Soap Films Research Articles

Symbolic Communication of Tourism Images in Soap Opera Televisions

Tourism in Bali is growing so rapidly that it continues to increase every year. The increasing number of foreign and domestic tourist arrivals leads to an increase in domestic services and promotions. Arief Yahya assessed that film had become a useful medium and contributed greatly to promoting Indonesian tourism. The aim of this research is to know how soap opera and film could be used as a means of promotion to know about Tourism in Bali and other state problems: (1) How Broadcasting as a mass communication activity functions as a medium of information, education, entertainment, health, control and social control; (2) How to carry out the function of soap opera and film as a means of promoting Tourism inBali;(3), How broadcasting also has economic and cultural functions. Theory and Method: Symbolic Theory and Method use perception and qualitative analysis which explore by watching the eat, pray, and love films and some soap operas whose shooting take place in Bali. They can serve as a reference for the industrial world to make films that can inspire audiences to come to the place or location of the film, and also a reference for tourists who would come to Bali.

Stationary soap films with vertical potentials

We classify cylindrical surfaces in the Euclidean space whose mean curvature is a nth-power of the distance to a reference plane. The generating curves of these surfaces, called n-elastic curves, have a variational characterization as critical points of a curvature energy generalizing the classical elastic energy. We give a full description of such curves obtaining, in some particular cases, closed curves including simple ones.

Soap Film Visualization of a 10 cm-Span Flapping Wing

Flapping wing micro-air-vehicles (FWMAVs) animate the small-space dexterous flight, hovering, and energy-saving characteristics of birds and insects, and are believed to have enlightenment for the development of bionic flight in the future. When designing FWMAVs, detailed unsteady aerodynamic information is required. Besides the computational fluid mechanics (CFD) technology study, the flow visualization is also needed to assist this research. This article innovatively used soap film visualization with high-speed photography to record two kinds of the 2D flow fields laterally and longitudinally, respectively, generated by a flapping wing of 10 cm span. Different from the qualitative comparison of soap film imaging with the conventional smoke tracing method, the subsequent processing of the soap film images was demonstrated. This work explains how to quantify the soap film imaging into lift and thrust forces, and the corresponding results are compared with the wind tunnel force measurement data preliminarily.

Source-driven vibration of a semi-rigid cantilever: Soap film experiments comparing incidence angles α = 0° and α = 180°

We present an experimental study of a source-driven vibrating semi-rigid cantilever. The source in this case was a cylinder of diameter D = 5.15 mm that generated vortices due to an upstream-uniform flow. The cylinder was placed ahead of a semi-rigid cantilever at inclination angle of either α = 0° or α = 180°; and the experiment took place in a soap film tunnel. The cantilevers had flexural rigidity EI = 2.7 × 10−8 Pa-m4 and length L = 7.5 mm. The Reynolds numbers were 10000 < Re < 14000 based on cylinder diameter.

Revisiting the “pearl string” in draining soap bubble film first witnessed by Sir James Dewar some 100 years ago: A note of analyses for the phenomena with related findings

The flow patterns of “pearl string” in draining bubble film as first witnessed by Sir James Dewar some 100 years ago were successfully reproduced by using chemically stable aqueous alkylbenzenesulfonate instead of alkylcarboylate used by Dewar as a soap. The concentration of aqueous surfactant used is as high as 5% by weight. The close-up pictures were taken by both still and video cameras at the magnification of around 10× with time for the draining flat bubble film prepared in vertically held rectangular frame made of a thin glass rod. The flow pattern of “threaded white beads” was found to appear at the shear boundary of black and gray flowing films. The successive and periodical deposition of tiny white particles to form “threaded pearls” is explained as the result of repeated nucleation of liquid crystalline phase as triggered by the stick-slip frictional sliding of black film at the boundary of the isotropic gray film and the subsequent growth of particles by isothermal condensation. The frequency of oscillational shear was found to be around 10 Hz for the shear velocity of 3 cm/s, which was approximated from the increased rate of black film area and the interval of beads in video images. The phenomena were explained as the deposition of liquid crystalline phase in the isotropic gray film the nucleation of which is triggered by the stick-slip frictional sliding motion of black film at the border of gray film. The whole process occurs in the course of gravity-induced syneresis of aqueous soap film.

