Horizontal convective flow from a line heat source located at the liquid–gas interface in presence of surface film

Abstract

Development of the convective flow from a line heat source located at the liquid surface is studied for the case when thermocapillary convection is inhibited by the surface film. Surface film is formed by small amounts of surfactants present in non-deionized (distilled or natural) water. It imposes a no-slip boundary condition for velocity at the surface and determines the fluid dynamics of the surface layer. For the heat source located at the surface, the vertical stratification is stable and the flow is driven by a horizontal pressure gradient, formed by non-uniform heating of the liquid along the surface. Experimental studies include measurements of velocity fields using particle image velocimetry, surface relief measurements using moon-glade background oriented Schlieren and surface temperature measurements using infrared thermography. Also, numerical simulations of the flow development are performed and a new similarity solution for the steady state in a laterally unbounded domain is constructed, which takes into account the pressure gradient. The results are shown to be in good agreement with experimental data. The obtained dependencies of the maximal velocity, boundary layer thickness, local and total Nusselt numbers on the Rayleigh number are consistent with literature data obtained for the non-uniformly heated bottom case, which demonstrates universal properties of horizontal convection.

Comparison of Schlieren-based techniques for measurements of a turbulent and wavy free surface

“…To the authors' knowledge, this is the first study to compare the performance of multiple optical techniques for surface reconstruction. The TIR-D and M-G techniques, due to their recency, are featured in limited studies other than the original work (Jain et al, 2022;Jain, Gauthier, Lohse, et al, 2021;Jain, Vega-Martínez, et al, 2021;Kochkin et al, 2022;Mungalov & Derevyannikov, 2021;Rudenko et al, 2022). These techniques have also gone unnoticed in reviews of optical techniques for surface measurements such as a recent comprehensive review by Gomit et al (2022).…”

Modeling of stratified two‐phase flows with non‐uniform evaporation based on the exact solution of convection equations

“…The accuracy of modern experimental measurements of thermophysical characteristics allows one to study the velocity and temperature fields at interfaces, in near-surface layers and liquid volumes, to determine the parameters of the vapor content in the gas phase and the rate of evaporation of the liquid and/or the rate of vapor condensation even when the effects of evaporation are insignificant (i.e., the evaporation of the diffusive type occurs). By now, the databases have been collected, which contain the measurement data on various characteristics of convective flows in the liquid-gas systems [17][18][19][20][21] and physical parameters of working media containing volatile components [22]. Based on the experimental data, the dependencies of the mass flow rate of evaporation occurring under the action of an inert gas flow on the liquid layer height, gas flow rate, and interface temperature for the systems with the working media such as ethanol/HFE-7100 (liquid) and nitrogen/air (gas) were defined.…”

On the interfacial deformations and thermal characteristics exhibiting self-similar behavior under the action of a line heat source

“…The interface deformation results from the induced natural convection set about due to the temperature gradients prevailing between the interface and the liquid bulk. In this direction, as part of efforts made to develop a fundamental understanding of the phenomenon, different configurations of the process have been studied wherein the liquid is heated from the bottom through a plate or a wire (Wang and Huang 2005;Hughes and Griffiths 2008;Rudenko et al 2022). Some studies have included heating or cooling of the interface to study the interface dynamics (Castillo and Velarde 1982;Burelbach et al 1996).…”

“…In another study, Vinnichenko et al measured the surface deformations due to convection currents produced in Rayleigh-Bernard convection through bulk heating and by a heating wire under the interface (Vinnichenko et al 2020). Recently, Rudenko et al carried out a detailed study of near-interface horizontal convection caused by a heating wire along the interface (Rudenko et al 2022). The study was carried out for water which features a stationary surface film, impeding Marangoni convection caused by thermal gradients over the interface.…”