This paper presents measurements and model predictions of the density and size distribution of bubbles in the wakes of full scale ships, and the effects of the bubbles on acoustic propagation. The ship wake is primarily a hydrodynamic process, characterized by temporally and spatially varying flow conditions (i.e., local fluid velocity, pressure, turbulent kinetic energy and dissipation, etc.) ...

Industrial bubble column reactor for Fischer-Tropsch (FT) synthesis includes complex hydrodynamic, chemical and thermal interaction of three material phases: population of bubbles of different sizes, liquid and catalyst particles suspended in liquid. To simulate FT bubble column, a Computational Fluid Dynamics model is described here. The model is based on Eulerian multifluid formulation and ac...

The effects of fluid viscoelasticity on the expansion of gas bubbles in polymer foams for the cases of reactive and non-reactive polymers are investigated. For non-reactive polymers, bubble expansion is controlled by a combination of gas diffusion and fluid rheology. In the diffusion limited case, the initial growth rate is slow due to small surface area, whereas at high diffusivity initial gro...

We have used a 100 000 frame-per-second video to analyze the pinch-off of nitrogen gas bubbles in fluids with a wide range of viscosity. If the external fluid is highly viscous (eta(ext)>100 cP), the bubble neck radius is proportional to the time before break, tau, and decreases smoothly to zero. If the external fluid has low viscosity (eta(ext)<10 cP), the radius scales as tau(1/2) until an in...

This Brief Report presents experimental and computational results on bubble formation in microfluidic devices. Bubbles are generated at the right-angle intersection of four identical square microchannels. When the pressure gradient generated by the liquid flow dominates the pressure gradient generated by gas flow, the length of the produced confined bubbles follows a law based on the channel si...

We conducted rapid decompression experiments using bubble-bearing viscoelastic fluid in a vertical shock tube. We varied vesicularity / and pressure difference between the inside Pg and the outside Po of the bubbles, DP=Pg Po, to understand the behavior of bubbly-magmas under rapid decompression. We find that the potential energy, which depends on the initial vesicularity /, Pg, and Po, determi...

9 A surprising phenomenon witnessed by many is the sinking bubbles seen in a settling pint of 10 stout beer. Bubbles are less dense than the surrounding fluid so how does this happen? Previous 11 work has shown that the explanation lies in a circulation of fluid promoted by the tilted sides of the 12 glass. However, this work has relied heavily on computational fluid dynamics (CFD) simulations....

In this research, the effect of bubble surface area flux, Sb, and particle size on flotation rate constant, k, of pyrite (FeS2) particles was studied using bubble-particle interactions. The bubble-particle collision, attachment and detachment efficiencies were calculated under different flow regimes. The k increased with increase in the collision efficiency and decreas...

The complex dynamics of a single bubble of a few millimeters in size oscillating inside a narrow fluid-filled gap between two parallel plates is studied using high-speed videography. Two synchronized high-speed cameras were used to observe both the side and front views of the bubble. The front-view images show bubble expansion and collapse with the formation of concentric dark and bright rings....