Труды Института механики им. Р.Р. Мавлютова

Iulmukhametova R.R., Tukhbatova E.R., Musin A.A., Kovaleva L.A. Research of the thermal convection influence on the process of water-in-oil emulsion stratification. Proceedings of the Mavlyutov Institute of Mechanics. 2017. 12(2). 163–168.

2017. Vol. 12. Issue 2, Pp. 163–168
URL: http://proc.uimech.org/uim2017.2.024
DOI: 10.21662/uim2017.2.024

Research of the thermal convection influence on the process of water-in-oil emulsion stratification

Iulmukhametova R.R., Tukhbatova E.R., Musin A.A., Kovaleva L.A.

Bashkir State University, Ufa

Abstract

The results of numerical modeling of the effect of temperature on the dynamics of the water droplets’ sedimentation in a water-in-oil emulsion in the field of gravitational forces are presented in the article. The mathematical model is based on the system of equations of thermal convection in the Boussinesq approximation with the addition of the diffusion equation. The simulation was carried out in the open software platform OpenFOAM by the control volume method. Numerical calculations take into account the thermal convection of the emulsion system. It is shown that the convective flows arising in the liquid affect the process of stratification of the water-in-oil emulsion. To estimate the simulation results dimensionless parameters of Rayleigh and Archimedes were introduced.

Keywords

water-in-oil emulsion,
thermal convection,
emulsion stratification,
OpenFOAM

Article outline

Purpose: Numerical study of thermal convection influence on the process of water-in-oil emulsion stratification.

Methodology: The modeling of the problem is carried out in free and open-source software OpenFoam. The mathematical model is written in the diffusion approximation and includes the system of equations of thermal convection in the Boussinesq approximation and the diffusion equation. |

As a result of the study, it is found that:

1. At small values of the Rayleigh number (less than 10³) the emulsion is completely stratified at any value of the Archimedes number.

2. Thermoconvective flow arises in the medium at an increase of the Rayleigh number and begins to mix the emulsion system intensively. Thus, it has a negative effect on the water-in-oil emulsion stratification process. However, an increase in the value of the Archimedes number at a constant value of the Rayleigh number leads to a complete stratification of the emulsion system.

3. It is found that the character of the sedimentation dynamics of the water droplets in the emulsion changes when critical values of the Rayleigh number are reached, when the structure of the flow changes and additional vortices form.

4. A graph of the complete stratification of the water-in-oil emulsion is constructed at the presence of thermal convection in the liquid when vessel is heated from below, and it allows estimating the intensity of destruction of the emulsion under thermal action.