Increase of turbulent drag by polymers in particle suspensions
Increase of turbulent drag by polymers in particle suspensions
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DOI：
10.1103/physrevfluids.5.041301
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发表时间：
2020-04-07
影响因子：
2.7
通讯作者：
Brandt, Luca
中科院分区：
文献类型：
--
作者：
Rosti, Marco Edoardo;Brandt, Luca
我们研究了球形颗粒对粘弹性流体湍流流动的影响，发现聚合物添加剂的减阻效果在半稠密悬浮液中完全丧失，其阻力比在牛顿流体中的悬浮液增加更多。这种不同的行为是由于三个独立的影响。首先，刚性颗粒的存在降低了聚合物拉伸，因此抵消了粘弹性流体的减阻益处。第二，由于颗粒表面附近较大的剪切速率，颗粒的生长和颗粒的聚合物剪切应力提供了阻力增加。第三，由于流体的剪切稀化特性，颗粒向壁迁移，从而增强颗粒近壁层并进一步增加阻力。
We study the effect of spherical particles on the turbulent flow of a viscoelastic fluid and find that the drag reducing effect of polymer additives is completely lost for semidense suspensions, with the drag increasing more than for suspensions in Newtonian fluids. This different behavior is due to three separate effects. First, polymer stretching is reduced by the presence of rigid particles, thus canceling the drag reducing benefit of the viscoelastic fluid. Second, drag increase is provided by the growth of the particle and polymeric shear stresses with the particles, due to larger shear rates in the vicinity of the particle surface. Third, particles migrate towards the wall due to the shear-thinning property of the fluid, thus enhancing the particle near-wall layer and further increasing the drag.