Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
NONLINEAR INSTABILITY ANALYSIS IN STRATIFIED FLOW PATTERN IN LIQUID-LIQUID SYSTEM
Submission Author:
Daniel Krusche , SP
Co-Authors:
Marcelo Souza de Castro
Presenter: Daniel Krusche
doi://10.26678/ABCM.ENCIT2016.CIT2016-0098
Abstract
In multiphase flow to determine the spatial distribution of the phases is a necessary prerequisite. Relative knowledges about the flow pattern affects many technical aspects of engineering. Transition criteria are investigated in function of the range of necessary conditions for the existence of determined pattern. In this article, stratified flow pattern in liquid-liquid system is numerically simulated in order to predict the spatial point where the transition to another flow pattern occurs. Previous studies indicate that this phenomenon is related to the structure of the interfacial wave and happens in space and it is dominated by nonlinear effects. At first, the nonlinear equations of mass and momentum are obtained by the one-dimensional two-fluid model. A simplified nonlinear analysis in hydrodynamic stability is obtained by the method of characteristics and an explicit finite difference scheme, in which the flow is subjected to a solitary wave (saturated wave) with dimensions based on previous studies and its propagation is defined in time-space plane. For the development of interfacial wave the effects caused by interface curvatures in the direction of flow and the cross section are considered. Such effects are related to interfacial tension and are essentials in liquid-liquid flow systems. Due to inclusion of interfacial terms two new constants must be defined as functions and used to force the breakup of the wave at the point experimentally observed. The results are intended to improve the transition models between flow patterns and are validated by comparison with experimental works.
Keywords
Liquid-liquid flow, Stratified flow pattern, Waves, hydrodynamic stability, Transition Boundaries, Method of characteristics
