We have performed numerical simulations to investigate the phenomenon of axial pattern formation exhibited by a non-neutrally buoyant concentrated suspension. Continuum modelling of the concentrated suspension is done using the suspension balance model to identify the underlying mechanism of the phenomenon. We demonstrate that axial concentration variations become amplified to axial bands owing to the influence of the second normal stress difference ( $N_2$ ), and the first normal difference ( $N_1$ ) accentuates the effect of $N_2$ . We demonstrate that the end walls of the rotating cylinder are necessary to prevent the smearing out of axial bands but are not a direct cause of the phenomenon.

中文翻译：

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水平旋转筒内浓缩悬浮液轴向图案形成机理

我们进行了数值模拟来研究非中性浮力浓缩悬浮液所表现出的轴向图案形成现象。使用悬浮液平衡模型对浓缩悬浮液进行连续体建模，以确定该现象的潜在机制。我们证明，由于第二法向应力差的影响，轴向浓度变化被放大到轴向带（ $N_2$ ) 和第一个正态差分 ( $N_1$ ) 强调了效果 $N_2$ 。我们证明，旋转圆柱体的端壁对于防止轴向带的涂抹是必要的，但并不是造成这种现象的直接原因。