Generation and Transport of Bubbles in a Microfluidic Device

2008 ◽  
Author(s):  
Renqiang Xiong ◽  
Jacob N. Chung
Keyword(s):  
Silicon Wafer ◽  
Microfluidic Device ◽  
High Speed ◽  
Micro Channel ◽  
Bubble Generation ◽  
Air Bubble ◽  
Micro Scale ◽  
Bubble Transport

In this paper we used high speed recording to characterize segmented micro-scale air bubble generation in a T-junction and bubble transport in a serpentine micro-channel fabricated in a standard silicon wafer.

Captured air bubble (CAB) high-speed over-water vehicle report

1964 ◽  
Author(s):  
A. FORD
Keyword(s):  
High Speed ◽  
Air Bubble

scholarly journals Dry-ED milling of micro-scale contours with high-speed rotating tungsten tube electrodes

Procedia CIRP ◽  
2020 ◽  
Vol 95 ◽  
pp. 533-538
Author(s):  
E. Uhlmann ◽  
I. Perfilov ◽  
S. Yabroudi ◽  
R. Mevert ◽  
M. Polte
Keyword(s):  
High Speed ◽  
Micro Scale

scholarly journals Interfacial Tension Sensor for Low Dosage Surfactant Detection

2021 ◽  
Vol 5 (1) ◽  
pp. 9
Author(s):  
Piotr Pawliszak ◽  
Bronwyn H. Bradshaw-Hajek ◽  
Christopher Greet ◽  
William Skinner ◽  
David A. Beattie ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Microfluidic Device ◽  
Profile Analysis ◽  
Simple Method ◽  
Bubble Generation ◽  
Flotation Process ◽  
Line Measurement ◽  
Tension Sensor ◽  
Low Dosage

Currently there are no available methods for in-line measurement of gas-liquid interfacial tension during the flotation process. Microfluidic devices have the potential to be deployed in such settings to allow for a rapid in-line determination of the interfacial tension, and hence provide information on frother concentration. This paper presents the development of a simple method for interfacial tension determination based on a microfluidic device with a flow-focusing geometry. The bubble generation frequency in such a microfluidic device is correlated with the concentration of two flotation frothers (characterized by very different adsorption kinetic behavior). The results are compared with the equilibrium interfacial tension values determined using classical profile analysis tensiometry.

Thermal Wake of a Single Rising Air Bubble in a Large Body of Stagnant Liquid

2007 ◽  
Author(s):  
Majid Molki ◽  
Bahman Abbasi
Keyword(s):  
High Speed ◽  
Thermal Field ◽  
Large Body ◽  
Heat Transfer Process ◽  
Computational Effort ◽  
Temperature Fields ◽  
High Speed Photography ◽  
Three Dimensional Model ◽  
Surrounding Water ◽  
Air Bubble

A computational effort was undertaken to study the thermal field behind a slowly rising solitary air bubble. Starting from rest, the bubble moves upward in water due to buoyancy force in the gravitational field and induces both internal and external motion. The bubble, being colder than the surrounding water, is heated by water. The upward motion deforms the shape of the bubble and generates a convective heat transfer process. Variation of temperature at the gas-liquid interface causes a local variation of surface tension. Although the problems of this type have been generally treated by the axisymmetric assumption, the present work employs a three-dimensional model that captures the azimuthal variation of flow parameters. High-speed photography was employed to visualize the bubble evolution from the onset until the bubble reached a certain velocity. The computations were performed using the finite-volume and Volume of Fluid (VOF) techniques. The shape and evolution of the bubble as predicted by the computations are compared with those captured on the high-speed photographs. The computations revealed details of the pressure and temperature fields inside and outside the bubble. They also indicated the thermal field in the wake region behind the bubble.

Mixing Characteristics of a Two-Phase Flow (Gas-Liquid) Microchannel Mixer

2011 ◽  
Author(s):  
Tarek Abdel-Salam ◽  
Srikanth Pidugu
Keyword(s):  
Reynolds Number ◽  
Two Phase Flow ◽  
Bubble Formation ◽  
Width Ratio ◽  
Phase Flow ◽  
Two Phase ◽  
Bubble Generation ◽  
Air Bubble ◽  
And Performance ◽  
Actual Shape

Multiphase phase flows occur in many engineering and bio-medical applications. Bubble formation in microchannels can be beneficial or harmful depending upon their influence on the operation and performance of microfludic devices. Potential uses of bubble generation found in many applications such as microreactors, micropump, and micromixers. In the present work the flow and mixing process in a passive microchannel mixer were numerically investigated. Effects of velocity, and inlet width ratio (Dgas/Dliquid) on the two phase flow were studied. Numerical results are obtained for 2-dimensional and 3-dimesional cases with a finite volume CFD code and using structured grids. Different liquid-gas Reynolds number ratios (Reliquid/Regas) were used ranging from 4 to 42. In addition, three values of the inlet width ratio (Dgas/Dliquid) were used. Results for the 3-D cases capture the actual shape of the air bubble with the thin film between the bubble and the walls. Also, increasing Reliquid increases the rate of the development of the air bubble. The bubble length increases with the increase of Dgas/Dliquid. For the same values of Re, the rate of growth of the bubble increases with the increase of Dgas/Dliquid. Finally, a correlation is provided to predict the length of the bubble with liquid-gas Reynolds number ratio (Reliquid/Regas) and tube width.

