A high rate flow-focusing foam generator

Dry microfoams: Formation and flow in a confined channel

We present an experimental investigation of the agglomeration of microbubbles into a 2D microfoam and its flow in a rectangular microchannel. Using a flow-focusing method, we produce the foam in situ on a microfluidic chip for a large range of liquid fractions, down to a few percent in liquid. We can monitor the transition from separated bubbles to the desired microfoam, in which bubbles are closely packed and separated by thin films. We find that bubble formation frequency is limited by the liquid flow rate, whatever the gas pressure. The formation frequency creates a modulation of the foam f…

Raydrop : a universal droplet generator based on a non-embedded co-flow-focusing

Most commercial microfluidic droplet generators rely on the planar flow-focusing configuration implemented in polymer or glass chips. The planar geometry, however, suffers from many limitations and drawbacks, such as the need of specific coatings or the use of dedicated surfactants, depending on the fluids in play. On the contrary, and thanks to their axisymmetric geometry, glass capillary-based droplet generators are a priori not fluid-dependent. Nevertheless, they have never reached the market because their assembly requires art-dependent and not scalable fabrication techniques. Here we pres…

Highly Viscous Microjet Generator

This paper describes a simple yet novel system for generating a highly viscous microjet. The jet is produced inside a wettable thin tube partially submerged in a liquid. The gas-liquid interface inside the tube, which is initially concave, is kept much deeper than that outside the tube. An impulsive force applied at the bottom of a liquid container leads to significant acceleration of the liquid inside the tube followed by flow-focusing due to the concave interface. The jet generation process can be divided into two parts that occur in different time scales, i.e. the Impact time (impact durati…

多孔弹性涡流发生器的高保真流固耦合仿真

High-Fidelity Fluid-Structure Interaction Simulations of Perforated Elastic Vortex Generators

本研究通过高保真双向耦合流固耦合仿真，探讨了开放通道中多孔弹性涡流发生器在多参数下的响应，发现其表现出静态、附着及涡激振动模式，且涡激振动由第二固有频率的锁定现象触发。