When granular materials, colloidal suspensions, and even animals and crowds exit through a narrow outlet, clogs can form spontaneously when multiple particles or entities attempt to exit simultaneously, thereby obstructing the outlet and ultimately halting the flow. Counterintuitively, the presence of an obstacle upstream of the outlet has been found to suppress clog formation. For soft particles such as emulsion drops, clogging has not been observed in the fast flow limit due to their deformability and vanishing interparticle friction. Instead, they pinch off each other and undergo break up when multiple drops attempt to exit simultaneously. Similar to how an obstacle reduces clogging in a rigid particle system, we hypothesize and demonstrate that an obstacle could suppress break up in the two-dimensional hopper flow of a microfluidic crystal consisting of dense emulsion drops by preventing the simultaneous exit of multiple drops. A regime map plotting the fraction of drops that undergo break up in a channel with different obstacle sizes and locations delineates the geometrical constraints necessary for effective break up suppression. When optimally placed, the obstacle induced an unexpected ordering of the drops, causing them to alternate and exit the outlet one at a time. Droplet break up is suppressed drastically by almost three orders of magnitude compared to when the obstacle is absent. This result can provide a simple, passive strategy to prevent droplet break up and can find use in improving the robustness and integrity of droplet microfluidic biochemical assays as well as in extrusion-based three-dimensional printing of emulsion or foam-based materials.

当颗粒材料、胶体悬浮液，甚至动物和人群通过狭窄的出口离开时，当多个颗粒或实体试图同时离开时，会自发形成堵塞物，从而阻塞出口并最终停止流动。与直觉相反，已经发现出口上游存在障碍物可以抑制堵塞的形成。对于软颗粒，如乳液滴，由于它们的变形能力和消失的颗粒间摩擦，在快速流动极限中没有观察到堵塞。相反，当多个液滴试图同时退出时，它们会相互夹住并破裂。类似于障碍物如何减少刚性粒子系统中的堵塞，我们假设并证明了障碍物可以通过阻止多滴同时退出来抑制由致密乳液滴组成的微流体晶体的二维漏斗流的破裂。绘制在具有不同障碍物尺寸和位置的通道中破碎的液滴比例的状态图描绘了有效抑制破碎所需的几何约束。当放置在最佳位置时，障碍物会引起水滴的意外排序，导致它们交替并一次一个地离开出口。与没有障碍物时相比，液滴破裂被大大抑制了近三个数量级。这个结果可以提供一个简单的，