Air Bubble Entrainment, Breakup, and Interplay in Vertical Plunging Jets

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Numa Bertola ◽  
Hang Wang ◽  
Hubert Chanson
Keyword(s):  
High Speed ◽  
Point Explosion ◽  
Air Bubble ◽  
Bubble Breakup ◽  
Jet Impact ◽  
Bubble Entrainment ◽  
Bubble Interaction ◽  
Onset Velocity ◽  
Air Cavities ◽  
Interaction Behaviors

The entrainment, breakup, and interplay of air bubbles were observed in a vertical, two-dimensional supported jet at low impact velocities. Ultra-high-speed movies were analyzed both qualitatively and quantitatively. The onset velocity of bubble entrainment was between 0.9 and 1.1 m/s. Most bubbles were entrained as detached bubbles from elongated air cavities at the impingement point. Explosion, stretching, and dejection mechanisms were observed for individual bubble breakup, and the bubble interaction behaviors encompassed bubble rebound, “kiss-and-go,” coalescence and breakup induced by approaching bubble(s). The effects of jet impact velocity on the bubble behaviors were investigated for impact velocities from 1.0 to 1.36 m/s, in the presence of a shear flow environment.

Impact Tests in an Air-Water Mixture

2017 ◽  
Author(s):  
Aboulghit El Malki Alaoui
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Optical Probe ◽  
Test Machine ◽  
Water Mixture ◽  
Air Bubble ◽  
Impact Tests ◽  
Void Fractions ◽  
Shock Test Machine ◽  
The Impact

Experimental impact tests were performed using a shock machine and aerated water by means of an air-bubble generator. High speed shock test machine allows carrying out tests of impact on water (slamming). This machine permits to stabilise velocity with a maximal error equal to 10% during slamming tests. The air volume fraction in the bubble was measured by optical probe technique. The present work is aimed at quantifying the effects of the aeration on the hydrodynamic loads and pressures during the entry of a rigid body at constant speed in an air-water mixture. The impact tests were conducted with a rigid pyramid for an impact velocity equal to 15 m.s−1 and for two average void fractions, 0,46% and 0,84%. The reduction of the impact force and pressure due to aeration has been confirmed by these experiments.

Flow over a stepped chute with and without macro-roughness elements

2004 ◽  
Vol 31 (5) ◽  
pp. 880-891 ◽  
Author(s):  
Mehmet Ali Kökpinar
Keyword(s):  
Water Flow ◽  
High Speed ◽  
Length Distribution ◽  
Air Entrainment ◽  
Air Concentration ◽  
Bubble Frequency ◽  
Two Phase ◽  
Air Bubble ◽  
Roughness Elements ◽  
Stepped Chute

High-speed two-phase flows over a 30° stepped flume were experimentally investigated using macro-roughness elements. The roughness elements included combinations of steps and horizontal strips. Local values of air concentration, air bubble frequency, and mean chord lengths were measured by a fiber-optical instrumentation system in the air–water flow region. The range of unit discharge of water was varied from 0.06 to 0.20 m2/s. Three step configurations were studied: (i) without macro-roughness elements, (ii) with macro-roughness elements on each step, and (iii) with macro-roughness elements on each second step (AMR configuration). The results were compared in terms of onset flow conditions and internal air–water flow parameters such as local air concentration, mean air bubble chord length distribution, and air bubble frequency in the skimming flow regime. It was observed that the AMR configuration produced the maximum free-surface aeration among the other configurations. This alternative step geometry has potential for less cavitation damage than conventional step geometry because of the greater air entrainment.Key words: stepped chute, air-entrainment, air-water flow properties, macro-roughness elements, skimming flow.

Algorithm Analysis of Gas Bubble Generation in a Microfluidic Device

2019 ◽  
Vol 13 (2) ◽  
pp. 133-141
Author(s):  
Jang Ho Ha ◽  
Hirak Mazumdar ◽  
Tae Hyeon Kim ◽  
Jong Min Lee ◽  
Jeong-Geol Na ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Algorithm Analysis ◽  
Gas Bubble ◽  
Bubble Generation

Air Bubble Injection Into a Liquid Stream in a Minichannel

2013 ◽  
Author(s):  
Randy Samaroo ◽  
Masahiro Kawaji
Keyword(s):  
High Speed ◽  
Liquid Velocity ◽  
Bubble Formation ◽  
Video Camera ◽  
Velocity Profiles ◽  
Bubble Behavior ◽  
Particle Image Velocimetry Technique ◽  
Air Bubble ◽  
Cfd Models ◽  
Laminar And Turbulent Flow

Air bubble injection experiments have been performed to obtain a better understanding and detailed data on bubble behavior and liquid velocity profiles to be used for validation of 3-D Interface Tracking Models and CFD models. Two test sections used were vertical rectangular minichannels with a width and gap of 20 mm × 5.1 mm and 20 mm × 1.9 mm, respectively. Subcooled water at near atmospheric pressure flowed upward under laminar and turbulent flow conditions accompanied by air bubbles injected from a small hole on one of the vertical walls. The experiments yielded data on bubble formation and departure, and interactions with laminar or turbulent water flow. Instantaneous and ensemble-average liquid velocity profiles have been obtained using a Particle Image Velocimetry technique and a high speed video camera.

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