Convective mixing in porous media is triggered by a Rayleigh-Bénard-type hydrodynamic instability as a result of an unstable density stratification of fluids. While convective mixing has been studied extensively, the fundamental behavior of the dissolution flux and its dependence on the system parameters are not yet well understood. Here, we show that the dissolution flux and the rate of fluid ...

We report the results of high-resolution direct numerical simulations of two-dimensional Rayleigh-Bénard convection for Rayleigh numbers up to Ra=10;{10} in order to study the influence of temperature boundary conditions on turbulent heat transport. Specifically, we considered the extreme cases of fixed heat flux (where the top and bottom boundaries are poor thermal conductors) and fixed temper...

The effect of the temperature and initial hydrostatic stress has been shown on the propagation of Rayleigh waves in a viscoelastic half-space. It has been explained how the velocity of Rayleigh waves depends not only on the parameters pertaining to the viscoelastic properties of the half-space, but on the temperature and the initial hydrostatic stress of the half-space also. The variations of t...

It is well known that scattering lidars, i.e., Mie, aerosol-wind, Rayleigh, high-spectral-resolution, molecular-wind, rotational Raman, and vibrational Raman lidars, are workhorses for probing atmospheric properties, including the backscatter ratio, aerosol extinction coefficient, temperature, pressure, density, and winds. The spectral structure of molecular scattering (strength and bandwidth) ...

This paper presents theoretical and experimental results on the problem of bounded acoustic beam reflection at the Rayleigh angle from a fluid-solid interface which is loaded by a thin solid layer. The theoretical development exploits the framework of existing theory to yield a simple, analytic model which is reasonably accurate for thin layers. It is shown that the influence of the layer is co...

In this paper Bit Error Rate performance of QPSK modulation and OFDM -QPSK System over AWGN and Rayleigh fading channel is analyzed. The performance of BER of QPSK over AWGN and Rayleigh channel is compared. OFDM is an orthogonal frequency division multiplexing to reduce intersymbol interference problem. Simulation of QPSK signals is carried with both AWGN and Rayleigh channel. Finally simulati...

We consider double-diffusive convection between two parallel plates and compute bounds on the flux of the unstably stratified species using the background method. The bound on the heat flux for Rayleigh–Bénard convection also serves as a bound on the double-diffusive problem (with the thermal Rayleigh number equal to that of the unstably stratified component). In order to incorporate a dependen...

We consider the Rayleigh–Taylor instability in the early evolution of the rarefied radio bubbles (cavities) observed in many cooling–flow clusters of galaxies. The top of a bubble becomes prone to the Rayleigh–Taylor instability as the bubble rises through the intra–cluster medium (ICM). We show that while the jet is powering the inflation, the deceleration of the bubble–ICM interface is able t...

In this letter, we provide an asymptotic error rate performance evaluation of space-time block codes from coordinate interleaved orthogonal designs (STBCs-CIODs), especially in shadowed Rayleigh fading channels. By evaluating a simplified probability density function (PDF) of Rayleigh and Rayleigh-lognormal channels affecting the STBC-CIOD system, we derive an accurate closed-form approximation...

An assessment of spectrum efficiency for a microcellular land mobile radio system is presented by considering the desired signal as (fast) Rician fading with (slow) lognormal shadowing and co-channel interfering signals as uncorrelated (fast) Rayleigh fading superimposed over (slow) lognormal shadowing. Spectrum efficiency is defined in terms of reuse distance, Le., cluster size, traffic intens...