Effect of the kinematic viscosity on liquid flow hydrodynamics in vortex mixers

The effect of the kinematic viscosity of similar fluids on liquid flow hydrodynamics and the onset of the instability were investigated to acquire information on the mixing behavior of vortex mixers. To assess the influence of the kinematic viscosity, water and two glycerin aqueous solutions with varying weight percentages (25 wt % and 50 wt %) were used. The critical Reynolds number of the flow regime transitions was found using PLIF and PIV flow-field techniques. The liquid flow hydrodynamics and gas flow dynamics in the proposed vortex mixer geometry were compared, as well. It was observed that the kinematic viscosity has a linear relation with the critical Reynolds number; however, the coefficient is different for liquids and gases. Additionally, kinematic viscosity dictates the minimum Reynolds number where the fluids have a full turn inside the chamber. It was observed that fluids having higher kinematic viscosities have a full turn at lower Reynolds numbers, and the critical Reynolds number value decreases with increasing kinematic viscosity.