We derive an effective medium theory for acoustic wave propagation in bubbly fluid near Minnaert resonant frequency. We start with a multiple scattering formulation of the scattering problem of an incident wave by a large number of identical small bubbles in a homogeneous fluid. Under certain conditions on the configuration of the bubbles, we justify the point interaction approximation and esta...

To improve the existing trial-and-error process in designing a microfluidic T-junction, a systematic study of the geometrical (mainly the channel length) effects on the generated bubbly/slug flow was conducted to figure out basic design guidelines based on experimental and theoretical analyses. A driving system with dual constant pressure sources, instead of the commonly used dual constant volu...

The PHOENICS code is employed to perform numerical simulations of gas-liquid two-phase bubbly flows in large vertical flow channels. Air-water and steam-water flows in large diameter pipes are simulated using the built-in two-fluid option of the code where liquid and gas are modeled as two interacting continua. The code is utilized in conjunction with advanced twophase flow models, accounting f...

Explosive volcanic eruption requires that magma fragments into discrete parcels. Silicic magma can fragment through brittle failure or other processes that depend on the viscoelasticity of the melt. Owing to the low viscosity of basaltic magmas, however, the fragmentation mechanism must be different and will be governed by fluid mechanics alone. We perform a series of decompression experiments ...

Squeeze film dampers are widely used in aircraft engines, land-based gas turbines, and other rotating machines to improve system damping. They often have entrained air within the oil film, which is usually not taken into account in rotordynamics analysis due to lack of good formulations of the effects involved. The effects on the damping force calculation can be significant. This work presents ...

Recent DNS studies of buoyant bubbly flows in vertical channels are discussed. Simulations of nearly spherical bubbly flows in vertical channels show that the bubbles move towards the wall for upflow and away from the wall for downflow in such a way that the core is in hydrostatic equilibrium. For downflow the wall layer is free of bubbles but for upflow there is an excess of bubbles in the wal...

This paper presents an enhancement to the free surface lattice Boltzmann method (FSLBM) for the simulation of bubbly flows including rupture and breakup of bubbles. The FSLBM uses a volume of fluid approach to reduce the problem of a liquid-gas two-phase flow to a single-phase free surface simulation. In bubbly flows compression effects leading to an increase or decrease of pressure in the susp...

The impedance measurement between a pair of flush-mounted electrodes was used to measure the characteristics of a stratified near-wall bubbly flow. The variation in cross electrode impedance with liquid layer thickness and mixture void fraction was examined using numerical simulations and static experiments. The experimental realization of the measurement system was used to measure the solid fr...

We develop a stylized model of economic growth with bubbles. In this model, changes in investor sentiment lead to the appearance and collapse of macroeconomic bubbles or pyramid schemes. We show how these bubbles mitigate the effects of financial frictions. During bubbly episodes, unproductive investors demand bubbles while productive investors supply them. These transfers of resources improve ...

We consider the linear system arising from discretization of the pressure Poisson equation with Neumann boundary conditions, derived from bubbly flow problems. In the literature, preconditioned Krylov iterative solvers are proposed, but they often suffer from slow convergence for relatively large and complex problems. We extend these traditional solvers with the so-called deflation technique, t...