Lattice Boltzmann modelling for immiscible Rayleigh-Taylor turbulence/
Modelagem da turbulência de Rayleigh-Taylor imiscível usando o método Lattice-Boltzmann
Hugo Saraiva Tavares.
- Rio de Janeiro: IMPA, 2020.
- video online
Defesa de Tese Banca: Alexei Mailybaev - Orientador - IMPA Andre Nachbin - IMPA Luca Biferale - Univ. of Roma Fábio Ramos - UFRJ Fabio Pereira dos Santos - EQ-UFRJ Juliana Moreira - COPPE-UFRJ Dan Marchesin - Suplente - IMPA.
Resumo: Rayleigh-Taylor (RT) instability occurs when a lighter fluid is pushing a heavier fluid. We study turbulence induced by the RT instability for two-dimensional immiscible two-component flows by using a multicomponent lattice Boltzmann method. First we develop and test the numerical method. Then, based on numerical simulations implemented on GPUs, we analyze the energy budgets for RT systems. This analysis verifies some important theoretical assumptions about the immiscible RT turbulence using accurate numerical experiments, like the connection between the variation of interface energy and the energy flux due to the Korteweg stress tensor. We also analyze the energy dissipation, showing that the interface acts as a source of vorticity. In the second part of our numerical tests, we approach a phenomenological theory for the immiscible RT turbulence. We extend this theory to the two-dimensional case using the earlier results by Chertkov, Kolokolov and Lebedev (2005) for three-dimensional flows. We compare numerically the growth of the mixing layer, typical velocity, average density profiles and enstrophy between the cases of immiscible and miscible two-component fluids. In addition, we investigate the evolution of typical drop size and the dynamics of interface length in the emulsion-like state, confirming the power-law theoretical predictions. .