Yield-stress materials, which require a sufficiently large forcing to flow, are currently ill-understood theoretically. To gain insight into their yielding transition, we study numerically the rheology of a suspension of deformable droplets in 2D. We show that the suspension displays yield-stress behavior, with droplets remaining motionless below a critical body-force. In this phase, droplets jam to form an amorphous structure, whereas they order in the flowing phase. Yielding is linked to a percolation transition in the contacts of droplet-droplet overlaps and requires strict conservation of the droplet area to exist. Close to the transition, we find strong oscillations in the droplet motion that resemble those found experimentally in confined colloidal glasses. We show that even when droplets are static, the underlying solvent moves by permeation so that the viscosity of the composite system is never truly infinite, and its value ceases to be a bulk material property of the system.

中文翻译：

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可变形液滴悬浮液中的屈服应力转变

屈服应力材料需要足够大的力才能流动，目前在理论上尚不清楚。为了深入了解它们的屈服转变，我们对二维可变形液滴悬浮液的流变学进行了数值研究。我们表明，悬浮液表现出屈服应力行为，液滴在低于临界体积力时保持静止。在这个阶段，液滴堵塞形成无定形结构，而在流动阶段它们是有序的。屈服与液滴-液滴重叠接触处的渗滤转变有关，并且需要严格保护液滴区域才能存在。接近转变时，我们发现液滴运动中存在强烈的振荡，类似于在受限胶体玻璃中实验发现的振荡。我们表明，即使当液滴静止时，下面的溶剂也会通过渗透而移动，因此复合系统的粘度永远不会真正无限，并且其值不再是系统的散装材料属性。