In this paper, we perform a systematic multiscale analysis for convection dominated transport equations with a weak diffusion and a highly oscillatory velocity field. The paper primarily focuses on upscaling linear transport equations. But we also discuss briefly how to upscale two-phase miscible flows, in which case the concentration equation is coupled to the pressure equation in a nonlinear ...

We perform Large eddy simulations of turbulent compressible convection in stellar-type convection zones by solving the Naviér-Stokes equations in three dimensions. We estimate the extent of penetration into the stable layer above a stellar-type convection zone by varying the rotation rate (Ω), the inclination of the rotation vector (θ) and the relative stability (S) of the upper stable layer Th...

Just as correlations between fluctuating radial and azimuthal velocities produce a coherent stress contributing to the angular momentum transport in turbulent accretion disks, correlations in the velocity and temperature fluctuations produce a coherent energy flux. This nonadvective thermal energy flux is always of secondary importance in thin radiative disks, but cannot be neglected in nonradi...

[1] Observations of Enceladus by the Cassini spacecraft indicate that this tiny Saturnian moon is geologically active, with plumes of water vapor and ice particles erupting from its southern polar region. This activity suggests that tidal dissipation has become spatially localized, perhaps due to a compositional, rheological, and/or thermal anomaly in its ice shell. Here we examine the role tha...

The Sun and the giant planets rotate and possess deep shells of convection. Some basic aspects of prototypical global convection have been studied with a laboratory model operated in the microgravity environment of Spacelab 3 that flew on the space shuttle Challenger in May 1985. This experiment studied thermally driven circulations within a rotating hemispherical shell of fluid across which ar...

We study the partial regularity of a 3D model of the incompressible Navier-Stokes equations which was recently introduced by the authors in [11]. This model is derived for axisymmetric flows with swirl using a set of new variables. It preserves almost all the properties of the full 3D Euler or Navier-Stokes equations except for the convection term which is neglected in the model. If we add the ...

Nano-suspensions (NS) exhibit unusual thermophysical behaviors once interparticle aggregations and the shear flows are imposed, which occur ubiquitously in applications but remain poorly understood, because existing theories have not paid these attentions but focused mainly on stationary NS. Here we report the critical role of time-dependent fractal aggregation in the unsteady thermal convectio...

The primary aim of the current study is to enhance stability and accuracy Volume-Of-Fluid (VOF) method for modeling free-surface flows with large topological changes high density ratio. For accurate capturing fluid interfaces, a novel higher-order bounded convection scheme first constructed based on total variation diminishing (TVD) concept then employed discretization terms in Navier-Stokes, e...

We have developed novel instrumentation for making Lagrangian measurements of temperature in diverse fluid flows. A small neutrally buoyant capsule is equipped with on-board electronics which measures temperature and transmits the data via a wireless radio frequency link to a desktop computer. The device has 80 dB dynamic range, resolving millikelvin changes in temperature with up to 100 ms sam...