The effect of design parameters on the flow pattern in a three-phase bubble column by means of Computational Fluid Dynamics (CFD) has been studied. The simulations were performed for air-water-glass beads in a bubble column of H = 0.6 m, D = 0.1 m and ds = 0.05 m to study the flow pattern. Eulerian–Eulerian three-phase simulations with kturbulence for liquid phase were carried out using the com...

An investigation of surface cleaning using a swarm of gas bubbles within an acoustically activated stream is presented. Electrolysis of water at Pt microwires (100 μm diameter) to produce both hydrogen and oxygen bubbles is shown to enhance the extent of ultrasonic surface cleaning in a free flowing water stream containing an electrolyte (0.1 M Na2SO4) and low surfactant concentration (2 mM SDS...

The breakup of a millimetre size buoyantly rising bubble encountering a horizontal plane turbulent jet is experimentally investigated using high-speed shadowgraphy and acoustic techniques. The bubble diameter to jet height ratio is 0.75 and the jet height based Reynolds number is 4000. The high-speed imaging was recorded at 7 kHz simultaneous with hydrophone output at 100 kHz. Bubble breakup ev...

Over the last half of the twentieth century, a number of purely empirical and mechanismbased correlations have been developed for pool nucleate boiling. Empirical correlations differ from each other substantially with respect to the functional dependence of heat flux on fluid and surface properties, including gravity. The mechanism-based correlations require knowledge of the number density of a...

Cavitation associated with the impact of a sphere on a flat surface is investigated using high-speed photography. The sphere, of diameter 15 or 45 mm and made from Ertacetal or stainless steel, was fully submerged and accelerated using a spring-loaded mechanism to achieve Reynolds numbers based on impact velocity and sphere radius of up to 7.2×10. The static pressure and impact velocity were va...

The hydrodynamics of the implosion and rebound of a small (10 lm diameter) air bubble in water was studied using a three-dimensional direct numerical simulation (DNS). To study this problem, we developed a novel stabilized finite element method (FEM) employing a combination of ghost fluid and level set approaches. This formulation treats both the air and water as compressible fluids. Using this...

Rapid Marangoni flows around a water vapor microbubble (WVMB) is investigated using the thermoplasmonic effect of a gold nanoisland film (GNF). By focusing a laser onto the GNF, a stable WVMB with a diameter of ~10 μm is generated in degassed water, while an air bubble generated in non-degassed water is larger than 40 μm. Under continuous heating, the WVMB involves significantly rapid Marangoni...

Experimental bubble size distributions and bubble mean diameters were obtained by means of a photographic technique for a direct-contact evaporator operating in the quasi-steady-state regime. Four gas superficial velocities and three different spargers were analysed for the air-water system. In order to assure the statistical significance of the determined size distributions, a minimum number o...

High-speed photography was used to study the collapse of a confined two-dimensional, air cavity in water, subjected to a propagating pressure disturbance. The 5–6 mm diameter cavity was confined in a rectangular duct. A sustained pressure disturbance was created by an accelerating piston in contact with the water 240 mm away from the bubble. The pressure increased from 0.1 MPa to about 0.12 MPa...

PURPOSE Cavitation of pulmonary metastases have been reported by several authors either as a spontaneous phenomenon or as a consequence of chemotherapy. We present two cases, with this type of image in follow-up, and 20-45 months after the end of treatment. This was the first sign of pulmonary metastases. RESULTS Two patients with osteogenic sarcoma developed radiological evidence of pulmonar...