Sharif Digital Repository

Because of the importance of gas-solid fluidized beds in chemical industrial plants, many experimental and modeling efforts have been conducted the prediction of their behaviors up to now. Gas bubbles have a pivotal role in the hydrodynamics of bubbling gas-solid fluidized beds; so, fundamental understanding of the bubbling behavior of fluidized beds is required to describe bubble-related phenomena such as solids mixing and segregation, reaction conversion, heat and mass transfer, erosion of heat-transfer tubes and particle entrainment. In this work, the effects of different parameters such as bed aspect ratio, bed width, superficial gas velocity, and particle size distribution on the... 

The Phenomena of generation and propagation of pressure waves (e.g. sounds) are of fundamental importance in studying fluid dynamics. Conventional computational fluid dynamics (CFD) simulations has always been part of the investigation. On the other hand, the lattice Boltzmann method (LBM) has been developed into an alternative and promising numerical method for simulating sound propagation in heterogeneous media with complex geometries. In this project, propagation of sound waves in a liquid was simulated, using lattice Boltzmann method (LBM) and particularly phononic model. To survey effect of different viscosities on this phenomenon, the kinematic viscosity of the medium was varied and... 

We present a new high signal to noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the 5780Å and 5797Å Diffuse Interstellar Bands (DIBs). We have observed 432 sightlines to a distance of 200 pc over a duration of 3 years. In this study, for both inside and outside the Local Bubble, we establish the 5780and 5797correlations with Na i, Ca iiand E(B-V). The correlations show that among all neutral and ionized atoms, the Na ihas more similarity with 5780and Ca iihas strong correlation with 5797, which suggest that the ionization level of 5797is more than 5780. We study the 5780correlation with 5797, which shows a tight correlation... 

Microfluidics with the ability to control Nano-to-Pico meter volumes have caused the revolution in the systems of analytical biology and chemistry. However, the most Lab-On-Chip technologies (LOCs) depend on external control elements, so a lab is required to operate a chip. Bubble or drop logic through the bubble (drop) can control the flow internally and intrinsically digitally without utilizing of off-chip or moving components. Non-linearity is applied by using mutual drop-drop' effects on reversible linear flow in low Reynolds. for the proper exploitation of microfluidic systems, It is necessary to control droplet generation systems in one chip appropriately. The most crucial part of the...