Modelling viscous boundary layer dissipation effects in liquid surrounding individual solid nano and micro-particles in an ultrasonic field.
Modelling viscous boundary layer dissipation effects in liquid surrounding individual solid nano and micro-particles in an ultrasonic field.
复制标题
模拟超声波场中单个固体纳米和微米颗粒周围液体的粘性边界层耗散效应。
DOI：
10.1038/s41598-019-40665-9
复制
发表时间：
2019
影响因子：
4.6
通讯作者：
Forrester DM
中科院分区：
文献类型：
--
作者：
Forrester DM
当将超声波应用于液体中固体颗粒的悬浮液时，在颗粒/液体界面处发生多重散射，导致衰减。最近通过实验验证表明，当散射体的浓度甚至低至几个体积百分比时，多重散射理论必须包括纳米流体中的液体和固体颗粒之间的边界处的剪切波影响。在这里，我们考虑在长波长范围内的直径为50-450 nm的二氧化硅球，以阐明单个颗粒在液/固界面处的剪切衰减场的形式。这是重要的，因为这些场的重叠最终导致压缩波到剪切波的转换，并返回到压缩波，该效果源于颗粒和液体之间的密度对比。因此，我们详细研究的速度，涡度和粘性耗散的剪切波场和周围的二氧化硅球使用有限元建模，清晰的粘性边界效应。我们还比较了半解析结果的数值模拟。
Upon application of ultrasonic waves to a suspension of solid particles in liquid, multiple scattering occurs at the particle/liquid interfaces leading to attenuation. It was recently shown through experimental verification that multiple scattering theory must include shear wave influences at the boundary between the liquid and solid particles in a nanofluid when the concentration of the scatterers is even as low as a few percent by volume. Herein, we consider silica spheres of 50–450 nm diameter in the long-wavelength regime to elucidate the form of the shear decay fields at the liquid/solid interface for individual particles. This is important because the overlap of these fields ultimately leads to the conversion of a compressional wave to shear waves and back into the compressional wave, the effect originating due to the density contrast between the particle and the liquid. Therefore, we examine in detail the velocity, vorticity and viscous dissipation in the shear wave field and around the silica spheres using finite element modelling, giving clarity to the viscous boundary effects. We also compare the numerical modelling to semi-analytical results.