Lagrangian dispersion and heat transport in convective turbulence

Abstract

Lagrangian studies of the local temperature mixing and heat transport in turbulent Rayleigh-Benard convection are presented, based on three-dimensional direct numerical simulations. Contrary to vertical pair distances, the temporal growth of lateral pair distances agrees with the Richardson law, but yields a smaller Richardson constant due to correlated pair motion in plumes. Our results thus imply that Richardson dispersion is also found in anisotropic turbulence. We find that extremely large vertical accelerations appear less frequently than lateral ones and are not connected with rising or falling thermal plumes. The height-dependent joint Lagrangian statistics of vertical acceleration and local heat transfer allows us to identify a zone which is dominated by thermal plume mixing.

5 pages, 5 Postscript figures 5 pages, 5 Postscript figures

References in corpus (1)

• Multifractal statistics of Lagrangian velocity and acceleration in turbulence

Cited by in corpus (6)

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• Intermittency in the relative separations of tracers and of heavy particles in turbulent flows
• Lagrangian heat transport in turbulent three-dimensional convection
• Lagrangian tracer dynamics in a closed cylindrical turbulent convection cell
• Large-scale circulations in a shear-free convective turbulence: Mean-field simulations