The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The s...

The buoyant rise of thermals (i.e. bubbles of enhanced entropy, but initially in pressure equilibrium) is investigated numerically in three dimensions for the case of an adiabatically stratified layer covering 6–9 pressure scale heights. It is found that these bubbles can travel to large heights before being braked by the excess pressure that builds up in order to drive the gas sideways in the ...

We explore the microfluidic generation of bubbles in a flow-focusing junction using a pressure-controlled device rather than the more common flow ratecontrolled devices. This device is a prototype for extending microfluidic drop generation methods to molten polymers. We show that the bubble generation process is highly sensitive to pressure: small changes in pressure induce large changes in bub...

The buoyant rise of thermals (i.e. bubbles of enhanced entropy, but initially in pressure equilibrium) is investigated numerically in three dimensions for the case of an adiabatically stratified layer covering 6–9 pressure scale heights. It is found that these bubbles can travel to large heights before being braked by the excess pressure that builds up in order to drive the gas sideways in the ...

computational scheme is used to study the bubble trajectories. The 2D averaged Navier stokes equations are solved. The SIMPLEC algorithm is used to relate the pressure to velocity. A one-way coupling is assumed and the effects of the bubbles on carrier flow are neglected. The bubble equation of motion includes the drag, buoyancy, pressure gradient, Saffman lift and bubble volume change forces. ...

We report an experimental study of bubble dynamics in a non-Newtonian fluid subjected to a pressure decrease. The fluid is a hydrogel, composed of water and a synthetic clay, prepared and sandwiched between two glass plates in a Hele-Shaw geometry. The rheological properties of the material can be tuned by the clay concentration. As the imposed pressure decreases, the gas initially dissolved in...

The surface stability problem of an encapsulated microbubble in an ultrasound field is numerically addressed. To predict the nonlinear process, the continuity equation and Navier-Stokes equation are directly solved by means of a boundary-fitted finitevolume method on an orthogonal curvilinear coordinate system. The bubble is insonified by an ultrasound pulse consisting of a burst of 10 cycles, ...

Following the first shock wave generation and the successive single bubble expansion after the breakdown by the Nd:YAG laser pulse with 35 mJ and 10 ns in distilled water, the strong secondary shock wave is generated at the instant of the bubble collapse. The single bubble expands up to 0.59 mm in radius, and then closes up by the pressure difference between the ambient liquid pressure at 10 kP...

Spherically collapsing cavitation bubbles produce a shock wave followed by a rebound bubble. Here we present a systematic investigation of the energy partition between the rebound and the shock. Highly spherical cavitation bubbles are produced in microgravity, which suppresses the buoyant pressure gradient that otherwise deteriorates the sphericity of the bubbles. We measure the radius of the r...

When water flows through hydraulic turbomachines, the local pressure can become low enough to vaporize the water and create vapor cavities. This phenomenon is called cavitation. When the cavities collapse, shock waves and liquid jets traveling through the inclusions can erode nearby solid surfaces. The collapse of cavitation bubbles has been extensively investigated in the case of a single bubb...