Fluid Flow and Distributive Mixing Analysis in the Cavity Transfer Mixer

Abstract

In the polymer industry good mixing is essential to guarantee the characteristics of finished products. However, optimizing mixing devices is often difficult because mixing mechanisms are the result of the complex interaction between the moving elements and the non‐Newtonian fluids used. Full 3D simulations are computationally expensive and the complexity of the problem is often split into approximated subproblems. The present work focuses on a simplified 2D model of the Cavity Transfer Mixer, investigating stretching and folding mixing actions. Several geometrical and functioning parameters, such as cavity speed, cavity shape, intercavity distance, rotor–stator clearance, and fluid rheology are varied. Mixing is analyzed in terms of Poincaré maps and by simulating the evolution of fluid blobs. The intercavity distance is found to play a major role, enabling and governing the stretching actions inside the mixing device.

Finite Element Modeling of a Viscous Fluid Flowing through an External Gear Pump

“…[ 33 ] Grosse et al. [ 34 ] quite recently used fluid flow simulations to analyze cavity transfer mixers.…”

“…The inter-teeth volumes are in theory perfectly sealed, simulations enabled the group to introduce methods like the fictitious domain method [32] or the diffuse mapping method. [33] Grosse et al [34] quite recently used fluid flow simulations to analyze cavity transfer mixers.…”

Refractive Index-Matched PIV Experiments and CFD Simulations of Mixing in a Complex Dynamic Geometry

“…10 Recently, Grosso et al captured stretching-and-folding mixing actions inside the device and assessed the impact of geometrical and operational variables by a two-dimensional mixer model. 11 Optical measurement techniques with laser light sources such as Particle Image Velocimetry (PIV) have been used in various areas to investigate single-phase flow, two miscible fluid flow and dilute two-phase flow. [14][15][16][17][18] Refractive index matching (RIM) is a technique commonly used to overcome optical inaccessibility of multiphase systems and complex geometries.…”

“…Their work found that the number of cavities per row and the dimensionless number k defined as the ratio between the axial and the tangential velocity of the fluid at the inlet are the two critical factors for the performance of the dynamic mixer. Many studies simplified dynamic mixers into two-dimensional approximations and conducted corresponding simulations. − Woering et al proposed a more specific and quantitative mixing analysis by investigating the interactions between two rectangular cavities . Recently, Grosso et al captured stretching-and-folding mixing actions inside the device and assessed the impact of geometrical and operational variables by a two-dimensional mixer model …”

Three‐Dimensional Finite Element Modeling of a Viscous Fluid Flowing through an External Gear Pump

“…A suitable method to visualize the high residence time zones in the 3D simulations is to use particle tracking to characterize the process of mixing. [34][35][36][37][38]…”