A Micromixer Using the Chaos of Secondary Flow: Rotation Effect of Channel on the Chaos of Secondary Flow

Abstract

The micromixer, which has a rotor with a curved channel, is studied experimentally. The secondary flow in a curved channel of rectangular cross-section is investigated using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) methods. Two walls of the channel (the inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction of the exit of the channel. The non-dimensional channel curvature a R   is taken to be about 0.1, where 2a is the width of the channel, R the curvature radius of the channel. Other non-dimensional parameters concerned are the Dean number 1 2 De Re  , the Reynolds number Re h qd   , where q is the mean flow velocity in the channel axis direction, ν the kinematic viscosity, d h the hydraulic diameter of the channel, and the Taylor number     1 2 2 Tr 2 2 a   , wh   ere Ω is the angular velocity of the rotor. Photographs of the flow in a cross-section at 180˚ downstream from the curved channel entrance are taken by changing the flux   De constant rotational speed   Tr the channel walls. It is found that good mixing performance is obtained in the case of at a of De  for that case secondary flows show chaotic behaviors. And then we have confirmed the occurrence of reversal of the mean axial flow. 0.1 Tr and the micromixer of this type is important in a practical use two walls of the channel rotate.

A Micromixer Using the Taylor-Dean Flow: Effects of Aspect Ratio and Inflow Condition on the Mixing

“…Figure 5 shows experimental results of LIF under the Conditions I and II at the cross-section of 180˚ downstream from the curved channel entrance. They are results of De ≤ 0.1 Tr with the condition in which mixing was promoted as in the experiment of Condition I [7]. The right and top sides of each picture are moving walls that moves in the perpendicular direction to the sheet of the picture, while the left and bottom sides are stationary walls.…”

“…The experimental setup and procedure are the same as Refs. [7] [10]. A diagram of the experimental setup is shown in Figure 1.…”

“…Then we proposed a micromixer making use of chaos of the secondary flow, specifically, a micromixer in which the secondary flow becomes chaotic through a curved channel where two walls of the channel rotate [7]. This flow is a kind of Taylor-Dean flows [8].…”

The Physics and Manipulation of Dean Vortices in Single- and Two-Phase Flow in Curved Microchannels: A Review

“…Geometrical manipulation is a passive method that utilizes the microchannel's geometric properties to control the flow [36,37]. For example, channels with grooves form stream-wise vortices which can be employed for mixing enhancement [38][39][40][41]. T-junction channels generate monodisperse droplets which are a method of cell and particle encapsulation [42,43].…”

A Micromixer Using the Taylor-Dean Flow: Effect of Inflow Conditions on the Mixing

“…We then proposed a micromixer making use of chaos of the secondary flow, specifically, a micromixer in which the secondary flow becomes chaotic through a curved channel where two walls of the channel rotate [6]. This flow is a kind of Taylor-Dean flows [7].…”