The Effect of Shape on the Motion and Stability of Marangoni Surfers
The Effect of Shape on the Motion and Stability of Marangoni Surfers
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DOI：
10.1115/1.4048139
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发表时间：
2020
影响因子：
2
通讯作者：
S. Sur;Nicholas Uvanovic;Hassan Masoud;J. Rothstein
中科院分区：
文献类型：
--
作者：
S. Sur;Nicholas Uvanovic;Hassan Masoud;J. Rothstein
为了研究中等雷诺数下颗粒形状对其运动和稳定性的影响，研究了悬浮在空气-水界面上的球体和椭圆圆盘的Marangoni推进。马兰戈尼冲浪者的自我推进是通过在一半的球体和椭圆盘上涂上肥皂或异丙醇溶液来实现的。皂或异丙醇的存在导致在颗粒上的表面张力梯度，其在增加表面张力的方向上推动颗粒。超过临界速度，观察到从直线运动到旋转运动的过渡。观察到这些涡流在临界雷诺数以上脱落，导致不平衡扭矩，导致颗粒旋转。增加椭圆盘的长轴和短轴之间的纵横比被发现会降低它们的稳定性，并大大提高它们的旋转速率。对于沿平行于其长轴的方向运动的椭圆盘来说尤其如此。研究了粒子与培养皿壁的相互作用。发现排斥性的凹曲率降低稳定性并增强旋转运动，而吸引性的凸曲率则稳定球体的直线运动。对于中性浮力椭圆盘，边界壁的存在下，发现大大稳定的椭圆盘的直线运动时，他们在平行于他们的短轴的方向上行驶。由艾德主编的《流体工程杂志》发表。投稿日期：2020年2月18日;接受稿件日期：2020年8月18日。doi：10.1115/1.4048139 Copyright（c）2020 by ASME D ow naded rom ht：//asm edigitallection.asm e.org/fluidsengineering/art.1115/1.4048139/6558359/fe-20-1114.pdf by U niersity O f M asshuscott，Am hrst user on 02 O cber 2020
The Marangoni propulsion of spheres and elliptical disks floating on the air-water interface were studied to understand the effect of particle shape on its motion and its stability at moderate Reynolds numbers. Self-propulsion of the Marangoni surfer was achieved by coating half of the spheres and the elliptical disks with either a solution of soap or isopropyl alcohol. The presence of the soap or isopropyl alcohol resulted in a surface tension gradient across the particles which propelled the particles in the direction of increasing surface tension. Beyond a critical velocity, a transition was observed from a straightline motion to a rotational motion. These vortices were observed to shed above a critical Reynolds number resulting in an unbalanced torque that caused the particles to rotate. Increasing the aspect ratio between the major and minor axes of the elliptical disks was found to decrease their stability and greatly enhance their rate of rotation. This was especially true for elliptical disks traveling in a direction parallel to their major axis. The interactions between the particles and the wall of a Petri dish were also studied. Repulsive, concave curvature was found to decrease stability and enhance rotational motion, while attractive, convex curvature was shown to stabilize the straight-line motion of the spheres. For the neutrally buoyant elliptical disks, the presence of the bounding wall was found to greatly stabilize the straight-line motion of the elliptical disks when they were traveling in a direction parallel to their minor axis. Ac ce pt ed M an us cr ip t N ot C op ye di te d Journal of Fluids Engineering. Received February 18, 2020; Accepted manuscript posted August 18, 2020. doi:10.1115/1.4048139 Copyright (c) 2020 by ASME D ow naded rom ht://asm edigitallection.asm e.org/fluidsengineering/art.1115/1.4048139/6558359/fe-20-1114.pdf by U niersity O f M asshusetts, Am hrst user on 02 O cber 2020