共查询到19条相似文献,搜索用时 156 毫秒
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信息技术的发展日新月异,智能手机的出现使得居家实验成为了现实.基于智能手机phyphox软件的声波干涉实验现象明显,且从定性和定量的角度辅助学生更好地理解波的干涉.此实验仪器简单,操作简易,有利于培养学生的自主探究能力. 相似文献
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基于传统导热系数的测量方法,将集成式温度传感器换为测温更加灵敏且能通过蓝牙与智能手机连接实现可视化测温的探针温度传感器,利用其配套软件导出实验数据至手机Excel并直接利用手机Excel拟合出“温度-时间”曲线,计算待测物体的导热系数.研究结果表明,与传统方法相比探针法测得的实验结果相对误差更小、不确定度也更小.利用智能手机外设传感器进行可视化测量,不仅可以扩充智能手机的物理测量范围,还可以发挥智能手机的计算功能,从而在一部手机上完成物理测量和数据处理的全过程,方便开展居家实验,为今后创新性实验研究开创新的思路. 相似文献
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在势流假设下, 考虑表面张力以及黏性修正, 建立自由液面在气泡破碎后全非线性运动的数值模型, 给出射流断裂和水滴撕裂的数值处理方法. 同时进行上浮气泡在自由液面破裂的实验研究, 数值解与实验值符合良好.为了研究自由液面在气泡破碎后的运动学机理和规律, 运用开发的程序研究了不同尺寸气泡破碎后的动态特性, 包括从气泡底部顶起的射流、射流断裂以及水滴分裂等复杂的物理现象, 总结了从射流上撕裂出的第一个水滴尺寸、撕裂时间以及最大射流速度的变化规律. 最后讨论了雷诺数与韦伯数对气泡破碎后自由液面运动的影响.
关键词:
气泡
自由液面
破碎
断裂 相似文献
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本文采用高速摄像仪对水滴和乙醇液滴撞击加热壁面后的蒸发过程进行了实验观测, 分析了液滴撞击加热壁面后的蒸发特性参数. 实验中, 两种液体初始温度均为20 ℃, 不锈钢壁面初始温度范围为68-126℃. 水滴初始直径为2.07 mm, 撞击壁面时Weber 数为2-44; 乙醇液滴初始直径为1.64 mm, Weber数为3-88. 结果表明, 液滴受到重力、表面张力及流动性的影响, 在蒸发过程的大部分时间内, 水滴高度持续降低而接触直径几乎不变; 蒸发后期, 液滴发生回缩, 水滴的接触直径、高度和接触角出现振荡现象. 乙醇液滴的接触角随时间的增加呈现先减小随后保持不变的趋势, 而接触直径和高度则持续减小, 直到液滴完全蒸发. 液滴蒸发总时长与液体物性和壁面温度有关, 随壁面温度的升高而减小, 与液滴撞击壁面时的Weber 数无关. 同时, 随着壁面温度的升高, 液滴显热部分占总换热量的比重增大, 显热部分能量不可忽略, 本文实验条件下得到水滴的平均热流密度为0.014-0.110 W·mm-2. 相似文献
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Deeder M. Aurongzeb 《Solid State Communications》2005,134(3):165-169
Effect of temperature and surface tension on surface during sedimentation is studied using atomic force microscopy. Effects of surface tension is incorporated by using ∼1 mm radius water droplets. Surface tension of water droplet directed the deposition of dissolved particles around the perimeter of the droplet; leaving almost hollow circle in the middle with light deposition due to the particles being close to the surface. Evaporating shallow water solutions left random salt structures on the surface. Growth exponents are calculated along with the fractal dimension. For sedimentation process in shallow water (depth of ∼2 mm), a transition is observed from continuum model (1.88±0.2) to KPZ (0.406±0.082) universality class around ∼1 μm at room temperature. For droplets evaporation, turbulent (multi-affine) to self-affine transition is observed. Fractal dimensions (FD) for the droplets are found to be between one and two. The FD values are consistent with the fact that competing nonlinear terms are present in the system. 相似文献
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Alexander Karl Klaus Anders Martin Rieber Arnold Frohn 《Particle & Particle Systems Characterization》1996,13(3):186-191
Measurements of droplet deformation during wall impingement were performed for ethanol droplets and water droplets with diameters ranging from 100 to 200 μm. The wall temperature is well above the Leidenfrost temperature of the droplet liquid. With monodisperse droplet streams and a special illumination technique, slow motion images of the phenomena can be obtained. Measurements with high temporal resolution below 1 μs are possible using a standard video camera. The experimental results are compared with numerical results, which were obtained by solving the three-dimensional Navier-Stokes equations for incompressible fluids including surface tension effects. The fluids are treated with the volume-of-fluid method and the free surface is modeled according to the continuum-surface-force model. Numerical and experimental results show good agreement. 相似文献
