Effects of non-Newtonian fluid on trapped vortices at T-junction*

A typical printing solution consists of multi-component materials. Thus, understanding hydrodynamic effect of complex printing solution in a pipe flow is important to design the printing system including a tubing, nozzle tip and channel branch. Particularly, for the multi-nozzle extrusion system, T-junction is a key element to split and control flow rates at each branch. It is recently reported that for Newtonian fluid, vortices are generated and trapped at Re ~ O(100). The recirculating flow is not favorable for multi-outlets because it is unstable and difficult to precisely control mass transport along the channel. In this study, we numerically study the effect of non-Newtonian fluid at the T-junction. We explore how the vortex develops and evolves at the T-junction where different types of non-Newtonian fluids are applied for instance shear-thinning, shear thickening, and viscoelastic fluid. In conclusion, we will provide design criteria for multi-outlet channels to establish the stable flow pattern.