CFD investigation of turbulent dissipation rates in peripheral pumps for micromixing

Abstract

Peripheral pumps are promising micromixing devices due to their intricate internal flow structures and elevated turbulent dissipation rates. This study presents a detailed computational fluid dynamics (CFD) analysis of turbulent dissipation in a peripheral pump, employing transient unsteady Reynolds-averaged Navier–Stokes (URANS) simulations with the k - ω Shear Stress Transport (SST) turbulence model. The analysis reveals that peripheral pumps can achieve exceptionally high turbulent dissipation rates up to 6000 W kg -1 , comparable to specialized high-shear mixers despite operating at moderate Reynolds numbers in the range 3.1 × 10 4 to 5.5 × 10 4 . The highest dissipation rates are localized within the impeller blade passages, driven by characteristic flow exchange between the impeller and sidechannel, in the breaker channel, and in zones of elevated dissipation and distinctive formation patterns downstream in the breaker channel wake. Kolmogorov scale analysis reveals extensive regions with η < 5 µ m and τ η < 1 m s , which indicates sensitivity to the shaft speed, but is largely unaffected by volumetric flow rate. In contrast, mixing efficiency, which is defined as the ratio of the power associated with the turbulent dissipation rate to the hydraulic power input and ranges from 20 % to 55 %, decreases slowly with increasing flow rate and is nearly unaffected by shaft speed. The study establishes that peripheral pumps offer significant potential as micromixing devices, achieving performance levels comparable to dedicated high-shear mixers while providing operational flexibility and unique flow characteristics. These findings support the application of peripheral pumps in processes requiring intense mixing at small scales, particularly in chemical and pharmaceutical industries.