State of the Art and Future Trends in CFD Simulation of Stirred Vessel Hydrodynamics

Abstract

Computational fluid dynamics (CFD) has become a widely used tool for analysing, optimising and supporting the design of mixing processes in stirred vessels. The present contribution gives a brief summary of the methods applied for numerically treating the power input by the impeller, such as empirical methods, the multiple frame of reference approach and unsteady methods using sliding or clicking meshes. Thereafter, recent developments and trends in the numerical computation of single phase flows in stirred vessels on the basis of DNS (direct numerical simulations), LES (large eddy simulations) and RANS (Reynolds-averaged Navier-Stokes) approaches are summarised. Since many operations in stirred vessels involve at least two phases, also the methods for modelling these flows, such as the two-fluid method and the Euler/Lagrange approach are briefly described and recent applications are reviewed. Finally, also own calculations for single-phase mixing and particle dispersion in a stirred vessel using the Euler/Lagrange approach are introduced emphasising some recent developments.

Models and Applications for Simulating Turbulent Solid–Liquid Suspensions in Stirred Tanks

“…Sommerfeld and Decker (2004) found strong nonphysical accumulation of particles near the bottom wall of the tank if the interparticle collisions were not considered. The importance of particle-particle collisions was emphasized by Derksen (2003).…”

“…In order to simulate turbulent continuous single-phase flows, three approaches are usually utilized: Reynolds averaged NavierStokes (RANS) simulation, large eddy simulation (LES), and direct numerical simulation (DNS). These approaches and their applications to stirred tanks have been reviewed in detail by Sommerfeld and Decker (2004), Van den Akker (2010), and Joshi et al (2011aJoshi et al ( , 2011b. The present section focuses on the models for simulating the influence of the discrete phase on the continuous phase in comparison with single-phase flows.…”

Investigation of Mixing in Shear Thinning Fluids Using Computational Fluid Dynamics

“…In the outer region, the relatively small time derivative terms can be neglected. Upon comparing numerical predictions obtained from applying different impeller modeling methodologies, several investigators observed that steady state methods such as MRF can i. provide reasonable predictions to flow field features and power consumption (Jaworski et al, 2001;Bujalski et al, 2002;Kelly & Gigas, 2003;Khopkar et al, 2004;Aubin et al, 2004;Sommerfeld & Decker, 2004;Khopkar et al, 2006), and ii. save about one-seventh of the CPU-time (Brucato et al, 1998).…”

Study of Error Propagation in Mesh Caused by Surface Point Movement in FVM Systems

“…Among them, the discretization error is generally the largest one. The analysis of discretization error is even more vital in free surface simulations [1,2] such as bubble in the water, vessel with blood etc. Because cell size and cell shape is always changing which would lead to a varied discretization error.…”