Experimental and theoretical study of vibration-induced thermal convection in low gravity

Abstract

Vibrations acting on a fluid with density gradient induced by temperature variations can cause relative flows. High-frequency vibration leads to the appearance of timeaveraged (mean) flows (or streaming flows), which can essentially affect heat and mass transfer processes. This phenomenon is most pronounced in the absence of other external forces (in particular, static gravity). In this work, an extensive experimental and computational study of thermal vibrational convection in a reduced-gravity environment of a parabolic flight is performed. The transient evolution of the temperature field in a cubic cell subjected to translational vibration is investigated by optical digital interferometry. The mean flow structures previously reported in numerical studies are confirmed. The transition from four-vortex flow to a pattern with a large diagonal vortex and two small vortices is observed in the transient state. The experiments reveal a significant enhancement of heat transfer by vibrational mean flows with increasing the vibrational strength. Three-dimensional direct numerical simulation with real microgravity profile and two-dimensional numerical modelling based on averaging approach provide a very good agreement with the experimental results. The influence of residual gravity on heat transfer and bifurcation scenario is first investigated numerically and correlated with the experimental data. It is demonstrated that gravity effects on non-uniformly heated fluids can be reproduced in weightlessness by applying vibrations to the system.

Experimental and predicted refractive index properties in ternary mixtures of associated liquids

“…These derivatives were determined from the experimental data on refractive indices in ternary mixtures employing a procedure of analytical differentiation of polynomial fitting equations (1) and (2). On the other hand the Newton formula, equation (6), was chosen in order to examine the accuracy of the derivatives calculations using mixing rules.…”

“…The development of high quality lasers has led to the emergence of a wide range of optical experimental methods that make use of refractive index variations. The variation of the refractive index with temperature and concentration is the basis for development of the experimental techniques aimed at studying convection and heat and mass transfer in transparent media [1,2]. The time dependence of the optical characteristics of the system is determined by the rate of heat/ mass diffusion.…”

IVIDIL experiment onboard the ISS

“…The second approach was employed for investigation of the heat transfer by vibrational flow (Shevtsova et al, 2010a). The dimensionless heat flux through the walls (the Nusselt number) is defined as…”

Averaging method and long-wave asymptotics in vibrational convection in layers with an interface

“…Theoretical research in this area helps the researchers to plan how experiments have to be carried out that are intended to discover and take into account vibrational effects, as predicted by theory. This has been done in the case of solid boundaries [15,17,52].…”