Flow dynamics in cavitation induced micro pumping

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science Pub Date : 2025-06-04 DOI:10.1016/j.expthermflusci.2025.111540

V. Agrež, J. Zevnik, Ž. Lokar, M. Dular, R. Petkovšek

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Abstract

The micro pumping process driven by the laser induced cavitation bubbles is scalable, requires only optical access and does not require mechanical moving parts. We investigate how the positioning of the cavitation bubble affects the flow dynamics through differently sized holes in a transparent boundary mimicking a microchannel. For normalized standoff distance above 0.8 and normalized hole radius of 0.22 a significant flow through a hole was observed while decreasing the standoff distance a focused reverse flow was formed impeding downward pumping flow. The details of reverse flow formation were investigated. It was found that bubbles generated next to larger holes with a normalized radius of 0.66 also produce reverse flow, however without it impeding the flow through the structure, even at small normalized standoff distances. Simulations were found to agree well with experiments and used to further study the pumping behavior. Indentation on the bottom side of the bubble was found to be the driver of the focused reverse flow in simulations and differences were investigated for various hole radii and standoff distances. For larger hole radii, reverse flow was found to be both weaker and failed to block the entire hole width, permitting pumping behavior. To improve the flow in the pumping direction, additional structures were produced on top of the flat plate with holes. It was found that adding the entry structure to the hole mitigated the effect of the focused reverse flow on the pumping action.

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空化诱导微泵的流动动力学

由激光诱导的空化气泡驱动的微泵浦过程是可扩展的，只需要光学通道，不需要机械运动部件。我们研究了在模拟微通道的透明边界上，空化气泡的位置如何影响通过不同大小孔的流动动力学。当归一化距大于0.8、归一化孔半径为0.22时，孔内流动明显，当归一化距减小时，形成集中的反向流动，阻碍泵送向下流动。研究了反流形成的细节。研究发现，在归一化半径为0.66的较大孔附近产生的气泡也会产生逆流，但即使在较小的归一化距离处，气泡也不会阻碍流过结构。模拟结果与实验结果吻合较好，可用于进一步研究泵送行为。在模拟中发现气泡底部的压痕是聚焦逆流的驱动因素，并研究了不同孔半径和距离的差异。当井眼半径较大时，逆向流动较弱，无法阻塞整个井眼宽度，从而允许泵送行为。为了改善泵送方向的流动，在带孔的平板顶部增加了额外的结构。研究发现，在井眼中加入入口结构可以减轻聚焦逆流对泵送作用的影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experimental Thermal and Fluid Science 工程技术-工程：机械

CiteScore

6.70

自引率

3.10%

发文量

159

审稿时长

34 days

期刊介绍： Experimental Thermal and Fluid Science provides a forum for research emphasizing experimental work that enhances fundamental understanding of heat transfer, thermodynamics, and fluid mechanics. In addition to the principal areas of research, the journal covers research results in related fields, including combined heat and mass transfer, flows with phase transition, micro- and nano-scale systems, multiphase flow, combustion, radiative transfer, porous media, cryogenics, turbulence, and novel experimental techniques.