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A simple model for size-dependent surface tension of liquid binary alloy droplets has been established based on Bulter’s equation and our model for size-dependent surface tension of pure liquid component. As an example, the surface tension of liquid Bi–Sn alloy droplets are calculated and discussed. The results show that as the size of the liquid alloy droplets decreases, the corresponding surface tension decreases. The component with lower surface tension is enriched in the surface layer at all times while relatively more another component with higher surface tension appear in the surface region when the size decreases. The effect of decreasing size on liquid alloy surface tension is like that of increasing temperature. When size is larger than about 12 nm, the size effect is small and negligible. 相似文献
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采用相界面跟踪(V()F)数值模拟方法,研究了轴流型微流控芯片中流速比、界面张力、粘度等对乳液粒子粒径的影响。模拟结果表明:乳液粒子粒径与流速比的对数存在线性关系,在一定范围内,当流速比增大时,粒径变小;当界面张力小于0.025 N/m时,乳液粒径随界面张力增大而增加,当界面张力超过0.03N/m时,乳液粒径变化趋于平缓;分散相粘度对乳液粒径的影响甚微。以聚乙烯醇(PVA)水溶液为连续相,二乙烯基苯(DVB)溶液为分散相,采用自制的聚二甲基硅氧烷(PDMS)轴流型微流控芯进行了DVB乳液粒子成型实验研究,获得了0.5~3.0 mm的DVB乳液粒子。 相似文献
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S. Masuda S. Sawada 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(3):637-644
We investigate the size-effect on the surface tension of nano-scale
gallium droplets by molecular dynamics simulations. The interaction
among gallium metal atoms is described by a many-body potential.
We derive a generic expression of the stress tensor to evaluate the
surface tension of systems including many-body interactions.
The equivalency between the mechanical and thermodynamic definitions
of the surface tension is also proved in such systems. It is shown
that the surface tension of gallium droplets increases with the droplet
size approaching its value for a planar surface, which is consistent
with the resent experimental result. 相似文献
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为研究液滴碰撞Janus颗粒(双亲性)球表面的独特行为特征,以粒径为5.0 mm铜球为材料制备了Janus颗粒,用直径为2.0 mm的液滴,在韦伯数(We)为2.7,10,20,30的测试情况下对Janus颗粒球表面进行了碰撞实验.结果表明:液滴碰撞Janus颗粒球表面后的运动可分为铺展、回缩、振荡和回弹4个过程.在不同We下,液滴碰撞Janus颗粒后的运动状态主要与表面润湿性相关,在Janus颗粒亲水侧表现为铺展特性且铺展系数γ随着时间t的增大而逐渐增大并趋于稳定;但在疏水侧,表现为回弹现象,铺展系数γ会出现类似"抛物线"形状;当液滴碰撞Janus颗粒球表面亲-疏水分界线时,液滴铺展和回弹同时发生.基于能量平衡和受力分析发现,液滴动能和表面能的互相转化是液滴铺展的关键,液滴会在重力、惯性力、表面张力、黏性力、接触力等力的综合作用下展现其独特的行为特征并最终达到平衡状态. 相似文献
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在实际的声操控中,由于声辐射力、表面张力和重力的共同作用,液滴往往呈现出椭球的形状,在螺旋声场中会受到力矩的作用而发生转动。从声波的散射理论出发,根据部分波展开法求解得到了椭球形液滴在Bessel驻波场中的声散射系数,并给出了其受到的声辐射转矩的解析式。在此基础上,对椭球形不可压缩液滴和椭球形可压缩液滴分别进行数值计算。仿真结果表明,不可压缩液滴的声辐射转矩与声束半锥角的关系更密切,而可压缩液滴则更依赖于特定的频率;提升Bessel驻波场的阶数有利于增强声辐射转矩的峰值,但在中低频处较难对可压缩液滴产生明显的力矩。该研究结果预期对利用螺旋声场进行液滴的操控具有理论指导作用。 相似文献
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A new method for the determination of surface tension from molecular dynamics simulations applied to liquid droplets
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For the determination of surface tension of liquid droplets by molecular dynamics simulations, the most time-consuming part is the calculation of pressure tensor in the transition layer, which makes it difficult to enhance the precision of the computation. A new method for the calculation of surface tension of liquid droplets to reduce the calculation quantity of pressure tensor in transition layer to the minimum is proposed in this paper. Two thousand particles are taken as example to show how to carry out our scheme. 相似文献