A theoretical approach proposed in Phys. Rev. E 66, 066305 (2002) is developed further to investigate formation of large-scale coherent structures in a non-rotating turbulent convection via excitation of a large-scale instability. In particular, the convective-wind instability that causes formation of large-scale coherent motions in the form of cells, can be excited in a shear-free regime. It w...

Coherent large-scale circulations of turbulent thermal convection in air have been studied experimentally in a rectangular box heated from below and cooled from above using Particle Image Velocimetry. The hysteresis phenomenon in turbulent convectionwas found by varying the temperature difference between the bottom and the top walls of the chamber (the Rayleigh number was changed within the ran...

force convection heat transfer of turbulent nano fluid flow in 90 and 60 degree elbow is simulated by using fluent. single phase model has been implemented to study such a flow field and standard

laminar mixed convection of aluminium oxide (al2o3)–water nanofluid flow in an inclined annulus using a single-phase approach was numerically studied. constant heat flux boundary conditions were applied on the inner and outer walls. all the thermophysical properties of nanofluid, such as, viscosity, heat capacity, thermal conductivity, and thermal expansion coefficient, except density in the bo...

in this paper, mixed convection of al2o3-eg-water nanofluid in a square lid-driven enclosure is investigated numerically. the focus of this study is on the effects of variable thermophysical properties of the nanofluid on the heat transfer characteristics. the top moving and the bottom stationary horizontal walls are insulated, while the vertical walls are kept at different constant temperature...

This study discusses the application of Taguchi method in assessing minimum entropy generation and maximum heat transfer rate for natural convection in an enclosure embedded with isothermal cylinder. The simulations were planned based on Taguchi’s L25 orthogonal array with each trial performed under different conditions of position and aspect ratio (AR) of the cylinder. The thermal lattice Bolt...

We consider vertical heat transport in Keplerian accretion disks, including the effects of radiation, convection, and turbulent mixing driven by the Balbus-Hawley instability, in astronomical systems ranging from dwarf novae (DNe), and soft X-ray transients (SXTs), to active galactic nuclei (AGN). In order to account for the interplay between convective and turbulent energy transport in a shear...

Excitation of solar-like oscillations is attributed to turbulent convection and takes place at the upper-most part of the outer convective zones. Amplitudes of these oscillations depend on the efficiency of the excitation processes as well as on the properties of turbulent convection. We present past and recent improvements on the modeling of those processes. We show how the mode amplitudes and...

A variety of chaotic flows evolving in relatively high-dimensional spaces are considered. It is shown through the use of an optimal choice of basis functions, which are a consequence of the Karhunen-Loeve procedure, that an accurate description can be given in a relatively low-dimensional space. Particular examples of this procedure, which are presented, are the Ginzburg-Landau equation, turbul...