Disentangle plume-induced anisotropy in the velocity field in buoyancy-driven turbulence

Abstract

We present a method of disentangling the anisotropies produced by the cliff structures in turbulent velocity field and test it in the system of turbulent Rayleigh-Bénard (RB) convection. It is found that in the RB system the cliff structures in the velocity field are generated by thermal plumes. These cliff structures induce asymmetry in the velocity increments, which leads us to consider the plus and minus velocity structure functions (VSF). The plus velocity increments exclude cliff structures, while the minus ones include them. Our results show that the scaling exponents of the plus VSFs are in excellent agreement with those predicted for homogeneous and isotropic turbulence (HIT), whereas those of the minus VSFs exhibit significant deviations from HIT expectations in places where thermal plumes abound. These results demonstrate that plus and minus VSFs can be used to quantitatively study the effect of cliff structures in the velocity field and to effectively disentangle the associated anisotropies caused by these structures.

10 pages, 5 figures

References in corpus (5)

• Large scale dynamics in turbulent Rayleigh-Benard convection
• Experimental Investigation of Longitudinal Space-Time Correlations of the Velocity Field in Turbulent Rayleigh-Bénard Convection
• Universality of anisotropic fluctuations from numerical simulations of turbulent flows
• Comparative experimental study of local mixing of active and passive scalars in turbulent thermal convection
• Anomalous scaling of a passive scalar advected by the turbulent velocity field with finite correlation time and uniaxial small-scale anisotropy

Cited by in corpus (2)

• Temporal evolution and scaling of mixing in two-dimensional Rayleigh-Taylor turbulence
• Revisiting the role of intermittent heat transport towards Reynolds stress anisotropy in convective turbulence