V. V. Guzanov

Specific features of a transition from the regular two-dimensional to three-dimensional waves on falling liquid films

The transition from a regular two-dimensional to three-dimensional (3D) flow in vertically falling liquid films has been experimentally studied. This transition is accompanied by a significant redistribution of liquid in the lateral direction. Characteristic shapes of 3D structures developing in the course of the transition are described.

Formation of rivulets in isothermal liquid film flow during transition to a three-dimensional wave regime

We present the results of an experimental investigation of the transition from a two-dimensional to three-dimensional (3D) flow in a liquid film flowing down a vertical plate of large dimensions. It is established that this transition is accompanied by the formation of rivulets. At large distances from the initial region, the wave regime can be almost completely suppressed in inter-rivulet regions.

Instability of a two-phase flow in a rectangular channel

A two-phase (liquid-gas) flow in a short horizontal slit channel of a rectangular cross section with a height of 440 μm has been experimentally studied using a fluorescent method, which allowed the flow pattern to be monitored and its quantitative characteristics to be measured. It is established that two-phase flow regimes in this channel substantially differ from the classical regimes of flow in extended channels of large cross section. It is demonstrated that the formation of various two-phase flow regimes and the transitions between them in short narrow rectangular slits are determined by instability of the liquid-gas flow at the side-walls of the channel.

Experimental study of the evolution of solitary three-dimensional waves on the surface of a heated liquid film

Results of an experimental investigation of the features of evolution of a solitary three-dimensional (3D) wave on the surface of a vertically falling liquid film heated by a constant heat flux are presented. It is established that the wave weakly influences the film surface temperature. The interaction of a 3D wave with thermocapillary rivulet structures on the falling film surface results in that the wave is pulled toward the center of a rivulet.

Characteristics of solitary three-dimensional waves on vertically falling liquid films

Results of systematic investigations of the characteristics of stationary solitary three-dimensional (3D) waves in vertically falling films of liquids with various physical properties are presented. Experimentally determined characteristics of the stationary 3D waves are compared to theoretically predicted values. A domain of film flow regimes is established in which the theory well agrees with experiment.

Flow structure in three-dimensional waves on a vertically falling liquid film

We have simultaneously measured the velocity vector and film thickness fields in three-dimensional (3D) waves formed upon the decay of regular 2D waves on a liquid film flowing down a vertical plate. Velocity fields at various distances from the plate surface in various regions of a 3D wave are constructed. It is shown that the liquid flow in the wave has a complex structure with regions of backflow and spanwise streams, which mainly occur under the main crest of the wave.

Rivulet dynamics at isothermal film flow

Averaged fields of thickness of an isothermal vertically flowing liquid film, obtained by the laserinduced fluorescence method, have been analyzed. The chosen minimum averaging time interval, at which the wave motion is completely averaged, allows one to observe rivulet dynamics in a transverse direction. It is found that short-lived rivulets, which are chains of no less than five to eight waves with similar transverse coordinates, are dominant structures on the film surface at Reynolds number Re > 50.