Streaming-enhanced flow-mediated transport

Abstract

We investigate the capability of an active body (master) to manipulate a passive object (slave) purely via contactless flow-mediated mechanisms, motivated by potential applications in microfluidic devices and medicine (drug delivery purposes). We extend prior works on active-passive cylinder pairs by superimposing periodic oscillations to the master's linear motion. In a viscous fluid, such oscillations produce an additional viscous streaming field, which is leveraged for enhancing slave transport. We see that superimposing oscillations robustly improves transport across a range of Reynolds numbers. Comparison with results without oscillations highlights the flow mechanisms at work, which we capitalize on to design (master) geometries for augmented transport. These principles are found to extend to three-dimensional active-passive shapes as well. * Electronic address: mgazzola@illinois.edu arXiv:1809.04566v1 [physics.flu-dyn]

Shape curvature effects in viscous streaming

“…We analyse the different flow topologies that arise as we vary the cylinders' curvature ratios and the frequency of the background oscillatory flow, and characterize their transitions via bifurcation theory. Finally, we demonstrate that our understanding can be extended to generalized, individual bodies, aided by comparison against prior experiments (Tatsuno 1974(Tatsuno , 1975) and computations (Parthasarathy et al 2019). Overall, this study elucidates the mechanisms at play when streaming flow topology is manipulated via regulated variations of shape geometry, thus providing a rational design approach and physical intuition.…”

“…This method has been validated across a range of flow-structure interaction problems, from flow past bluff bodies to biological swimming (Gazzola et al 2011(Gazzola et al , 2012aGazzola, Van Rees & Koumoutsakos 2012b;Gazzola, Hejazialhosseini & Koumoutsakos 2014;Gazzola et al 2016). Recently, it has also been shown to effectively capture spatio-temporal scales related to viscous streaming (Parthasarathy et al 2019).…”

“…In a recent study, we illustrated how a 'bullet' shaped streaming bot enhances fluid mediated transport of passive particles relative to simple circular cylinders (Parthasarathy et al 2019). The bullet geometry was empirically determined based on experiments on triangles (Tatsuno 1975), from which we borrowed fore-aft asymmetry and high rear curvature profiles.…”

“…Indeed, these bots operate across flow regimes where streaming effects can be important, and may be usefully leveraged, opening new opportunities for micro-robotics in manufacturing or medicine (Ceylan et al 2017). For example, in a recent study (Parthasarathy, Chan & Gazzola 2019), we showed that streaming can enhance the contactless transport of passive inertial particles (drug payload) by moving cylindrical mini-bots. There, we also highlighted that morphing a circular cylinder to a suitably sculpted shape that combines asymmetry and high rear curvature, can further improve transport.…”

The impact of steady streaming and conditional turbulence on gas transport during high-frequency ventilation

“…This turbulence is also likely to be triggered by the ribbed structure of the tracheal wall providing a flow disturbance at the pipe wall [ 50 ]. Due to the presence of sharp curvatures, the ribbed structures may potentially generate streaming fields that are non-trivial in the above scales of gas transport [ 5 , 38 ]. The presence of such ribbings in the upper airway might cause potential mechanisms of the gas transport in the HFV; however is beyond the scope of this study.…”