Context. Subcritical transition to turbulence in Keplerian accretion disks is still a controversial issue and some theoretical progress is required in order to determine whether or not this scenario provides a plausible explanation for the origin of angular momentum transport in non-magnetized accretion disks. Aims. Motivated by the recent discoveries of exact nonlinear steady self-sustaining s...

Effects of inclination angle on natural convection heat transfer and fluid flow in a two-dimensional enclosure filled with Cu-nanofluid has been analyzed numerically. The performance of nanofluids is tested inside an enclosure by taking into account the solid particle dispersion. The angle of inclination is used as a control parameter for flow and heat transfer. It was varied from = 0 to = 120 ...

Convection of an internally heated fluid, confined between top and bottom plates of equal temperature, is studied by direct numerical simulation in two and three dimensions. The unstably stratified upper region drives convection that penetrates into the stably stratified lower region. The fraction of produced heat escaping across the bottom plate, which is one half without convection, initially...

The aspect ratio (Γ) dependence of the heat transfer (Nusselt number Nu in dimensionless form) in turbulent (two-dimensional) Rayleigh-Bénard convection is numerically studied in the regime 0.4≤Γ≤1.25 for Rayleigh numbers 10(7)≤Ra≤Ra(9) and Prandtl numbers Pr=0.7 (gas) and 4.3 (water). Nu(Γ) shows a very rich structure with sudden jumps and sharp transitions. We connect these structures to the ...

The heat transfer rate from an isothermal vertical plate placed next to saturated high permeability porous media is studied experimentally and analytically. The media used arc polyurethane foams saturated with air. An integral method is applied in predicting the heat transfer rate by including the non-Darcy effects, which are expected to be significant for high permeabilities and high Rayleigh ...

Alamouti code is a simple space-time code that can be used for transmit diversity systems. This is a class of easily decoded space-time codes that achieve full diversity order in Rayleigh fading channels. Alamouti code exist only for certain numbers of transmit antennas and do not provide array gain like diversity techniques that exploit transmit channel information. When Channel State Informat...