft Lithography ◽  
Mixing Processes ◽  
Microfluidic Mixing ◽  
Microfluidic Mixer ◽  
Continuous Mixing ◽  
Mixing Performance ◽  
3D Printed ◽  
Distribution Uniformity ◽  
Mixing Patterns ◽  
Microfluidic Mixers

A common method to precisely control the material properties is to evenly distribute functional nanomaterials within the substrate. For example, it is possible to mix a silk solution and nanomaterials together to form one tuned silk sample. However, the nanomaterials are likely to aggregate in the traditional manual mixing processes. Here we report a pilot study of utilizing specific microfluidic mixing designs to achieve a uniform nanomaterial distribution with minimal aggregation. Mixing patterns are created based on classic designs and then validated by experimental results. The devices are fabricated on polydimethylsiloxane (PDMS) using 3D printed molds and soft lithography for rapid replication. The initial mixing performance is validated through the mixing of two solutions with colored dyes. The microfluidic mixer designs are further analyzed by creating silk-based film samples. The cured film is inspected with scanning electron microscopy (SEM) to reveal the distribution uniformity of the dye particles within the silk material matrix. Our preliminary results show that the microfluidic mixing produces uniform distribution of dye particles. Because the microfluidic device can be used as a continuous mixing tool, we believe it will provide a powerful platform for better preparation of silk materials. By using different types of nanomaterials such as graphite (demonstrated in this study), graphene, carbon nanotubes, and magnetic nanoparticles, the resulting silk samples can be fine-tuned with desired electrical, mechanical, and magnetic properties.

scholarly journals Numerical and Experimental Study of Cross-Sectional Effects on the Mixing Performance of the Spiral Microfluidics

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1470
Author(s):  
Omid Rouhi ◽  
Sajad Razavi Bazaz ◽  
Hamid Niazmand ◽  
Fateme Mirakhorli ◽  
Sima Mas-hafi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Numerical Study ◽  
Large Angle ◽  
Element Model ◽  
Channel Length ◽  
Cross Sectional ◽  
Flow Rates ◽  
Lab On Chip ◽  
Mixing Performance ◽  
Dean Flow

Mixing at the microscale is of great importance for various applications ranging from biological and chemical synthesis to drug delivery. Among the numerous types of micromixers that have been developed, planar passive spiral micromixers have gained considerable interest due to their ease of fabrication and integration into complex miniaturized systems. However, less attention has been paid to non-planar spiral micromixers with various cross-sections and the effects of these cross-sections on the total performance of the micromixer. Here, mixing performance in a spiral micromixer with different channel cross-sections is evaluated experimentally and numerically in the Re range of 0.001 to 50. The accuracy of the 3D-finite element model was first verified at different flow rates by tracking the mixing index across the loops, which were directly proportional to the spiral radius and were hence also proportional to the Dean flow. It is shown that higher flow rates induce stronger vortices compared to lower flow rates; thus, fewer loops are required for efficient mixing. The numerical study revealed that a large-angle outward trapezoidal cross-section provides the highest mixing performance, reaching efficiencies of up to 95%. Moreover, the velocity/vorticity along the channel length was analyzed and discussed to evaluate channel mixing performance. A relatively low pressure drop (<130 kPa) makes these passive spiral micromixers ideal candidates for various lab-on-chip applications.

A micromixer with consistent mixing performance for a wide range of flow rates

2014 ◽  
Vol 36 (3) ◽  
pp. 405-412 ◽  
Author(s):  
Robert Goovaerts ◽  
Tom Van Assche ◽  
Marc Sonck ◽  
Joeri Denayer ◽  
Gert Desmet
Keyword(s):  
Flow Rates ◽  
Mixing Performance ◽  
Wide Range

The effect of slip on electro-osmotic flow of a second-grade fluid between two plates with Caputo–Fabrizio time fractional derivatives

2019 ◽  
Vol 97 (5) ◽  
pp. 509-516 ◽  
Author(s):  
Aziz Ullah Awan ◽  
Muhammad Danial Hisham ◽  
Nauman Raza
Keyword(s):  
Slip Flow ◽  
Second Grade ◽  
Parallel Plates ◽  
Second Grade Fluid ◽  
Thin Channel ◽  
Electro Osmosis ◽  
The Laplace Transform ◽  
Grade Fluid ◽  
Electro Osmotic Flow ◽  
Fractional Parameter

