Ricerc@Sapienza

A novel design for the classical microfluidic device known as T-junction is proposed with the purpose of obtaining a simultaneous measurement of the in-plane velocity components in two orthogonal planes. A crucial feature of the proposed configuration is that all three velocity components are available along the intersection of the two planes. A dedicated optical set-up is developed to convey the two simultaneous views from the orthogonal planes into the sensor of a single camera, where a compound image is formed showing on either half one of the two views.

The nucleation of vapour bubbles in stretched or overheated (metastable) liquids is a complex phenomenon with a wide spectrum of applications. Several models, with different levels of detail, have been proposed to predict the key features of bubble dynamics from bubble formation up to its growth, transport and deformation. Most of them focus separately on a few of these aspects.

Heterogeneous nucleation is the most effective mechanism for the inception of phase transformation. Solid walls and impurities act as a catalyst for the formation of a new thermodynamic phase by reducing the activation energy required for a phase change, hence enhancing nucleation. The formation of vapour bubbles close to solid, ideally flat, walls is addressed here by exploiting a mesoscale description that couples diffuse interface modelling of the two-phase vapour-liquid system with fluctuating hydrodynamics, extending previous work by the authors on homogeneous nucleation.

Laser induced cavitation is one of the effective techniques to generate controlled cavitation bubbles, both for basic study and for applications
in different fields of engineering and medicine. Unfortunately, control of bubble formation and symmetry is hardly achieved due to
a series of concurrent causes. In particular, the need to focus the laser beam at the bubble formation spot leads, in general, to a conical
region proximal to the light source where conditions are met for plasma breakdown. A finite sized region then exists where the electric