Particulate matter exhibits emergent mechanical properties that play central roles in many physical and biological systems. The bulk response of particulate matter has contributions from thermal fluctuations and geometric exclusion, but little is known about the interplay between the two aspects. To probe this regime, together with Robert Riehn, we have developed a novel in-situ technique for assembling flow-stabilized solids by hydrodynamically confining particles from a dilute Brownian suspension. Intriguingly, we find these solids assemble in heap-like shapes and we find their mechanical properties can be described as a solid-like elastic material.
Carlos P. Ortiz, Robert Riehn, and Karen E. Daniels. Flow-driven formation of solid-like microsphere heaps. Soft Matter, 2013,9, 543-549