Geometry of catenoidal soap film collapse induced by boundary deformation.

Experimental and theoretical work reported here on the collapse of catenoidal soap films of various viscosities reveal the existence of a robust geometric feature that appears not to have been analyzed previously; prior to the ultimate pinchoff event on the central axis, which is associated with the formation of a well-studied local double-cone structure folded back on itself, the film transiently consists of two acute-angle cones connected to the supporting rings, joined by a central quasicylindrical region. As the cylindrical region becomes unstable and pinches, the opening angle of those cones is found to be universal, independent of film viscosity. Moreover, that same opening angle at pinching is found when the transition occurs in a hemicatenoid bounded by a surface. The approach to the conical structure is found to obey classical Keller-Miksis scaling of the minimum radius as a function of time, down to very small but finite radii. While there is a large body of work on the detailed structure of the singularities associated with ultimate pinchoff events, these large-scale features have not been addressed. Here we study these geometrical aspects of film collapse by several distinct approaches, including a systematic analysis of the linear and weakly nonlinear dynamics in the neighborhood of the saddle node bifurcation leading to collapse, both within mean curvature flow and the physically realistic Euler flow associated with the incompressible dynamics of the surrounding air. These analyses are used to show how much of the geometry of collapsing catenoids is accurately captured by a few active modes triggered by boundary deformation. A separate analysis based on a mathematical sequence of shapes progressing from the critical catenoid towards the Goldschmidt solution is shown to predict accurately the cone angle at pinching. We suggest that the approach to the conical structures can be viewed as passage close to an unstable fixed point of conical similarity solutions. The overall analysis provides the basis for the systematic study of more complex problems of surface instabilities triggered by deformations of the supporting boundaries.

Soap film catastrophes

Earlier systematic experimental studies of bursting soap films by McEntee &amp; Mysels (J. Phys. Chem., vol. 73, 1969, pp. 3018–3028) revealed the existence of a precursor shock wave preceding the expanding hole in a punctured film, with a disturbed region of shrinking film material in between known as the ‘aureole’. In the present work we report and interpret new phenomena associated with the aureole – the formation of folds on the surface of soap films. In search of the theoretical explanation of the experimentally identified conditions under which the folds appear, we establish that they correspond to catastrophes of collapsing soap films.

Plateau's Problem as a Singular Limit of Capillarity Problems

Soap films at equilibrium are modeled, rather than as surfaces, as regions of small total volume through the introduction of a capillarity problem with a homotopic spanning condition. This point of view introduces a length scale in the classical Plateau's problem, which is in turn recovered in the vanishing volume limit. This approximation of area minimizing hypersurfaces leads to an energy based selection principle for Plateau's problem, points at physical features of soap films that are unaccessible by simply looking at minimal surfaces, and opens several challenging questions. © 2020 Wiley Periodicals LLC.

The wake of a transversely oscillating circular cylinder in a flowing soap film at low Reynolds number

An inclined gravity-driven soap film channel was used to study the wake patterns formed behind a transversely oscillating cylinder at Re=235±14. The natural frequency of vortex shedding from a stationary cylinder, fSt, was used to identify the oscillation frequencies of interest. The (dimensionless) frequency, f∗=f/fSt, and amplitude, A∗=A/D, of the cylinder’s motion was varied over a large portion of the fundamental synchronization region (i.e., for f∗≈1), and a ‘map’ of wake patterns was constructed in (f∗,A∗) space. Lock-on between the frequency of the cylinder’s motion and the dominant frequency of the resulting vortex wake was observed for a large range of this parameter space, predominantly manifested as synchronized ‘2S’ and ‘2P’ wake modes. Synchronized ‘P+S’, ‘2T’, and ‘transitional’ wakes were also found in smaller regions of parameter space. Unsynchronized ‘coalescing’ and ‘perturbed von Kármán’ wakes were observed as the oscillation frequency became sufficiently different from fSt. The wake patterns and vortex formation processes found in this study, particularly the 2P mode wakes, bear a strong resemblance to previous three-dimensional experimental results, despite the physical constraint from the soap film that limits three-dimensional effects in the wake.

