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The Laplace pressure is the pressure difference between the inside and the outside of a curved surface that forms the boundary between two fluid regions. [1] The pressure difference is caused by the surface tension of the interface between liquid and gas, or between two immiscible liquids. The Laplace pressure is determined from the Young ...
This pressure difference can be calculated from Laplace's pressure equation, Δ P = 2 γ R {\displaystyle \Delta P={\frac {2\gamma }{R}}} . For a soap bubble, there exists two boundary surfaces, internal and external, and therefore two contributions to the excess pressure and Laplace's formula doubles to
In physics, the Young–Laplace equation (/ l ə ˈ p l ɑː s /) is an algebraic equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although use of the latter is only applicable if assuming that the wall is very thin.
Therefore the pressure step/stability method is the most recommended one for research and development applications. Additionally, the pressure step/stability measuring principle allows measuring the true First Bubble Point (FBP), in opposition to the pressure scan method, which only permits calculation the FBP at the selected flow rates.
This basic stability requirement, and similar ones for other conjugate pairs of variables, is violated in analytic models of first order phase transitions. The most famous case is the van der Waals equation , [ 2 ] [ 3 ] p = R T / ( v − b ) − a / v 2 {\displaystyle p=RT/(v-b)-a/v^{2}} where a , b , R {\displaystyle a,b,R} are dimensional ...
The change in vapor pressure can be attributed to changes in the Laplace pressure. When the Laplace pressure rises in a droplet, the droplet tends to evaporate more easily. When applying the Kelvin equation, two cases must be distinguished: A drop of liquid in its own vapor will result in a convex liquid surface, and a bubble of vapor in a ...
In the following years Vogel [18] [19] extended the theory. He examined the case of axisymmetric capillary bridges with constant volumes and the stability changes correspond to turning points. The recent development of bifurcation theory proved that exchange of stability between turning points and branch points is a general phenomenon. [20] [21]
This figure represents the evolution of the Rayleigh–Taylor instability from small wavelength perturbations at the interface (a) which grow into the ubiquitous mushroom shaped spikes (fluid structures of heavy into light fluid) and bubbles (fluid structures of light into heavy fluid) (b) and these fluid structures interact due to bubble merging and competition (c) eventually developing into ...