Flow and Final Shapes of Printed Yild Stress Filaments

Various coating, inkjet printing, and 3D printing techniques utilize the deposition of droplets and filaments of yield stress fluids on a substrate. On small scales, surface tension is the primary driving mechanism, determining the dynamics and the final shape of the deposited material. We present experimental and theoretical results within the plastocapillarity limit, where the competition between surface tension and the complex elasto-viscoplastic rheology of the material determines the dynamics of spreading and the final shape of the deposition. To this end, we analyze single filaments and the coalescence of two filaments on the surface.