Abstract Summary (Max 250 words)
Applications of CFD to stirred tanks in the laminar and turbulent regimes are ubiquitous, yet many tanks used for the manufacture of formulated liquid consumer products of complex and/or evolving rheology operate in the transitional regime, where “turbulence structures” are difficult to capture. Recent work has demonstrated good agreement between experimental 2D-PIV data and CFD simulations for Newtonian fluids using a Stress Blended Eddy Simulation (SBES) closure, obtained for a stirred tank equipped with a A320 hydrofoil impeller, over a wide range of Reynolds numbers in the transitional flow regime. SBES is a hybrid model developed by Ansys employing a RANS k–ω SST model close to the wall boundaries and LES in the bulk. Previous in-silico studies on non-Newtonian fluids in the transitional regime have used RANS or LES approaches but not SBES. In this study the use of SBES (Ansys 2025R2) is extended to non-Newtonian fluids in the transitional flow regime. The simulations were carried out in a tank diameter, T = H = 0.19 m, the impeller diameter, and clearance being D = T/2 and C = T/3, respectively. The fluid used was a shear-thinning 0.6% wt aqueous carboxymethyl cellulose solution that gives a Reynolds number of approximately 1900. Flow fields obtained with SBES and a RANS model (GEKO) were compared with 2D-PIV data, with the SBES model showing the best agreement.
