Abstract
The importance of surface topology for the generation of cavitating flows in micro scale has been emphasized during the last decade. In this regard, the utilization of surface roughness elements is not only beneficial in promoting mass transportation mechanisms, but also in improving the surface characteristics by offering new interacting surface areas. Therefore, it is possible to increase the performance of microfluidic systems involving multiphase flows via modifying the surface. In this study, we aim to enhance generation and intensification of cavitating flows inside microfluidic devices by developing artificial roughness elements and trapping hydrophobic fluorinated lubricants. For this, we employed different microfluidic devices with various hydraulic diameters, while roughness structures with different lengths were formed on the side walls of microchannel configurations. The surface roughness of these devices was developed by assembling various sizes of silica nanoparticles using the layer-by-layer technique (D2). In addition, to compare the cavitating flow intensity with regular devices having plain surfaces (D1), highly fluorinated oil was trapped within the pores of the existing thin films in the configuration D2 via providing the Slippery Liquid-Infused Porous Surface (D3). The microfluidic devices housing the short microchannel and the extended channel were exposed to upstream pressures varying from 1 to 7.23 MPa. Cavitation inception and supercavitation condition occured at much lower upstream pressures for the configurations of D2 and D3. Interestingly, hydraulic flip, which rarely appears in the conventional conical nozzles at high pressures, was observed at moderate upstream pressures for the configuration D2 proving the air passage existence along one side of the channel wall.
Highlights
Hydrodynamic cavitation in microscale as an emerging topic in the field of small bubble generation has attracted considerable attention in the engineering, energy and biomedical communities
This study reveals the potential of combined roughened surfaces and SLIPS in generating cavitating flows, which bolsters the idea of facile cavitating flow patterns in micro scale even at low pressure drops
SLIPS is presented as an effective method for earlier generation of cavitating flows, which is essential to decrease the input energy and increase the efficiency in microfluidic devices utilizing bubble clouds
Summary
Hydrodynamic cavitation in microscale as an emerging topic in the field of small bubble generation has attracted considerable attention in the engineering, energy and biomedical communities. This phenomenon can be manipulated by surface modifications in such a way that more intense cavity clouds could be generated. Layer-by-layer (LbL) assembly as an emerging technique has attracted the interest of many scientists for achieving different substrates regarding the surface roughness[4,5,6]. The studies related to the surface roughness effect on bubble dynamics mostly focused on bubble separation and mass transportation In this regard, SLIPS, hydrophobic and superhydrophobic surfaces have been considered by scientists in trapping, separating and transporting air bubbles under water. In the light of the studies on cavitation in microscale, the recent investigations deal with the surface configurations such as roughness implementations and embedded pillars inside a microchannel[19] to generate intensified cavitating flows
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
