Turbulent convection is often present in liquids with a kinematic viscosity much smaller than the diffusivity of the temperature. Here we reveal why these convection flows obey a much stronger level of fluid turbulence than those in which kinematic viscosity and thermal diffusivity are the same; i.e., the Prandtl number Pr is unity. We compare turbulent convection in air at Pr=0.7 and in liquid...

We investigate the utility of the convex hull ofmany Lagrangian tracers to analyze transport properties of turbulent flowswith different anisotropy. In direct numerical simulations of statistically homogeneous and stationaryNavier–Stokes turbulence, neutral fluid Boussinesq convection, and MHDBoussinesq convection a comparisonwith Lagrangian pair dispersion shows that convex hull statistics cap...

We present a discussion on the effects of convection on the uvby colours of A and F stars. The mixing-length theory used in ATLAS9 is compared to the turbulent convection theory of Canuto & Mazzitelli (1991, 1992). Comparison with fundamental stars reveals that colours calculated using the Canuto & Mazzitelli convection theory are generally in better agreement than those obtained using mixing-l...

A two-dimensional Boussinesq model of thermal convection is investigated by numerical simulations. The turbulent heat transport is mainly due to thermal plumes. It is shown that their thin, wrinkled interfaces control the statistics of large temperature excursions. Away from the interfaces, the temperature fluctuations are strongly suppressed and the field in those regions is well mixed. Their ...

Deep convection energizes the entire water column. Large-eddy simulation of the oceanic boundary layer system predicts turbulence in the well-mixed layer as well as turbulence-induced internal waves propagating into the underlying stratified water column of the freely convecting wintertime Labrador Sea. Of particular interest is the downward propagation of energy from the turbulent boundary lay...

Computational models are developed to predict the natural convection heat transfer and buoyancy for a Montgolfiere under conditions relevant to the Titan atmosphere. Idealized single and double-walled balloon geometries are simulated using algorithms suitable for both laminar and (averaged) turbulent convection. Steady-state performance results are compared to existing heat transfer coefficient...

High resolution computer simulations of two-dimensional convection using the anelastic approximation are presented. These calculations span Rayleigh numbers from 10(8)-10(12) for Prandtl number equal to unity, with the fluid density decreasing by a factor of 12 from the bottom to the top of the convection region. This range covers several decades in the "hard" turbulent regime. While many studi...

Solar-like oscillations are stochastically excited by turbulent convection. In this work we investigate changes in the acoustic oscillation power spectrum of solar-type stars by varying the treatment of convection in the equilibrium structure and the properties of the stochastic excita-tion model. We consider different stellar models computed with the standard mixing-length description by Böhm-...

High resolution computer simulations of two-dimensional convection using the anelastic approximation are presented. These calculations span Rayleigh numbers from 10 10 for Prandtl number equal to unity, with the uid density decreasing by a factor of 12 from the bottom to the top of the convection region. This range covers several decades in the \hard" turbulent regime. While many studies of thi...

Turbulent motions in the interior of a star play an important role in its evolution, since they transport chemical species, thermal energy and angular momentum. Our overall goal is to construct a practical turbulent closure model for convective transport that can be used in a multidimensional stellar evolution calculation including the effects of rotation, shear and magnetic fields. Here, we fo...