Ascent Of Bubbles Research Articles

Experimental observations of the rate of ascent of bubbles in lubricating oils

Experimental observations of the rate of ascent of bubbles in lubricating oils

Retardation of the ascent of gas bubbles by surface-active solutes in nonaqueous solutions

Hydrodynamical theory predicts that the rate of rise of a spherical bubble in a liquid is affected by the presence of a surface-active solute, which retards the rate, by a factor of up to two-thirds, as more solute is adsorbed and the bubble interface is thereby rendered increasingly more rigid. The retardation of the rate of rise of a bubble as a function of concentration of solute therefore reflects the transition from a fluid to a rigid interface. With weakly surface-active solutes in nonaqueous solvents the course of this transition may be readily observed. Examples of this behavior in such solutions are reported. The data reported permit the computation of the surface-tension difference between the top and bottom of an ascending bubble of fixed size throughout the transition region of flow behavior, between a completely fluid and a completely rigid interface.

Über die dynamik der Blasenbildung beim begasen von Flüssigkeiten unter druck

The author describes experiments for the treatment of water with helium, argon and nitrogen at pressures of 1 to 80 atm abs. The greater kinetic energy possessed by gases at elevated pressures causes considerable deformation of the bubbles and more rapid disintegration of the gas stream into bubbles than in gassing at normal pressure. Striking discontinuities are observed, viz., a sudden rise in bubble frequency occurs at increased gas rates. Photographs show the bubble shapes and bubble ascent in various ranges of pressure, varying between introduction of the gas as single bubbles and as a coherent stream at high rates of throughput.

The velocity of ascent of bubbles in glass with an unsteady temperature schedule

The velocity of ascent of bubbles in glass with an unsteady temperature schedule

THE EROSION OF CUMULUS TOWERS

Abstract A differential equation is formulated for the rate of rise of isolated buoyant elements in the atmosphere, based in part on analogy with the work of Davies and Taylor (1950) who studied the ascent of air bubbles in liquid. The equation involves a drag force which is proportional to the ascent velocity squared and which depends upon a linear dimension of the buoyant element, such as the radius of curvature of its upper surface. To eliminate this dimension from the differential equation, a law for the erosion, or rate of decrease in size of these buoyant air bubbles has been proposed. The basic assumptions are that the elements erode sufficiently slowly so that the flow around them is nearly the same as if they were in equilibrium, and that they retain their shape. From combination of the erosion law and the equation of motion, an erosion parameter, E, is derived, which to the extent that the laws are valid should be constant for all isolated cloudy bubbles, regardless of air mass or location. The ...

Bubble theory of penetrative convection

AbstractThe process of convection is described in terms of a unit or proton of convection ‐ the bubble. A rising bubble of warm air sheds its outer skin steadily into a disturbed wake until it becomes exhausted completely or spreads out at a stable layer. The wake is a region where the ascent of further bubbles is favoured. The wakes of small bubbles close to the ground are aggregated into larger bubbles, which are more dilute, up to a level where they begin to penetrate hitherto undisturbed air, and then they waste away as they ascend further.The air above a bubble is lifted (and cooled) as the bubble approaches and then drains down the outside, the air close to the bubble being mixed into the wake. The wake of a clear bubble is buoyant but that of a cloudy bubble may sink if it is sufficiently chilled by dilution with surrounding clear air.The drag on a bubble is estimated from observations on rising cumulus towers, and a linear relation between buoyancy and limiting velocity is proposed. From this the horizontal velocity of the bubble relative to the surrounding air is deduced to be about the same as the vertical velocity when it ascends through strong shear.A bubble is a compact stable configuration for a rising element. Near the ground the heat is transported by small bubbles, which are less efficient, and therefore require a greater lapse rate, than the larger ones which can operate higher up. The process of aggregation is again renewed within large clouds so that the bubbles found at the top may be more dilute than if they had ascended directly from the base. Clouds growing in a shearing current will grow into the shear.