The interaction between sound and ultrasound waves in a weakly compressible viscous liquid with gas bubbles is considered. Using the method of multiple scales oneand two-dimensional nonlinear interaction equations are derived. The degeneracy of the interaction is found in bubbly fluids. This phenomenon lies in the fact that the interaction coefficients vanish at a certain frequency of ultrasoun...

Closure relations are presented for the lift coe.cient for ordered arrays of 2-D and 3-D bubbles at various bubble volume fractions. These were determined via lattice Boltzmann simulations of bubble rise in periodic boxes, where the bubbles were also subjected to shear. The single-bubble lift coe.cient, determined by low-shear computational experiments, varies in a systematic manner with the as...

At the end of the sixties, it was shown that pressure waves in a bubbly liquid obey the KdV equation, the nonlinear term coming from convective acceleration and the dispersive term from volume oscillations of the bubbles. For a variable u, proportional to -p , where p denotes pressure, the appropriate KdV equation can be casted in the form ut 6uu~ + u ~ = 0. The theory of this equation predicts...

We describe a simple model of a bubbly two-phase flow which is able to explain why waves propagate downward when a pint of Guinness is poured, and also how the waves are generated. Our theory involves a physically based regularization of the basic equations of the two-phase flow, using interphasic pressure difference and virtual mass terms, together with bulk or eddy viscosity terms. We show th...

A model for simulating three dimensional polydisperse two-fluid open bubbly flows is presented. The polydisperse model is based on an integro-differential equation for the bubble size distribution function. A multigroup approach is used to discretize the equations in groups of constant mass. The resulting system has four scalar equations (mass and momentum) for the liquid phase and for each gro...

A hydraulic jump is a sudden, rapid transition from a supercritical flow to a subcritical flow. At large inflow Froude numbers, the jump is characterized by a significant amount of entrained air. For this paper, the bubbly two-phase flow properties of steady and strong hydraulic jumps were investigated experimentally. The results demonstrate that the strong air entrainment rate and the depth-av...

The paper discusses first current computational trends related to reactor safety problems and developments needed, as well as the need for new kinds of much more detailed experimental data for the validation of the new methods and codes. The numerous bubbly flow experiments conducted during the last decade at PSI are then reviewed and put in perspective with regards to the needs of the analysts...