EXPERIMENTAL AND NUMERICAL ANALYSIS OF CHAOTIC ADVECTION AS AN EFFICIENT APPROACH TO MAXIMIZE HOMOGENEOUS LAMINAR MIXING IN A BATCH MIXER

It is a difficult task to achieve an efficient mixing inside a microchannel since the flow is characterized by low Reynolds number (Re). Recently, the serpentine laminating micromixer (SLM) was reported to achieve an efficient chaotic mixing by introducing ‘F’-shape mixing units successively in two layers such that two chaotic mixing mechanisms, namely splitting/recombination and chaotic advection, enhance the mixing performance in combination. The present study describes an improved serpentine laminating micromixer (ISLM) with a novel redesign of the ‘F’-shape mixing unit. Reduced cross-sectional area at the recombination region of ISLM locally enhances advection effect which helps better vertical lamination, resulting in improved mixing performance. Flow characteristics and mixing performances of SLM and ISLM are investigated numerically and verified experimentally. Numerical analysis system is developed based on a finite element method and a colored particle tracking method, while mixing entropy is adopted as a quantitative mixing measure. Numerical analysis result confirms enhanced vertical lamination performance and consequently improved mixing performance of ISLM. For experimental verification, SLM and ISLM were fabricated by polydimethylsiloxane (PDMS) casting against SU-8 patterned masters. Mixing performance is observed by normalized red color intensity change of phenolphthalein along the downchannel. Flow characteristics of SLM and ISLM are investigated by tracing the red interface of two streams via optical micrograph. The normalized mixing intensity behavior confirms improved mixing performance of ISLM, which is consistent with numerical analysis result.

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Topological Chaos by Pseudo-Anosov Map in Cavity Laminar Mixing

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4026634 ◽

2015 ◽

Vol 10 (2) ◽

Cited By ~ 2

Author(s):

Baiping Xu ◽

Lih-Sheng Turng ◽

Huiwen Yu ◽

Meigui Wang

Keyword(s):

Power Index ◽

Chaotic Advection ◽

Passive Tracer ◽

Complete Spatial Randomness ◽

Tracer Particles ◽

Laminar Mixing ◽

Short Period ◽

Flow Domain ◽

Interface Prediction ◽

Volume Method

A numerical investigation was carried out to study the mixing behavior of Stokes flows in a rectangular cavity stirred by three square rods. The square loops of the rods move in such a way that a pseudo-Anosov map can be built in the flow domain in the augmented phase space. The finite volume method was used, and the flow domain was meshed by staggered grids with the periodic boundary conditions of the rod motion being imposed by the mesh supposition technique. Fluid particle tracking was carried out by a fourth-order Runge–Kutta scheme. Tracer stretches from different initial positions were used to evaluate interface prediction by a pseudo-Anosov map. The colored short period Poincaré section was obtained to reveal the size of the domain in which the pseudo-Anosov map was in effect. Dye advection patterns were used to analyze chaotic advection of passive tracer particles using statistical concepts such as “variances” and “complete spatial randomness.” For the fluid in the core region of the cavity, tracer interface stretches experienced exponential increases and had the same power index as that predicted by the pseudo-Anosov map matrix.

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Experimental/Numerical Analysis of Chaotic Advection in a Three-dimensional Cavity Flow

International Polymer Processing ◽

10.3139/217.0125 ◽

2006 ◽

Vol 21 (4) ◽

pp. 412-420 ◽

Cited By ~ 7

Author(s):

P. D. Anderson ◽

D. Ternet ◽

G. W. M. Peters ◽

H. E. H. Meijer

Keyword(s):

Numerical Analysis ◽

Three Dimensional ◽

Cavity Flow ◽

Chaotic Advection

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ANALYSIS OF POSITION AND ROTATION DIRECTION OF DOUBLE STIRRER ON CHAOTIC ADVECTION BEHAVIOR

EUREKA Physics and Engineering ◽

10.21303/2461-4262.2021.001707 ◽

2021 ◽

pp. 78-86

Author(s):

Sugeng Hadi Susilo ◽

Asrori Asrori

Keyword(s):

Chaotic Behavior ◽

Video Camera ◽

Chaotic Advection ◽

Reverse Direction ◽

Mixing Efficiency ◽

Viscous Liquids ◽

Rotation Direction ◽

Laminar Mixing ◽

The Difference ◽

Index Value

Turbulent mixing can damage the material molecules because of turbulence. Whereas laminar mixing raises a problem when mixing is carried out on viscous liquids. The mixing mechanism using chaotic flow affects the mixing quality. The aim of the experiment was to determine the position and direction of the double stirrer chaotic mixer. The installation of a chaotic mixer uses a cylindrical tub and two different mixers consisting of a primary mixer (Pp) and a secondary mixer (Ps). Periodically rotate the container and stirrer. The center of the vessel and primary mixer are placed at the same coordinates. For ε=4 cm (Pp to Ps distance), there are three experiments, namely: vessel rotation and directional stirrer (P2S-a), vessel rotation and opposite stirrer (P2B-a), and vessel rotation, both primary and secondary stirrers are directional variations. (P2V-a). Eccentricity 7 cm, there are also three treatments as above: one direction (P2S-b), reverse direction (P2B-b), and variation of direction (P2V-b). The video camera recordings are processed digitally. Qualitative data show a pattern of behavior during mixing. Meanwhile, quantitative data is used to determine the level of mixing effectiveness. The results showed that the direction of rotation of the two cylinders had no effect on the effectiveness of chaotic mixing. Based on the number of initial droplets of dye, the treatment that experienced the fastest chaos was P2B-b, at n=2 and r=3.5303. The difference in the number of color droplets does not affect chaotic behavior. The highest mixing efficiency was generated by the lowest P2V-b mixing index value of 0.94. Simultaneously, the direction between the mixer and the container will provide maximum mixing efficiency. Isolated mixing areas (island) and areas of poor mixing occur because of one-way rotation and low eccentricity

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