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Initial instabilities of gravitational flows of non-newtonian liquids

Grant number: 18/03175-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2018
Effective date (End): December 31, 2018
Field of knowledge:Engineering - Mechanical Engineering - Transport Phenomena
Principal Investigator:Erick de Moraes Franklin
Grantee:Lucas Lima da Silva
Home Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil


Gravity-driven flows of liquid films may give rise to surface waves. These waves are created by an instability mechanism involving inertial, gravity and surface tension effects, and are usually called Liquid Film Instability or Kapitza Instability. Some examples are the flows of mud over hills during intense rains, and film flows during painting and application of magnetic liquids on inclined planes. In many cases, such as the just cited, the fluid may be a non-Newtonian one with, sometimes, an unknown rheological behavior. One very complex case is the dense suspension solid particles, where particles are in permanent contact and, therefore, anisotropy is present. Under these conditions, the wavelength and celerities are different from Newtonian fluids. This project proposes an experimental study of instabilities appearing on the surface of a non-Newtonian liquid film flowing by gravity. In order to achieve it, different liquid flows will be controlled and monitored by using an experimental setup developed by the candidate in a previous IC project (FAPESP grant no. 2017/06303-6). The surface instabilities will be measured by the transmissivity of both monochromatic light and infrared waves, using an electronic device developed by the candidate in his precedent IC, as well as by digital cameras and automatic post-treatment. From the experiments, we expect to find the wavelengths and the celerities of surface waves. (AU)