Vapour bubble collapse in isothermal and non-isothermal liquids

2008 ◽  
Vol 601 ◽  
pp. 253-279 ◽  
Author(s):  
BINZE YANG ◽  
ANDREA PROSPERETTI
Keyword(s):  
Surface Area ◽  
Axial Symmetry ◽  
Dynamic Stress ◽  
Fluid Dynamic ◽  
Spherical Model ◽  
Added Mass ◽  
Bubble Collapse ◽  
Translational Velocity ◽  
Vapour Bubble ◽  
Subcooled Liquid

The motion of a vapour bubble in a subcooled liquid is studied numerically assuming axial symmetry but allowing the surface to deform under the action of the fluid dynamic stress. The flattening of the bubble in the plane orthogonal to the translational velocity increases the added mass and slows it down, while, at the same time, the decreasing volume tends to increase the velocity. The deformation of the interface also increases the surface area exposed to the incoming cooler liquid. The competition among these opposing processes is subtle and the details of the condensation cannot be captured by simpler models, two of which are considered. In spite of these differences, the estimate of the total collapse time given by a spherical model is close to that of the deforming bubble model for the cases studied. In addition to an isothermal liquid, some examples in which the bubble encounters warmer and colder liquid regions are shown.

scholarly journals Impact effects due to hot vapour bubble collapse in subcooled liquid

2020 ◽  
Vol 1652 ◽  
pp. 012019
Author(s):  
T C Le ◽  
V I Melikhov ◽  
O I Melikhov ◽  
S E Yakush
Keyword(s):  
Bubble Collapse ◽  
Vapour Bubble ◽  
Subcooled Liquid

scholarly journals Hydrodynamic Forces Exerting on an Oscillating Cylinder under Translational Motion in Water Covered by Compressed Ice

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 822
Author(s):  
Yury Stepanyants ◽  
Izolda Sturova
Keyword(s):  
Lift Force ◽  
Wave Motion ◽  
Translational Motion ◽  
Added Mass ◽  
Hydrodynamic Forces ◽  
Wave Resistance ◽  
Translational Velocity ◽  
Damping Coefficients ◽  
Incompressible Ideal Fluid ◽  
Theoretical Results

This paper presents the calculation of the hydrodynamic forces exerted on an oscillating circular cylinder when it moves perpendicular to its axis in infinitely deep water covered by compressed ice. The cylinder can oscillate both horizontally and vertically in the course of its translational motion. In the linear approximation, a solution is found for the steady wave motion generated by the cylinder within the hydrodynamic set of equations for the incompressible ideal fluid. It is shown that, depending on the rate of ice compression, both normal and anomalous dispersion can occur in the system. In the latter case, the group velocity can be opposite to the phase velocity in a certain range of wavenumbers. The dependences of the hydrodynamic loads exerted on the cylinder (the added mass, damping coefficients, wave resistance and lift force) on the translational velocity and frequency of oscillation were studied. It was shown that there is a possibility of the appearance of negative values for the damping coefficients at the relatively big cylinder velocity; then, the wave resistance decreases with the increase in cylinder velocity. The theoretical results were underpinned by the numerical calculations for the real parameters of ice and cylinder motion.

Spherical vapour bubble collapse

1974 ◽  
Vol 29 (2) ◽  
pp. 363-371 ◽  
Author(s):  
S.J. Board ◽  
A.D. Kimpton
Keyword(s):  
Bubble Collapse ◽  
Vapour Bubble

scholarly journals The impact of fluid-dynamic stress in stirred tank bioreactors on the synthesis of cellulases by Trichoderma reesei at the intracellular and extracellular levels

2021 ◽  
Vol 232 ◽  
pp. 116353
Author(s):  
Tamiris Roque ◽  
Jérôme Delettre ◽  
Nicolas Hardy ◽  
Alvin W. Nienow ◽  
Frédéric Augier ◽  
...  
Keyword(s):  
Trichoderma Reesei ◽  
Dynamic Stress ◽  
Fluid Dynamic ◽  
Stirred Tank ◽  
The Impact

Bubble Growth and Collapse in Liquid Nitrogen

1968 ◽  
Vol 90 (1) ◽  
pp. 22-26 ◽  
Author(s):  
H. C. Hewitt ◽  
J. D. Parker
Keyword(s):  
Experimental Data ◽  
Liquid Nitrogen ◽  
Bubble Growth ◽  
Theoretical Work ◽  
Nitrogen Pressure ◽  
Superheated Liquid ◽  
Bubble Collapse ◽  
Vapor Bubbles ◽  
Subcooled Liquid ◽  
Nitrogen Bubble

Experimental data on bubble growth in superheated liquid nitrogen, bubble collapse in subcooled liquid nitrogen, and bubble growth with decreasing liquid nitrogen pressure are compared to the theoretical solutions obtained for noncryogens. Vapor bubbles in liquid nitrogen were found to behave quite similarly to vapor bubbles in noncryogens. This paper provides experimental data in two areas where additional theoretical work is needed: Bubble collapse in subcooled liquid, and bubble growth with decreasing pressure.

scholarly journals Comparative computed flow dynamic analysis of different optimization techniques in left main either provisional or culotte stenting