This work aims to probe the slip flow of second-grade fluid. The impetus of the flow is taken to be the electro-osmosis and the pressure gradient. The flow is considered to be in a thin channel-like passage formed by two parallel plates. The potential difference existing between the surface of the solid and fluid is taken to be non-symmetric. The governing equations are formed for the second-grade fluid with the Caputo–Fabrizio fractional derivative. The Laplace transform is used for transforming the problem into space parameters after introducing the dimensionless variables. Instead of developing an analytical expression for inverse Laplacian, the numerical Stehfest algorithm is used. A tabular comparison of the obtained results by two different methods (Stehfest and Tzou) is given and the conformity of the two ensures the validity of our obtained results. The results are also pictured in terms of graphs and carry the information of the slip flow effect. Furthermore, the effect of the fractional parameter on velocity has also been tabulated using different values of fractional parameter.

Characterization of the Mixing Performance of an Innovative Hepatic Sinusoids-Based Microreactor Using Villermaux-Dushman Protocol

2020 ◽  
Vol 1008 ◽  
pp. 28-32
Author(s):  
Mahmoud Abdelghany Shouman ◽  
Ahmed Hassan El-Shazly ◽  
Marwa Farouk El-Kady ◽  
Mohamed Nabil Sabry
Keyword(s):  
Single Layer ◽  
Industrial Applications ◽  
Low Flow ◽  
Reactor Performance ◽  
Test Reaction ◽  
Chemical Test ◽  
Flow Rates ◽  
Mixing Performance ◽  
Mixing Quality ◽  
Microreactor Technology

Microreactor technology has drawn attention in many industrial applications, especially those that requires the use of low flow rates whereas the flow is considered to be stratified. At such low flow rates, the reactor performance is usually down especially if mass transfer occurs mainly by diffusion. In the present work, the mixing performance of a novel hepatic sinusoids-based microreactor has been investigated using Villermaux–Dushman protocol. The protocol is an iodide/iodate chemical test reaction that relies on testing the absorbance of the product at 352 nm as an indication of the formation of triiodide. The investigation is carried out at low flow rates ranges from 0.5 to 3 ml/min. The novel microreactor has proven to give satisfactory performance and is easy to be fabricated as it consists of a single layer. The absorbance of light ranges between 0.29 to 0.48 resulting on the creation of limited amount of triiodide ions. It is also noticed that the mixing performance of the reactor is nearly the same over the whole studied range of flow rate. The mixing quality is also determined using another system containing 200 ppm congo red aqueous solution and pure distilled water. About 94% to 96% mixing quality is achieved.

Two-Color Micro PIV Measurements of Particle and Fluid Motion in AC Electrokinetics

Materials ◽  
2003 ◽  
Author(s):  
Dazhi Wang ◽  
Carl Meinhart ◽  
Marin Sigurdson
Keyword(s):  
Electric Fields ◽  
Fluorescent Dyes ◽  
Fluid Velocity ◽  
A Priori ◽  
Fluid Motion ◽  
Ac Electroosmosis ◽  
Ac Electrokinetics ◽  
Piv Measurements ◽  
Drag Forces ◽  
Micro Piv

Two-Color μ-PIV is developed and used to uniquely determine the fluid velocity based on the micron-resolution Particle Image Velocimetry (μ-PIV) technique [1–3]. The fluid velocity field was obtained by measuring the motion of two different sizes particles, 0.7 and 1.0 μm. The different sizes of particles contain different fluorescent dyes, allowing them to be distinguished using fluorescent filter cubes. By comparing the velocity fields from the two different size particles, the underlying fluid motion can be uniquely determined, without a priori knowledge of the electrical properties of the particles, or the electrical field. The test section is formed by two wedge-shaped electrodes sandwiched between two glass wafers. In the presence of nonuniform ac electric fields, the particles experience dielectrophoretic (DEP) forces due to polarization and drag forces due to viscous interaction with the suspending medium, and the fluid motion is induced by the electrothermal effect and/or ac electroosmosis. The micro-PIV measurements are used to determine quantitatively the physical characteristics of the AC electrokinetic effects.

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