Viscoelastic flow instabilities in static mixers: Onset and effect on the mixing efficiency

Elastic instabilities are identified as flow occurring in the presence of low inertial effects, induced by combination strong elastic forces with nonlinearities flow. In continuous laminar mixing applications, onset these is likely to occur window applied rates; therefore, it important understand effects their on process efficiency. this work, we investigated experimentally two tubular static mixers different geometric features, i.e., Kenics helical mixer and SMB-R mixer, latter characterized a double X-shaped bar geometry. We obtained concentration maps at various lengths means planar laser fluorescence techniques. To deduce generalized effect fluid elasticity patterns, tested three fluids rheological behavior—a Boger shear-thinning fluids. For all cases, observed deviations from Newtonian benchmark soon Deborah number exceeded unity, even though transitions occurred mean rate increased. The instability patterns strongly depended kinematics geometries: for typical lamellar structure not recovered liquid streams remain unmixed, while SMB-R, unsteady, showing temporally spatially chaotic fluctuations mass fraction. both worsen efficiency compared case.