Department of Chemical Engineering, Swansea University, Swansea, SA1 8EN, UK.
PoreLab, Njord Center, Department of Physics, University of Oslo, N-0371, Oslo, Norway.
Nat Commun. 2023 May 26;14(1):3044. doi: 10.1038/s41467-023-38648-6.
Multiphase flows involving granular materials are complex and prone to pattern formation caused by competing mechanical and hydrodynamic interactions. Here we study the interplay between granular bulldozing and the stabilising effect of viscous pressure gradients in the invading fluid. Injection of aqueous solutions into layers of dry, hydrophobic grains represent a viscously stable scenario where we observe a transition from growth of a single frictional finger to simultaneous growth of multiple fingers as viscous forces are increased. The pattern is made more compact by the internal viscous pressure gradient, ultimately resulting in a fully stabilised front of frictional fingers advancing as a radial spoke pattern.
多相流涉及颗粒材料，由于机械和流体动力相互作用的竞争，容易形成模式。在这里，我们研究了颗粒推土作用与侵入流体粘性压力梯度稳定作用之间的相互作用。将水溶液注入干燥的疏水性颗粒层代表了一种粘性稳定的情况，随着粘性力的增加，我们观察到从单个摩擦指的生长到多个指同时生长的转变。内部粘性压力梯度使图案更加紧凑，最终导致作为辐射状轮辐图案前进的摩擦指的完全稳定前缘。
