Single thermal plume in locally heated vertical soap films

Abstract

A vertical soap film is maintained by injection of a soap solution from the top. The film is then locally heated. Thermal plumes may be observed to rise in the film, depending on the magnitude of the heating and injected flows. The nearly two-dimensional nature of the system allows to visualize the motion of the plumes using an infrared camera. A model is proposed to describe the growth, emergence, and stationarity of the plumes in the film by taking into account both magnitudes of the heating ΔT and injected flow Q.

Rotation of melting ice disks due to melt fluid flow

“…Eventually, the water reaches locally the temperature of 4 • C. At this temperature the density of the water is the highest and the fluid sinks towards the bottom of the pool and generates a plume. The plume is similar to the thermal plume observed in soap films [7,8]. The plume induces the horizontal rotation of the fluid, i.e., a vertical vortex close to the bottom face of the ice disk.…”

Surface tension profiles in vertical soap films

“…When the solution comes out of the slot, it follows the edges of the pipe to reach the top of the film, which lies beneath the pipe. By doing so, it is possible to suppress the gravitational drainage and to build soap films which can last for hours [29], Choosing the flow rate carefully allows us to fix the thickness profile of the film in time. The thickness dependency versus the vertical coordinate H (see Fig.…”

“…We suppress the temporal evolution of the thickness profile of our films by feeding them using the setup sketched in Fig. 2 [27][28][29], A flow made of the soapy solution is injected at a constant flow rate Q from both sides in a slit pipe, the slot pointing upward. When the solution comes out of the slot, it follows the edges of the pipe to reach the top of the film, which lies beneath the pipe.…”

Mapping of the Marangoni effect in soap films using Young's double-slit experiment

“…Such an effect can also originate from a temperature gradient at the air/liquid interface and is sometimes called Rayleigh-Bénard convection [6,7] when it is linked to thermal convection. Whereas this effect is often invoked, quantitative measurements are scarce [8][9][10][11][12][13][14][15][16][17]. These measurements have been mainly performed, directly using either the naked eye, or with the help of a microscope, or using temperature sensitive markers, or probing the film thickness with interference techniques.…”

“…We could change the laser power of the heating violet beam, however, a higher laser power breaks the film and for a lower power, the film gradient is too low after 15 s drainage to make any relevant measurement. Previous experiments [11,16,[31][32][33][34] were performed under different conditions in order to measure high temperature gradients only. Devices associated with the deposition of a film on a metallic plate or to the free suspension of a film continuously supplied by a solution pump have been designed to increase artificially the film lifetime, which is not the case here.…”