M71.00281. Drop breakup in yield stress fluids

Presented by: Juan Reimondo


We study the production of droplets inside yield stress fluids (YSFs) using an extrusion-based 3D printer device. Microgel-based YSFs have recently gained traction in 3D printing applications due to their ability to be molded when stresses are applied, followed by immediate solidification to hold shapes when stresses are removed. The capillary breakup of an immiscible Newtonian fluid inside a YSF can be eliminated completely when the yield stress of the YSF is sufficiently high. This contrasts with simple liquids, where the dispersed phase of co-flowing streams always breaks into spherical droplets. There is, however, and intermediate regime where the evolution of capillary breakup and shape relaxation of drops is arrested, resulting in droplets of non-spherical shapes. By carefully tuning the flow and shear parameters, we demonstrate precision control of dispersed drop shapes through simple physical parameters in ‘co-flowing’ streams of a Newtonian fluid and a surrounding YSF.


  • Juan Reimondo
  • Josefa Guerrero Millan
  • Ya-Wen Chang


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