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We present a direct numerical simulation (DNS) study of buoyancy-driven bubbly flows in two dimensions. We employ the volume of fluid (VOF) method to track the bubble interface. To investigate the spectral properties of the flow, we derive the scale-by-scale energy budget equation. We show that the Galilei number (Ga) controls different scaling regimes in the energy spectrum. For high Galilei numbers, we find the presence of an inverse energy cascade. Our study indicates that the density ratio of the bubble with the ambient fluid or the presence of coalescence between the bubbles does not alter the scaling behaviour.
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http://dx.doi.org/10.1140/epje/i2020-11997-0 | DOI Listing |
Phys Rev Lett
September 2023
Tata Institute of Fundamental Research, Gopanpally, Hyderabad 500046, India.
We investigate the spectral properties of buoyancy-driven bubbly flows. Using high-resolution numerical simulations and phenomenology of homogeneous turbulence, we identify the relevant energy transfer mechanisms. We find (a) at a high enough Galilei number (ratio of the buoyancy to viscous forces) the velocity power spectrum shows the Kolmogorov scaling with a power-law exponent -5/3 for the range of scales between the bubble diameter and the dissipation scale (η).
View Article and Find Full Text PDFEur Phys J E Soft Matter
November 2020
TIFR Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 500046, Gopanpally, Hyderabad, India.
We present a direct numerical simulation (DNS) study of buoyancy-driven bubbly flows in two dimensions. We employ the volume of fluid (VOF) method to track the bubble interface. To investigate the spectral properties of the flow, we derive the scale-by-scale energy budget equation.
View Article and Find Full Text PDFJ Fluids Eng
October 2020
Department of Chemical and Biological Engineering, Iowa State University, Sweeney Hall, 618 Bissell Rd., Ames, IA 50011.
A numerical investigation is performed on buoyancy-driven homogeneous and heterogeneous bubbly flows to compare the bulk gas-liquid heat transfer effectiveness for Prandtl (Pr) numbers 0.2-20 and void fractions 0.3-0.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
April 2013
Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom.
A lattice Boltzmann model (LBM) is proposed based on the phase-field theory to simulate incompressible binary fluids with density and viscosity contrasts. Unlike many existing diffuse interface models which are limited to density matched binary fluids, the proposed model is capable of dealing with binary fluids with moderate density ratios. A new strategy for projecting the phase field to the viscosity field is proposed on the basis of the continuity of viscosity flux.
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