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Kolmogorov turbulence in buoyancy driven bubbly flows

Time: Thu 2022-08-18 10.30

Location: Faxén, Teknikringen 8

Participating: Vikash Pandey (Nordita)

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Abstract: Bubble laden flow appears in a variety of natural and industrial processes. A suspension of rising bubbles at moderate volume fractions generates chaotic spatiotemporal flow patterns also known as pseudo-turbulence or bubble-induced agitation. As is typical for chaotic flows, pseudo-turbulence is characterized by its kinetic energy spectrum, \(E(k)\), which shows a power law scaling \(E(k)\sim k^{-\alpha}\)with an exponent \(\alpha\) ≳ 3 for scales greater than the bubble diameter. A detailed scale-by-scale energy budget analysis reveals that the scaling is because of the balance of advective nonlinearity and the surface tension with the viscous forces. As the Galilei number (ratio of the buoyancy to viscous forces) is increased, the kinetic energy spectrum shows the Kolmogorov scaling with a power-law exponent −5/3 followed by the pseudo-turbulent −3 scaling.

Bio: Dr. Vikash Pandey has obtained his PhD from Tata Institute of Fundamental Research, Hyderabad, India. Currently he is a postdoctoral fellow at NORDITA, Stockholm.