A numerical study of single air bubble formation comparison between in viscous liquid and in water

Introduction: Hip resurfacing remains a valid option in young male patients. The creation of the optimum cement mantle aids fixation of the femoral component. If the cement mantle is too thick the prosthesis can remain proud leading to early failure or if it penetrates too far into the femoral head, it may cause osteonecrosis. Method: 18 of 96 femoral heads collected from patients undergoing total hip arthroplasty were matched for their surface porosity. They were randomly allocated into 2 different cementing groups. Group 1 had the traditional bolus of cement technique, while group 2 had a modified cementing technique (swirl) where the inside of the femoral component was lined with an even layer of low viscosity cement. Results: The traditional bolus technique had significantly greater cement mantle thickness in 3 of 4 zones of penetration ( p = 0.002), greater and larger air bubble formation (6 of 9 in bolus technique vs. 1 in 9 in swirl technique, p = 0.05) and more incomplete cement mantles compared with the swirl technique. There was no relationship to femoral head porosity. Conclusion: The swirl technique should be used to cement the femoral component in hip resurfacing. Long-term clinical studies would conform if this translates into increased survivorship of the femoral component.

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

ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, Volume 2 ◽

10.1115/icnmm2011-58238 ◽

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.

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Air Bubble Injection Into a Liquid Stream in a Minichannel

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73082 ◽

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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Numerical Study of Bubble Growth on a Micro-Finned Surface

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-10016 ◽

2011 ◽

Author(s):

Woorim Lee ◽

Gihun Son

Keyword(s):

Heat Transfer ◽

Bubble Growth ◽

Bubble Dynamics ◽

Numerical Study ◽

Removal Rate ◽

Bubble Formation ◽

Experimental Studies ◽

Nucleate Boiling ◽

Finned Surface ◽

Fin Spacing

Bubble growth on a micro-finned surface, which can be used in enhancing boiling heat transfer, is numerically investigated by solving the conservation equations of mass, momentum, and energy. The bubble deformation or the liquid-vapor interface is determined by the sharp-interface level-set method, which is modified to include the effect of phase change and to treat the contact angle and the evaporative heat flux from the liquid microlayer on an immersed solid surface of a microfin. The numerical method is applied to clarify bubble growth and heat transfer characteristics on a surface including fin and cavity during nucleate boiling which have not been provided from the previous experimental studies. The effects of single fin, fin-cavity distance, and fin-fin spacing on the bubble dynamics are investigated. The micro-fin is found to affect the activation of cavity. The fin-cavity configuration is found to determine the bubble formation in a cavity. The vapor removal rate is also observed to significantly depend on the fin-fin spacing.

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Theoretical Modeling of Thermal Transients in a PCM Substrate During Drop Impact

ASME 2019 Heat Transfer Summer Conference ◽

10.1115/ht2019-3648 ◽

2019 ◽

Author(s):

Andrew Quon ◽

Abdul Ahad Khan ◽

Navdeep Singh Dhillon

Keyword(s):

Heat Transfer ◽

Numerical Study ◽

Bubble Formation ◽

Transient Behavior ◽

Drop Impact ◽

Aircraft Icing ◽

Liquid Drops ◽

Thermal Transients ◽

Solidification Problem ◽

Impact Experiments

Abstract The physics of transient behavior of liquid drops impacting hot and cold surfaces is of significance in many different applications such as spray cooling, condensation and aircraft icing, and analogous to the process of bubble formation and departure in boiling. The resulting local thermal transients in these processes are primarily dictated by passive parameters such as substrate and liquid thermal properties and flow conditions. We are exploring the use of a surface-embedded phase change material (PCM) to actively manipulate these thermal transients as a means to enhance overall heat transfer performance. The thermal effect of the embedded PCM can be parametrically studied using controlled drop impact experiments. In this work, we perform an analytical and numerical study to model the effect of a liquid drop impacting a hot PCM-embedded substrate. By solving an analytical heat transfer solidification problem, we study the effect of PCM properties and PCM initial temperature on the thermal transients encountered during drop impact. Further, we validate the numerical analysis by showing agreement with experimental results.

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