2017 ◽  
Vol 5 (4) ◽  
pp. 205-212 ◽  
Author(s):  
Gianluca Rigatelli ◽  
Fabio Dell’Avvocata ◽  
Marco Zuin ◽  
Sara Giatti ◽  
Khanh Duong ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Surface Area ◽  
Fluid Dynamic ◽  
Optimization Techniques ◽  
The Other ◽  
Left Main ◽  
Flow Dynamic ◽  
Physiological Profile ◽  
Provisional Stenting ◽  
The Impact

Abstract Background and Objectives Provisional and culotte are the most commonly used techniques in left main (LM) stenting. The impact of different post-dilation techniques on fluid dynamic of LM bifurcation has not been yet investigated. The aim of this study is to evaluate, by means of computational fluid dynamic analysis (CFD), the impact of different post-dilation techniques including proximal optimization technique (POT), kissing balloon (KB), POT-Side-POT and POT–KB-POT, 2-steps Kissing (2SK) and Snuggle Kissing balloon (SKB) on flow dynamic profile after LM provisional or culotte stenting. Methods We considered an LM-LCA-LCX bifurcation reconstructed after reviewing 100 consecutive patients (mean age 71.4 ± 9.3 years, 49 males) with LM distal disease. The diameters of LAD and LCX were modelled according to the Finnet’s law as following: LM 4.5 mm, LAD 3.5 mm, LCX 2.75 mm, with bifurcation angle set up at 55°. Xience third-generation stent (Abbot Inc., USA) was reconstructed and virtually implanted in provisional/cross-over and culotte fashion. POT, KB, POT-side-POT, POT-KB-POT, 2SK and SKB were virtually applied and analyzed in terms of the wall shear stress (WSS). Results Analyzing the provisional stenting, the 2SK and KB techniques had a statistically significant lower impact on the WSS at the carina, while POT seemed to obtain a neutral effect. In the wall opposite to the carina, the more physiological profile has been obtained by KB and POT with higher WSS value and smaller surface area of the lower WSS. In culotte stenting, at the carina, POT-KB-POT and 2SK had a very physiological profile; while at the wall opposite to the carina, 2SK and POT–KB-POT decreased significantly the surface area of the lower WSS compared to the other techniques. Conclusion From the fluid dynamic point of view in LM provisional stenting, POT, 2SK and KB showed a similar beneficial impact on the bifurcation rheology, while in LM culotte stenting, POT-KB-POT and 2SK performed slightly better than the other techniques, probably reflecting a better strut apposition.

EXTREME DRAG FORCES AND THE SURVIVAL OF WIND- AND WATER-SWEPT ORGANISMS

1994 ◽  
Vol 194 (1) ◽  
pp. 97-115 ◽  
Author(s):  
M Denny
Keyword(s):  
Probability Distribution ◽  
Turbulent Flow ◽  
Flat Plate ◽  
Dynamic Stress ◽  
Fluid Dynamic ◽  
Drag Forces ◽  
Mainstream Flow ◽  
Terrestrial Habitats ◽  
The Mean ◽  
Benthic Animals

A stationary organism exposed to steady turbulent flow is subjected to a drag force that fluctuates about a mean, and when the drag on the organism is characterized, it is traditionally this mean force that is cited. Important information is lost, however, when the fluctuations in drag are ignored. This is particularly true when extreme drag forces are relevant; for instance, when predicting the survival of benthic animals on wave-swept shores and in torrential streams, or of plants in windblown terrestrial habitats. This study reports on the probability distribution of drag fluctuations for five objects: a flat plate, large and small cylinders, a sphere and a limpet shell. Distributions vary substantially among different objects exposed to the same mainstream flow; the sphere and limpet exhibit larger fluctuations than the plate and cylinders. The distribution of extremes in drag is used to predict the likelihood that an organism will be dislodged. For organisms in which the applied fluid-dynamic stress is near the mean breaking stress (e.g. some corals, trees and mussels), calculations made using the extreme drag can yield a probability of dislodgment substantially higher than that calculated using the average.

Flow Field Characteristic Analysis and Structural Optimization of a Centrifugal Gas-Liquid Separator

2007 ◽  
Author(s):  
Lixin Zhao ◽  
Baojun Zhu ◽  
Yong Zhang
Keyword(s):  
Flow Field ◽  
Structural Optimization ◽  
Axial Symmetry ◽  
Optimization Design ◽  
Phase Distribution ◽  
Fluid Dynamic ◽  
Gas Content ◽  
Characteristic Analysis ◽  
Bottom Part ◽  
Liquid Separator

Based on computational fluid dynamic (CFD) method, the simulation of a normal vertical-vessel type centrifugal gas-liquid separator was carried out, by using Gambit and FLUENT soft packs. It is found that the axial symmetry of the flow field is bad, the gas-content near underflow outlet is higher, which indicates the separating effect of the separator is not satisfied. Through structural optimization, including changing the underflow outlet from side to bottom, designing double inlets, reducing the vessel diameter, extending the overflow tube to the bottom of inlet tube, changing the bottom part of the separator from cylindrical to conical structure, etc., so as to improve the axial symmetry of the separator flow field, including gas phase distribution, then to enhance its separation effect. CFD analysis result of velocity distribution is in accordance with Laser Doppler Anemometer (LDA) result qualitatively. All of these will provide some reference on structural optimization. It is concluded that CFD aided optimization design is very helpful for fluid machinery design, which can guide experimental work and decrease the experimental time and cost to a great extent.

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