Surface tension effects in the zero gravity inflow of a drop into a fluid

2000 ◽  
Vol 15 (2) ◽  
pp. 331-334 ◽  
Author(s):  
S. Residori ◽  
E. Pampaloni ◽  
P.K. Buah-Bassuah ◽  
F.T. Arecchi
Keyword(s):  
Surface Tension ◽  
Zero Gravity

The mechanism of bubble detachment from a wall at zero and negative gravity

1976 ◽  
Vol 77 (2) ◽  
pp. 313-320 ◽  
Author(s):  
G. Malcotsis
Keyword(s):  
Surface Tension ◽  
Vertical Wall ◽  
Two Dimensions ◽  
Gravity Force ◽  
Zero Gravity ◽  
Air Bubbles ◽  
Subcooled Boiling ◽  
Vapour Bubble ◽  
Approximate Representation ◽  
Bubble Detachment

An experiment has been carried out in which air bubbles were caused to grow isothermally at a vertical wall between two closely spaced horizontal plates. The experiment gives an approximate representation in two dimensions for the growth of a vapour bubble at a wall under some conditions of subcooled boiling in zero gravity. Although the effect of gravity was virtually eliminated in the experiment, it was found that a bubble could still detach itself from the wall, apparently owing to the effects of surface tension and inertia.Also, bubbles were seen to detach from a wall despite the presence of a slight gravity force directed to oppose such detachment.

Effects of Gravity, Shear and Surface Tension in Internal Condensing Flows: Results From Direct Computational Simulations

2004 ◽  
Vol 126 (5) ◽  
pp. 676-686 ◽  
Author(s):  
Q. Liang ◽  
X. Wang ◽  
A. Narain
Keyword(s):  
Surface Tension ◽  
Normal Gravity ◽  
Numerical Solutions ◽  
Vertical Channel ◽  
Film Condensation ◽  
Vapor Flow ◽  
Zero Gravity ◽  
Pressure Drops ◽  
Condensing Flows ◽  
Internal Condensing Flows

The paper presents accurate numerical solutions of the full two-dimensional governing equations for steady and unsteady laminar/laminar internal condensing flows. The results relate to issues of better design and integration of condenser-sections in thermal management systems (looped heat pipes, etc.). The flow geometry, in normal or zero gravity, is chosen to be the inside of a channel with film condensation on one of the walls. In normal gravity, film condensation is on the bottom wall of a tilted (from vertical to horizontal) channel. It is found that it is important to know whether the exit conditions are constrained or unconstrained because nearly incompressible vapor flows occur only for exit conditions that are unconstrained. For the incompressible vapor flow situations, a method for computationally obtaining the requisite exit condition and associated stable steady/quasi-steady solutions is given here and the resulting solutions are shown to be in good agreement with some relevant experimental data for horizontal channels. These solutions are shown to be sensitive to the frequency and amplitude of the various Fourier components that represent the ever-present and minuscule transverse vibrations (standing waves) of the condensing surface. Compared to a vertical channel in normal gravity, shear driven zero gravity cases have much larger pressure drops, much slower wave speeds, much larger noise sensitive wave amplitudes that are controlled by surface tension, and narrower flow regime boundaries within which vapor flow can be considered incompressible. It is shown that significant enhancement in wave-energy and/or heat-transfer rates, if desired, are possible by designing the condensing surface noise to be in resonance with the intrinsic waves.

scholarly journals Dynamics of poles in two-dimensional hydrodynamics with free surface: new constants of motion

2019 ◽  
Vol 874 ◽  
pp. 891-925 ◽  
Author(s):  
A. I. Dyachenko ◽  
S. A. Dyachenko ◽  
P. M. Lushnikov ◽  
V. E. Zakharov
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Half Plane ◽  
Second Order ◽  
Zero Gravity ◽  
Two Dimensional ◽  
Branch Points ◽  
Integrals Of Motion ◽  
Complex Half Plane ◽  
Constants Of Motion

We address the problem of the potential motion of an ideal incompressible fluid with a free surface and infinite depth in a two-dimensional geometry. We admit the presence of gravity forces and surface tension. A time-dependent conformal mapping $z(w,t)$ of the lower complex half-plane of the variable $w$ into the area filled with fluid is performed with the real line of $w$ mapped into the free fluid’s surface. We study the dynamics of singularities of both $z(w,t)$ and the complex fluid potential $\unicode[STIX]{x1D6F1}(w,t)$ in the upper complex half-plane of $w$. We show the existence of solutions with an arbitrary finite number $N$ of complex poles in $z_{w}(w,t)$ and $\unicode[STIX]{x1D6F1}_{w}(w,t)$ which are the derivatives of $z(w,t)$ and $\unicode[STIX]{x1D6F1}(w,t)$ over $w$. We stress that these solutions are not purely rational because they generally have branch points at other positions of the upper complex half-plane. The orders of poles can be arbitrary for zero surface tension while all orders are even for non-zero surface tension. We find that the residues of $z_{w}(w,t)$ at these $N$ points are new, previously unknown, constants of motion, see also Zakharov & Dyachenko (2012, authors’ unpublished observations, arXiv:1206.2046) for the preliminary results. All these constants of motion commute with each other in the sense of the underlying Hamiltonian dynamics. In the absence of both gravity and surface tension, the residues of $\unicode[STIX]{x1D6F1}_{w}(w,t)$ are also the constants of motion while non-zero gravity $g$ ensures a trivial linear dependence of these residues on time. A Laurent series expansion of both $z_{w}(w,t)$ and $\unicode[STIX]{x1D6F1}_{w}(w,t)$ at each poles position reveals the existence of additional integrals of motion for poles of the second order. If all poles are simple then the number of independent real integrals of motion is $4N$ for zero gravity and $4N-1$ for non-zero gravity. For the second-order poles we found $6N$ motion integrals for zero gravity and $6N-1$ for non-zero gravity. We suggest that the existence of these non-trivial constants of motion provides an argument in support of the conjecture of complete integrability of free surface hydrodynamics in deep water. Analytical results are solidly supported by high precision numerics.

The Effect of the Marangoni Flow on the Film Condensation

2009 ◽  
Author(s):  
Baohong Peng ◽  
Li Yang ◽  
Juan Wen
Keyword(s):  
Surface Tension ◽  
Reynolds Number ◽  
Marangoni Effect ◽  
Film Condensation ◽  
Zero Gravity ◽  
Vapor Film ◽  
Marangoni Flow ◽  
Shearing Force ◽  
Gravity Condition ◽  
Average Ratio

The objective of this paper is to quantify the effect of Marangoni flow on the vapor film condensation and analyzed the effect of the gravity, the shearing force at the gas-liquid interface and the Marangoni strength caused by the surface tension on the Nusselt number. The results show that the effect of the gravity is very clear to the thickness of the film. Marangoni effect can not be ignored at zero gravity condition. The effect of the vapor Reynolds number (Rev0) at the zero-gravity conditions on the film is bigger than that at the gravity conditions. The average ratio of the film thickness (δ¯) is 6.5% at the gravity conditions and 21.5% at zero-gravity conditions when the Rev0 changes from 8000 to 15000.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

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