Nonlinear mechanics of fluidization of beds of spherical particles
Nonlinear mechanics of fluidization of beds of spherical particles
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DOI：
10.1017/s0022112087001046
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发表时间：
1987-04
影响因子：
3.7
通讯作者：
A. Fortes;D. Joseph;T. Lundgren
中科院分区：
文献类型：
--
作者：
A. Fortes;D. Joseph;T. Lundgren
描述了在矩形横截面的柱中克服重力落下的球形颗粒与水的流化实验。所有这些都受到与尾流相关的惯性效应的支配。涉及两种局部机制：起草、接吻和翻滚成稳定的跨流阵列。牵伸、接吻和翻滚都是重新排列机制，其中一个球体在另一个球体之后被捕获。接吻球与溪流对齐。流向排列非常不稳定，并且接吻球体会翻滚成更稳定的跨流双峰对，这些双峰对可以聚集成更大的相对稳定的水平阵列。受限于二维移动的球体床中的交叉流阵列是引人注目的。这些阵列甚至可能合并成被清水区域隔开的紧密堆积的球体聚集体。在正方形横截面的床中发现了上升球体的横流阵列的协作运动的较弱形式，其中球体可以在三个维度上自由移动。由于阻力较大，水平阵列在牵伸球下降的地方上升。球体的聚集似乎与水平球体阵列在其自身尾迹中上升的相对稳定的协作运动有关。
Experiments on fluidization with water of spherical particles falling against gravity in columns of rectangular cross-section are described. All of them are dominated by inertial effects associated with wakes. Two local mechanisms are involved: drafting and kissing and tumbling into stable cross-stream arrays. Drafting, kissing and tumbling are rearrangement mechanisms in which one sphere is captured in the wake of the other. The kissing spheres are aligned with the stream. The streamwise alignment is massively unstable and the kissing spheres tumble into more stable cross-stream pairs of doublets which can aggregate into larger relatively stable horizontal arrays. Cross-stream arrays in beds of spheres constrained to move in two dimensions are remarkable. These arrays may even coalesce into aggregations of close-packed spheres separated by regions of clear water. A somewhat weaker form of cooperative motion of cross-stream arrays of rising spheres is found in beds of square cross-section where the spheres may move freely in three dimensions. Horizontal arrays rise where drafting spheres fall because of greater drag. Aggregation of spheres seems to be associated with relatively stable cooperative motions of horizontal arrays of spheres rising in their own wakes.