We consider inertial focusing of particles in channels with triangular cross sections. The number and the location of inertial focusing positions in isosceles triangular channels can change with varying blockage ratios (a/H) and Reynolds numbers (Re). In triangular channels, asymmetric velocity gradient induced by the sloped sidewalls leads to changes in the direction and the strength of the inertial lift forces. Therefore, varying the configuration (specifically, angle) of the triangular cross section is expected to lead to a better understanding of the nature of the inertial lift forces. We fabricated triangular microchannels with various apex angles using channel molds that were shaped by a planing process, which provides precise apex angles and sharp corners. The focusing position shift was found to be affected by the channel cross section, as expected. It was determined that the direction of the focusing position shift can be reversed depending on whether the vertex is acute or obtuse. More interestingly, corner focusing modes and splitting of the corner focusing were observed with increasing Re, which could explain the origin of the inertial focusing position changes in triangular channels. We conducted fluid dynamic simulations to create force maps under various conditions. These force maps were analyzed to identify the basins of attraction of various attractors and pinpoint focusing locations using linear stability analysis. Calculating the relative sizes of the basins of attractions and exhaustively identifying the focusing positions, which are very difficult to investigate experimentally, provided us a better understanding of trends in the focusing mechanism.

中文翻译：

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在具有各种顶角的三角形微通道中进行惯性聚焦

我们考虑了具有三角形横截面的通道中粒子的惯性聚焦。等腰三角形通道中惯性聚焦位置的数量和位置可以随着阻塞率（a / H）和雷诺数（Re）。在三角形通道中，由倾斜侧壁引起的不对称速度梯度会导致惯性升力的方向和强度发生变化。因此，期望改变三角形横截面的构造（具体地，角度）可以导致对惯性升力的性质的更好的理解。我们使用通过平面加工成型的通道模具制造了具有各种顶角的三角形微通道，从而提供了精确的顶角和尖角。如预期的那样，发现聚焦位置偏移受通道横截面影响。确定了可以根据顶点是锐角还是钝角来反转聚焦位置移动的方向。更有趣的是Re，这可以解释三角形通道中惯性聚焦位置变化的起源。我们进行了流体动力学模拟，以创建各种条件下的力图。分析这些力图以使用线性稳定性分析来识别各种吸引子的吸引盆地和精确的聚焦位置。计算吸引盆的相对大小并详尽地确定聚焦位置，这很难通过实验进行研究，这使我们对聚焦机制的趋势有了更好的了解。