in present paper, dynamic behavior and control of a fluidized bed reactor for polyethylene production has been considered. a double active sites model for ziegler-natta catalysts is used for simulation of polymerization reaction. hydrodynamic behavior of the bed is modeled using a two phase model including bubble and emulsion phases in which bubble phase has plug flow pattern with differentiall...

The low-frequency sound speed in a fluid-like kaolinite sediment containing air bubbles was measured using an acoustic resonator technique and found to be 114 ms with negligible dispersion between 100 and 400 Hz. The sediment's void fraction and bubble size distribution was determined from volumetric images obtained from x-ray computed tomography scans. A simplified version of Wood's effective ...

purpose: to investigate the results of deep lamellar keratoplasty (dlk) by big bubble method with using shifting bubble sign in patients suffering from keratoconus or corneal opacity methods: in this prospective interventional clinical trial, 20 eyes of 18 patients (10 males and 8 females) who underwent dlk by big bubble method using shifting bubble sign were investigated. mean age of cases wer...

A bubble reaching an air-liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R≫100 μm. However, few studies have been devoted to small bubbles (R<100 μm) despite the entrainment of a large number of such bubbles in sea water. Here we ...

We report experiments on lateral migration of bubbles in a two-dimensional foam sheared in a narrow-gap Couette device. A larger bubble in an otherwise monodisperse bubble raft migrates toward the center of the gap as long as the bubble size ratio and the shear rate are each above a threshold. The migration speed is roughly two orders of magnitude higher than that of a single bubble, and increa...

Surface cleaning using cavitation bubble dynamics is investigated numerically through modeling of bubble dynamics, dirt particle motion, and fluid material interaction. Three fluid dynamics models; a potential flow model, a viscous model, and a compressible model, are used to describe the flow field generated by the bubble all showing the strong effects bubble explosive growth and collapse have...

Laser-assisted killing of gold nanoparticle targeted macrophages was investigated. Using pressure transient detection, flash photography and transmission electron microscopy (TEM) imaging, we studied the mechanism of single cell damage by vapor bubble formation around gold nanospheres induced by nanosecond laser pulses. The influence of the number of irradiating laser pulses and of particle siz...

The performance of microflotation, dispersed air flotation with microbubble clouds with bubble size about 50 µm, for algae separation using fluidic oscillation for microbubble generation is investigated. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterization results showed t...