Hopper flows of deformable particles
Hopper flows of deformable particles
复制标题
可变形颗粒的料斗流动
DOI：
10.1039/d2sm01079h
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发表时间：
2022
期刊：
影响因子：
3.4
通讯作者：
O'Hern, Corey S.
中科院分区：
文献类型：
--
作者：
Cheng, Yuxuan;Treado, John D.;Lonial, Benjamin F.;Habdas, Piotr;Weeks, Eric R.;Shattuck, Mark D.;O'Hern, Corey S.
大量的实验和计算研究表明，颗粒状物料的连续料斗流服从Beverloo方程，该方程将体积流量Q和孔口宽度w联系起来：Q <$（w/σavg − k）β，其中σavg是平均粒径，kσavg是偏移量，其中Q <$0，幂律标度指数β = d − 1/2，d是空间维度。近年来对不同背景流体中可变形颗粒漏斗流动的研究表明，颗粒的刚度和耗散机制也会强烈影响幂律标度指数β。我们进行了计算研究料斗流动的变形颗粒的动摩擦和背景流体耗散在二维和三维。结果表明，指数β随粘滞阻力与动摩擦系数之比λ = λ/μ连续变化。β = d − 1/2（λ → 0极限）和d − 3/2（λ → ∞极限），中点λc取决于料斗开口角θw。我们还描述了流动的空间结构，并将料斗流动的空间结构的变化与指数β的变化相关联。偏移量k随着颗粒刚度的增加而增加，直到k>硬颗粒极限中的kmax，其中λ → ∞时的kmax> 3.5，大于λ → 0时的kmax。最后，我们表明，在λ → ∞极限的可变形颗粒漏斗流的模拟概括了准二维油滴在水中漏斗流的实验结果。
Numerous experimental and computational studies show that continuous hopper flows of granular materials obey the Beverloo equation that relates the volume flow rate Q and the orifice width w: Q ∼ (w/σavg − k)β, where σavg is the average particle diameter, kσavg is an offset where Q ∼ 0, the power-law scaling exponent β = d − 1/2, and d is the spatial dimension. Recent studies of hopper flows of deformable particles in different background fluids suggest that the particle stiffness and dissipation mechanism can also strongly affect the power-law scaling exponent β. We carry out computational studies of hopper flows of deformable particles with both kinetic friction and background fluid dissipation in two and three dimensions. We show that the exponent β varies continuously with the ratio of the viscous drag to the kinetic friction coefficient, λ = ζ/μ. β = d − 1/2 in the λ → 0 limit and d − 3/2 in the λ → ∞ limit, with a midpoint λc that depends on the hopper opening angle θw. We also characterize the spatial structure of the flows and associate changes in spatial structure of the hopper flows to changes in the exponent β. The offset k increases with particle stiffness until k ∼ kmax in the hard-particle limit, where kmax ∼ 3.5 is larger for λ → ∞ compared to that for λ → 0. Finally, we show that the simulations of hopper flows of deformable particles in the λ → ∞ limit recapitulate the experimental results for quasi-2D hopper flows of oil droplets in water.