Evolution of shock-accelerated double-layer gas cylinder

Developments of the shock-accelerated concentric double-layer gas cylinder with an air cylinder embedded into an SF6 cylinder have been experimentally investigated for the first time. The double-layer gas cylinder is created by the soap film technique. Effects of the inner cylinder on the evolution of the outer one are highlighted by changing the radius ratio, i.e., a ratio of the inner radius to the outer one. The flow features show that the two cylinders evolve independently at the early stage, whereas they couple together at the late stage. The presence of the inner cylinder changes the behavior of shock movements, and a vortex pair instead of an outward jet is generated at the downstream interface. The scale of the vortex pair is proportional to the initial radius ratio. The rarefaction waves generated from the upstream interface of the inner cylinder accelerate the upstream interface of the outer cylinder earlier than the single-layer SF6 cylinder. Depending on the radius ratio, the acceleration induced by the rarefaction wave impact either prolongs or shortens the linear phase of the upstream interface movement. The waves' effect results in the failure of the nonlinear model in predicting the upstream interface movement. For the outer cylinder, its movements in both the streamwise and spanwise directions are promoted by the inner one. For the inner cylinder, its movements in the streamwise and spanwise directions are, respectively, inhibited and promoted by the outer one. As the radius ratio increases, the effect of promotion or prohibition is stronger.

On flowing soap films as experimental models of 2D Navier–Stokes flows

On flowing soap films as experimental models of 2D Navier–Stokes flows

Calibration of gas flow meters using choked flow and an evacuated vessel

The measurement of gas flow rates is of great importance in a wide range of modern technologies. This paper introduces a simple, yet accurate technique for in-house calibration of gas FMs (mass and volumetric) even under harsh environmental conditions such as encountered during field measurement campaigns. The method requires only readily available, low cost components: a vessel of known volume, an air pump, a pressure sensor and a metal plate orifice or a needle valve to act as a CO. The unique property of choked flow in the CO is used here for flow calibration. In the method presented here a vessel is evacuated to below the critical pressure (<0.53 of upstream pressure) and then allowed to refill with ambient air (or some other process gas) under so-called choked flow conditions through the CO. The method presented here leverages that the flow rate upstream of the CO is not only constant but readily determined from (a) the known V VESS, (b) the measured time rate of change of the absolute pressure in the vessel and (c) the ideal gas law. This calculated flow rate can be used for calibration of FMs. The accuracy of the method depends only on the accuracy of the pressure measurement, the timer and the value of the V VESS. The flow rate computed in this way is found to be in excellent agreement (typically 1% difference) with the flow rate measured by a soap film FM (Gilibrator). As expected from theory this method is found to work for all kinds of CFRs (here: various types of metal plate orifices and needle valves were tested), gas types (here: air, Argon, and CO2) and upstream pressures (here: between 650 hPa and 1400 hPa). The accuracy of this technique (∼1%) is as good as that of standard volume displacement methods (e.g. soap film FMs) (typically 1% difference), the standard of laboratory-based flow calibrators, but less expensive and more suitable for harsh environments.

Soap film on two noncircular frames

The classical Plateau problem of finding minimal surfaces supported by two noncircular coaxial rings is studied theoretically and experimentally. Using a fluid dynamics analogy, we generalize the classical catenoid solution for a film on circular rings to the general cases of noncircular rings. Some examples of analytical solutions for elliptical, polygonal, and ovoidal rings are presented. The shapes of a tubular film and a film separated by a lamella at the wrist are obtained in an analytical form. The stability of these films is analyzed and compared with the classical catenoid. The data on critical parameters of all minimal surfaces are collected in the tables that can be used in practical applications. The theory is experimentally validated using soap films on elliptical identical frames. Moreover, the shapes of soap films on two different elliptical frames demonstrate a new feature: a flat separating lamella lying parallel to the rings was never observed in experiments. All lamellae appeared deformed suggesting the existence of a new family of minimal surfaces which does not exist in the case of frames of the same sizes.

