
Prof. Skryleva Evgeniya
Lomonosov Moscow State University, Russia
Title: Numerical and experimental modeling of multi-phase flows in microgravity
Abstract:
The study of liquid seepage in microgravity conditions is relevant for both space technologies and terrestrial applications. Under conditions of reduced gravity, the main driving force during imbibition of a porous medium is capillary forces. When liquid percolates through a porous medium under terrestrial conditions, capillary effects can have a significant influence on the seepage process. At the same time, the study of capillary effects under conditions of ordinary gravity is difficult: in large pores and channels, where seepage is easily visualized, capillary effects are not strong enough and are masked by gravitational forces; Flow in small pores and channels is difficult to visualize and is also affected by gravity. Therefore, studying the flow of liquids under the influence of capillary forces in microgravity conditions, where capillary effects can be observed “in their pure form,” makes it possible to study the fundamental features of this phenomenon and develop verified mathematical models for more accurate modeling of the seepage process, including in terrestrial conditions. On space stations, flow under the action of capillary forces is observed in various devices, for example: heat pipes, devices for supplying fuel and other liquids from a reservoir, hydroponic devices for growing plants. Conducting experiments in microgravity conditions is difficult and expensive, so the development of mathematical models and software packages for simulating flow processes caused by capillary forces is an extremely urgent task.
This lecture describes two types of experiments: during parabolic flights of an aircraft and experiments in low-Earth orbit. The results of processing experimental data are presented, mathematical models are proposed to describe capillary imbibition, the results of numerical calculations are compared with the results of experiments. An analysis is also made of in which cases it is necessary to take capillary pressure into account.
The lecture also describes the possibility of simulating microgravity conditions on the Earth when studying multiphase flows, namely the Hele-Shaw cell is considered. A series of experiments on stable displacement from a cell is described. The discrepancy between experimental data and analytical solutions based on the generally accepted mathematical model for describing flows in a Hele-Shaw cell is shown. A modified mathematical model with a correction coefficient of resistance, which is determined empirically, is proposed. The new semi-empirical model gives good agreement with experimental data. The results of numerical simulation of unstable flow in the Hele-Shaw cell are also presented.
Biography: