当前位置：
X-MOL 学术
›
Soft Matter
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Inertio-capillary cross-streamline drift of droplets in Poiseuille flow using dissipative particle dynamics simulations
Soft Matter ( IF 2.9 ) Pub Date : 2018-02-26 00:00:00 , DOI: 10.1039/c7sm02294h Ryan L. Marson 1, 2, 3, 4 , Yuanding Huang 1, 2, 3, 4, 5 , Ming Huang 1, 2, 3, 4 , Taotao Fu 1, 2, 3, 4, 6 , Ronald G. Larson 1, 2, 3, 4
Soft Matter ( IF 2.9 ) Pub Date : 2018-02-26 00:00:00 , DOI: 10.1039/c7sm02294h Ryan L. Marson 1, 2, 3, 4 , Yuanding Huang 1, 2, 3, 4, 5 , Ming Huang 1, 2, 3, 4 , Taotao Fu 1, 2, 3, 4, 6 , Ronald G. Larson 1, 2, 3, 4
Affiliation
|
We find using dissipative particle dynamics (DPD) simulations that a deformable droplet sheared in a narrow microchannel migrates to steady-state position that depends upon the dimensionless particle capillary number 
, which controls the droplet deformability (with Vmax the centerline velocity, μf the fluid viscosity, Γ the surface tension, R the droplet radius, and H the gap), the droplet (particle) Reynolds number 
, which controls inertia, where ρ is the fluid density, as well as on the viscosity ratio of the droplet to the suspending fluid κ = μd/μf. We find that when the Ohnesorge number 
is around 0.06, so that inertia is stronger than capillarity, at small capillary number Cap < 0.1, the droplet migrates to a position close to that observed for hard spheres by Segre and Silberberg, around 60% of the distance from the centerline to the wall, while for increasing Cap the droplet steady-state position moves smoothly towards the centerline, reaching around 20% of the distance from centerline to the wall when Cap reaches 0.5 or so. For higher Oh, the droplet position is much less sensitive to Cap, and remains at around 30% of the distance from centerline to the wall over the whole accessible range of Cap. The results are insensitive to viscosity ratios from unity to the highest value studied here, around 13, and the drift towards the centerline for increasing Cap is observed for ratios of droplet diameter to gap size ranging from 0.1 to 0.3. We also find consistency between our predictions and existing perturbation theory for small droplet or particle size, as well as with experimental data. Additionally, we assess the accuracy of the DPD method and conclude that with current computer resources and methods DPD is not readily able to predict cross-stream-line drift for small particle Reynolds number (much less than unity), or for droplets that are less than one tenth the gap size, owing to excessive noise and inadequate numbers of DPD particles per droplet.
中文翻译：
使用耗散粒子动力学模拟的Poiseuille流动中液滴的惰性-毛细管跨流线漂移
我们发现使用耗散粒子动力学（DPD）模拟该可变形的微滴在狭窄的微通道迁移到稳定状态的立场，即取决于量纲粒子毛细管数剪切，其控制所述液滴变形（与V最大的中心线速度，μ ˚F的流体粘度，Γ是表面张力，R是液滴半径，H是间隙），液滴（颗粒）雷诺数，它控制惯性，其中ρ是流体密度，以及液滴与流体的粘度比悬浮流体κ = μ d / μf。我们发现，当Ohnesorge数约为0.06时，惯性比毛细管作用强，在较小的毛细管数Ca p <0.1时，液滴迁移到接近Segre和Silberberg观察到的硬球位置的位置，约为60％从中心线到壁的距离，而为了增加Ca p，液滴稳态位置向中心线平滑移动，当Ca p达到0.5左右时，达到从中心线到壁的距离的20％左右。对于更高的哦，液滴位置是多少钙不太敏感p，并用Ca的整个访问范围保持在30％左右，从中心线到壁的距离的p。结果对粘度比（从统一到最高）（在此处约为13）不敏感，并且在液滴直径与间隙尺寸的比值为0.1至0.3的情况下，观察到了向中心线漂移以增加Ca p。我们还发现，对于小液滴或颗粒大小的预测与现有微扰理论之间的一致性，以及与实验数据的一致性。此外，我们评估了DPD方法的准确性，并得出结论，使用当前的计算机资源和方法，DPD无法轻易预测小粒子雷诺数（远小于1）或液滴较小时的跨流线漂移。由于过大的噪音和每个液滴的DPD粒子数量不足，因此间隙尺寸不能超过间隙尺寸的十分之一。
更新日期：2018-02-26
, which controls the droplet deformability (with Vmax the centerline velocity, μf the fluid viscosity, Γ the surface tension, R the droplet radius, and H the gap), the droplet (particle) Reynolds number , which controls inertia, where ρ is the fluid density, as well as on the viscosity ratio of the droplet to the suspending fluid κ = μd/μf. We find that when the Ohnesorge number is around 0.06, so that inertia is stronger than capillarity, at small capillary number Cap < 0.1, the droplet migrates to a position close to that observed for hard spheres by Segre and Silberberg, around 60% of the distance from the centerline to the wall, while for increasing Cap the droplet steady-state position moves smoothly towards the centerline, reaching around 20% of the distance from centerline to the wall when Cap reaches 0.5 or so. For higher Oh, the droplet position is much less sensitive to Cap, and remains at around 30% of the distance from centerline to the wall over the whole accessible range of Cap. The results are insensitive to viscosity ratios from unity to the highest value studied here, around 13, and the drift towards the centerline for increasing Cap is observed for ratios of droplet diameter to gap size ranging from 0.1 to 0.3. We also find consistency between our predictions and existing perturbation theory for small droplet or particle size, as well as with experimental data. Additionally, we assess the accuracy of the DPD method and conclude that with current computer resources and methods DPD is not readily able to predict cross-stream-line drift for small particle Reynolds number (much less than unity), or for droplets that are less than one tenth the gap size, owing to excessive noise and inadequate numbers of DPD particles per droplet.
中文翻译：
使用耗散粒子动力学模拟的Poiseuille流动中液滴的惰性-毛细管跨流线漂移
我们发现使用耗散粒子动力学（DPD）模拟该可变形的微滴在狭窄的微通道迁移到稳定状态的立场，即取决于量纲粒子毛细管数剪切
，其控制所述液滴变形（与V最大的中心线速度，μ ˚F的流体粘度，Γ是表面张力，R是液滴半径，H是间隙），液滴（颗粒）雷诺数，它控制惯性，其中ρ是流体密度，以及液滴与流体的粘度比悬浮流体κ = μ d / μf。我们发现，当Ohnesorge数约为0.06时，惯性比毛细管作用强，在较小的毛细管数Ca p <0.1时，液滴迁移到接近Segre和Silberberg观察到的硬球位置的位置，约为60％从中心线到壁的距离，而为了增加Ca p，液滴稳态位置向中心线平滑移动，当Ca p达到0.5左右时，达到从中心线到壁的距离的20％左右。对于更高的哦，液滴位置是多少钙不太敏感p，并用Ca的整个访问范围保持在30％左右，从中心线到壁的距离的p。结果对粘度比（从统一到最高）（在此处约为13）不敏感，并且在液滴直径与间隙尺寸的比值为0.1至0.3的情况下，观察到了向中心线漂移以增加Ca p。我们还发现，对于小液滴或颗粒大小的预测与现有微扰理论之间的一致性，以及与实验数据的一致性。此外，我们评估了DPD方法的准确性，并得出结论，使用当前的计算机资源和方法，DPD无法轻易预测小粒子雷诺数（远小于1）或液滴较小时的跨流线漂移。由于过大的噪音和每个液滴的DPD粒子数量不足，因此间隙尺寸不能超过间隙尺寸的十分之一。
京公网安备 11010802027423号