Mathematics of Soap Films

Mathematics of Soap Films

A new setup for giant soap films characterization.

Artists, using empirical knowledge, manage to generate and play with giant soap films and bubbles. Until now, scientific studies of soap films generated at a controlled velocity and without any feeding from the top, studied films of a few square centimeters. The present work aims to present a new setup to generate and characterize giant soap films (2m [Formula: see text] 0.7m). Our setup is enclosed in a humidity-controlled box of 2.2m high, 1m long, and 0.75m large. Soap films are entrained by a fishing line withdrawn out of a bubbling solution at various velocities. We measure the maximum height of the generated soap films, as well as their lifetime, thanks to automatic detection. This is allowed by light-sensitive resistors collecting the light reflected on the soap films and ensures robust statistical measurements. In the meantime, thickness measurements are performed with a UV-VIS-spectrometer, allowing us to map the soap film's thickness over time.

Studies of Interactions between Water Droplet and Soap Film

In this paper, it explored the interactions between water droplet and soap film. Three types of interactions: merging (droplet and film merges after interaction), bouncing (droplet bounces off the film) and passing (droplet pass through the film) are mainly examined, and how the mass and impact velocity of water droplet will affect the film deformation are studied. After understanding the importance of surface tension and Weber number, both simulation and experiment are used to verify the theory and to interpret the phenomena of droplet-film interactions.

High-speed visualization of soap films bursting dynamics

High-speed (2873 fps) visualization of soap film bursting dynamics has been performed by means of equipment available to a high school laboratory. This paper presents the geometry of the experiment and description of the analysis method of the video frames. We carried out the experiments on the bursting of vertical plane soap films using a circular frame with single central and non-central puncture of the film by a needle. The studies were also performed with simultaneous puncture of the film by two needles. Similar research of the films bursting was done using a non-circular frame in the form of a nonconvex hexagon. In all cases, the rupture line has the shape of a circle. For the first time, the displacement of the circular burst center upwards is recorded and explained. Flapping oscillations of the rupture line border at its movement are confirmed. The oscillating character of the rupture line movement is recorded and explained. In addition, we detected formation of the liquid bridge and its destruction at the interaction of two circular bursts with double puncture of the film.

Local 𝐶^{1,𝛽}-regularity at the boundary of two dimensional sliding almost minimal sets in ℝ³

In this paper, we will give a C 1 , β C^{1,\beta } -regularity result on the boundary for two dimensional sliding almost minimal sets in R 3 \mathbb {R}^3 . This effect may apply to the regularity of the soap films at the boundary, and may also lead to the existence of a solution to the Plateau problem with sliding boundary conditions proposed by Guy David in the case that the boundary is a 2-dimensional smooth submanifold.

Multiscale Sample Entropy of Two-Dimensional Decaying Turbulence.

Multiscale sample entropy analysis has been developed to quantify the complexity and the predictability of a time series, originally developed for physiological time series. In this study, the analysis was applied to the turbulence data. We measured time series data for the velocity fluctuation, in either the longitudinal or transverse direction, of turbulent soap film flows at various locations. The research was to assess the feasibility of using the entropy analysis to qualitatively characterize turbulence, without using any conventional energetic analysis of turbulence. The study showed that the application of the entropy analysis to the turbulence data is promising. From the analysis, we successfully captured two important features of the turbulent soap films. It is indicated that the turbulence is anisotropic from the directional disparity. In addition, we observed that the most unpredictable time scale increases with the downstream distance, which is an indication of the decaying turbulence.

Collapsing and the convex hull property in a soap film capillarity model

Soap films hanging from a wire frame are studied in the framework of capillarity theory. Minimizers in the corresponding variational problem are known to consist of positive volume regions with boundaries of constant mean curvature/pressure, possibly connected by “collapsed” minimal surfaces. We prove here that collapsing only occurs if the mean curvature/pressure of the bulky regions is negative, and that, when this last property holds, the whole soap film lies in the convex hull of its boundary wire frame.