Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental study
Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental study
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弹粘塑性流体方形管道流中的有限尺寸球形颗粒：实验研究
DOI：
10.1017/jfm.2019.868
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发表时间：
2019
影响因子：
3.7
通讯作者：
L. Brandt
中科院分区：
文献类型：
--
作者：
S. Zade;Tafadzwa John Shamu;F. Lundell;L. Brandt
本实验研究解决了具有一定弹性的屈服应力流体（卡波普凝胶）在方形管道中的流动。在多雷诺数Re^{\ast }\in$（1，200）和宾汉数Bi\in$（0.01，0.35）条件下，研究了屈服应力较低和较高的两种流体的摩擦系数和流速。利用二维粒子图像测速（PIV）技术，利用正方形管道中的对称面，重建了整个三分量速度场。观察到由八个涡流组成的二次流使流体从核心向壁中心再循环，并从拐角返回核心。这些涡的范围和强度的增长与增加$Re^{\ast }$，或者，作为替代，作为塞尺寸减小。本研究的第二个目的是探索在颗粒存在下的流动变化。为此，几乎中性浮力有限大小的球形颗粒的管道高度，$2H$，颗粒直径，$d_{p}$，比例为12，在两个体积分数$\unicode[STIX]{x1 D 719}=5$和10%。粒子跟踪测速仪用于测量透明Carbopol凝胶中这些折射率匹配的球体的速度，PIV用于提取流体速度。此外，简单的阴影也被用来定性可视化的颗粒分布沿着流向的发展。颗粒分布模式从在低流速下集中在四个角处改变为在高流速下沿着中心和角之间的扩散环集中。颗粒的存在会引起流体相的流向和壁面法向速度波动;然而，与湍流相比，主雷诺切应力仍然非常小。在颗粒负载的情况下，塞的大小似乎是小于相应的单相情况下。与牛顿流体类似，由于颗粒的存在，摩擦系数增加，几乎与悬浮流体基质无关。有趣的是，预测的基础上增加的有效悬浮液粘度同意相当好的实验摩擦系数的浓度在这项研究中使用。
The present experimental study addresses the flow of a yield stress fluid with some elasticity (Carbopol gel) in a square duct. The behaviour of two fluids with lower and higher yield stress is investigated in terms of the friction factor and flow velocities at multiple Reynolds numbers $Re^{\ast }\in$ (1, 200) and, hence, Bingham numbers $Bi\in$ (0.01, 0.35). Taking advantage of the symmetry planes in a square duct, we reconstruct the entire 3-component velocity field from two-dimensional particle image velocimetry (PIV). A secondary flow consisting of eight vortices is observed to recirculate the fluid from the core towards the wall centre and from the corners back to the core. The extent and intensity of these vortices grows with increasing $Re^{\ast }$ or, alternately, as the plug size decreases. The second objective of this study is to explore the change in flow in the presence of particles. To this end, almost neutrally buoyant finite-size spherical particles with a duct height, $2H$, to particle diameter, $d_{p}$, ratio of 12 are used at two volume fractions $\unicode[STIX]{x1D719}=5$ and 10 %. Particle tracking velocimetry is used to measure the velocity of these refractive-index-matched spheres in the clear Carbopol gel, and PIV to extract the fluid velocity. Additionally, simple shadowgraphy is also used to qualitatively visualise the development of the particle distribution along the streamwise direction. The particle distribution pattern changes from being concentrated at the four corners, at low flow rates, to being focussed along a diffused ring between the centre and the corners, at high flow rates. The presence of particles induces streamwise and wall-normal velocity fluctuations in the fluid phase; however, the primary Reynolds shear stress is still very small compared to turbulent flows. The size of the plug in the particle-laden cases appears to be smaller than the corresponding single-phase cases. Similar to Newtonian fluids, the friction factor increases due to the presence of particles, almost independently of the suspending fluid matrix. Interestingly, predictions based on an increased effective suspension viscosity agrees quite well with the experimental friction factor for the concentrations used in this study.
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影响因子：
3.7
作者：
M. Rosti;D. Izbassarov;O. Tammisola;S. Hormozi;L. Brandt
通讯作者：
M. Rosti;D. Izbassarov;O. Tammisola;S. Hormozi;L. Brandt
影响因子：
3.1
作者：
Mohammadhossein Firouznia;B. Metzger;G. Ovarlez;S. Hormozi
通讯作者：
Mohammadhossein Firouznia;B. Metzger;G. Ovarlez;S. Hormozi
屈服应力流体压裂流中固体的分散
影响因子：
3.7
作者：
Hormozi, S.;Frigaard, I. A.
通讯作者：
Frigaard, I. A.
影响因子：
1.8
作者：
Izbassarov, Daulet;Rosti, Marco E.;Tammisola, Outi
通讯作者：
Tammisola, Outi