Evaluation of bubble growth, sliding and detachment in shear flows

• Grant number: 24/05743-6
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: July 01, 2024
• End date: August 31, 2024
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Gherhardt Ribatski
• Grantee: Ana Elisa Leonel Ferreira
• Supervisor: Catherine Nicole Moll Colin
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: Institut National Polytechnique De Toulouse, France
• Associated to the scholarship: 22/15785-2 - Numerical model development and experimental evaluation of a heat exchanger manufactured by additive manufacturing operating with supercritical CO2, BP.IC

Abstract

Recent studies have proved that heat transfer during nucleate boiling processes is intrinsically related to the fluid motion near to the surface. Bubbles growth and detachment act as stirring agents of the liquid phase. Therefore, a better understanding of the bubble growth, detachment and its flow behavior within the liquid is necessary to model heat transfer under boiling conditions. It is well known that buoyance effects due to the density difference between the liquid and vapor phases, evaporation inertia associated to the liquid displacement during bubble growth and bubble retention due to the surface tension are important mechanisms affecting the bubble lifecycle, and, consequently, the liquid motion. Besides this, in case of convective boiling, bubbles are subject to drag effects under conditions of shear flows within the boundary layer. Most recently coalescence-induced jumping of isolated bubbles from the heated surface has been proposed as an additional mechanism influencing liquid movement. In the present proposal, the student will have access and be trained to use the codes developed by a consortium of European institutions, including the Institut de Mécanique des Fluides de Toulouse (IMFT), to evaluate bubbles growth, detachment, and displacement within the liquid. Once she has learned how to use the code, she will apply it to a broad database available at IMFT obtained by an International Consortium involving 8 countries. This database is composed of high-speed two-phase flow images for µg conditions obtained at the International Space Station and for normal-g conditions. Based on these data, semi-empirical models for bubbles growth and motion will be developed and incorporated into heat transfer models to be developed based on the heat transfer data obtained by the student at EESC-USP.