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.

Axial Rupture in Underwater Pipelines

1990 ◽  
Vol 112 (2) ◽  
pp. 151-156 ◽  
Author(s):  
K. Crentsil ◽  
E. G. Hauptmann ◽  
P. G. Hill
Keyword(s):  
High Speed ◽  
Axial Strain ◽  
Crack Opening ◽  
Water Environment ◽  
Inertial Mass ◽  
Mass Effect ◽  
Small Scale ◽  
High Speed Photography ◽  
Surrounding Water ◽  
External Water

The propagation of axial cracks in underwater pipelines was investigated by means of small-scale pipe experiments. The purpose of the experiments was to determine the effect of external water environment on crack opening characteristics. The development of the axial rupture was recorded by high-speed photography; measurements were made of the internal depressurization transient and the axial strain field. The measured depressurization histories agreed with the predictions of a one-dimensional transient fluid flow code. Results presented for underwater and in-air tests show that the external water environment produces a slower crack and a smaller crack opening area. A steady-state energy balance analysis was performed to investigate the various energy dissipation mechanisms present during pipe rupture. This analysis confirmed that the added inertial mass effect of the surrounding water may account for the reduction in crack speed and opening area.

A Photographic Study of the Effect of an Air Bubble on the Growth and Collapse of a Vapor Bubble Near a Surface

1972 ◽  
Vol 94 (4) ◽  
pp. 933-940 ◽  
Author(s):  
R. H. Smith ◽  
R. B. Mesler
Keyword(s):  
Vapor Bubble ◽  
High Speed ◽  
Room Temperature ◽  
Solid Boundary ◽  
High Speed Photography ◽  
Air Bubbles ◽  
Gas Bubble ◽  
Air Bubble ◽  
Spark Gap ◽  
Damage Prevention

Interaction of an individual vapor bubble formed by a spark gap in water at room temperature with a neighboring air bubble, such as could have significance in cavitation, was investigated using high speed photography. Air bubbles were located both on and far from boundaries. An air bubble located on the solid boundary was able to protect the surface from damage. Two effects of the interaction which appeared to be important in the damage prevention were energy transfer from the vapor bubble to the gas bubble and repulsion of the vapor bubble by the gas bubble. Gas bubbles far from boundaries absorbed less energy and had less repulsive effect than those on solid boundaries.

scholarly journals Exploring the Optimal Design for and Experimentation on a Bowl-Based Mechanism for Transplanting Potted Strawberry Seedlings

2021 ◽  
Author(s):  
Yin Daqing ◽  
Yang Yuchao ◽  
Zhou Maile ◽  
Wei Mingxu ◽  
Wang Jinwu
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
High Speed Photography ◽  
Simulation Design ◽  
Three Dimensional Model ◽  
Three Dimensional Printing ◽  
New Device ◽  
Working Principle ◽  
Dimensional Printing ◽  
Actual Trajectory

Abstract To improve the mechanization of strawberry planting integration and the efficiency of fetching and transplanting seedlings, an integrated transplanting mechanism with protruding, fetching and planting is designed. This new device can realize rapid fetching and pushing bowl movements. The working principle of the slewing mechanism is analyzed, a kinematics model of the mechanism is established, and the optimization goal is established. Visual auxiliary analysis software is developed, optimized parameters are established, and the corresponding theoretical trajectory is provided. A three-dimensional model is established and a virtual simulation design analysis is performed to obtain a simulation trajectory. Three-dimensional printing technology is used to manufacture the test prototype, and the actual working trajectory of the test prototype is extracted using high-speed photography technology, which verifies the consistency of the actual trajectory with the theoretical and simulated trajectories. A prototype transplanting experiment is performed, showing that the success rate of seedling extraction is 91.2% and the rate of excellent planting is 82.8%, which meet the requirements for integrated strawberry harvesting, planting and transplanting and verify the correctness and feasibility of the mechanism design.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

Experimental study of hydrodynamic effects in the inverse water hydrocarbon emulsions flow in microchannels

2016 ◽  
Vol 11 (1) ◽  
pp. 30-37 ◽  
Author(s):  
A.A. Rakhimov ◽  
A.T. Akhmetov
Keyword(s):  
High Speed ◽  
Petroleum Industry ◽  
Chemical Compounds ◽  
High Viscosity ◽  
Blocking Effect ◽  
High Speed Photography ◽  
Simple Chemical ◽  
Reported Study ◽  
Dynamic Blocking ◽  
Hydrodynamic Effects

The paper presents results of hydrodynamic and rheological studies of the inverse water hydrocarbon emulsions. The success of the application of invert emulsions in the petroleum industry due, along with the high viscosity of the emulsion, greatly exceeding the viscosity of the carrier phase, the dynamic blocking effect, which consists in the fact that the rate of flow of emulsions in capillary structures and cracks falls with time to 3-4 orders, despite the permanent pressure drop. The reported study shows an increase in viscosity with increasing concentration or dispersion of emulsion. The increase in dispersion of w/o emulsion leads to an acceleration of the onset of dynamic blocking. The use of microfluidic devices, is made by soft photolithography, along with high-speed photography (10,000 frames/s), allowed us to see in the blocking condition the deformation of the microdroplets of water in inverse emulsion prepared from simple chemical compounds.

scholarly journals Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Lakshminath Kundanati ◽  
Prashant Das ◽  
Nicola M. Pugno
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Speed ◽  
Prey Capture ◽  
High Speed Photography ◽  
Sensory Organs ◽  
Dragonfly Nymph ◽  
Drag Forces ◽  
Predatory Insects ◽  
Dragonfly Nymphs

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

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