CFD simulation of flow and mixing in‐inline rotor‐stator mixers with complex fluids

Abstract

The objective is to apply CFD methodology for the validation of the scale‐up of rotor‐stator units formed by flat blades and used as in‐line mixers under laminar flow conditions. The comparison between simulated and experimental data as a function of rotor geometry, rotation speed and flow rate has shown a good agreement in terms of power input and RTD curves both for Newtonian and power‐law fluids with a flow index between 0.2 and 1. The applicability of the virtual Couette analogy has been validated quantitatively and explained by the analysis of the local flow in the mixer. As a result, a shear coefficient independent of fluid rheology has been deduced from CFD data. This has been shown to depend only on the dimensionless gap when the length‐to‐diameter ratio is higher than 2.5. In this case, fast 2D simulations can provide a good approximation of the shear coefficient obtained from 3D calculations from which a master power curve can be deduced, but these are not able to predict flow transition, contrary to 3D computations. Finally, original correlations able to estimate the power and shear coefficients as a function of the mixer geometry have been established.

Fluid dynamics study of the flow and pressure drop analysis of a non‐Newtonian fluid through annular ducts with unusual cross‐sections

“…In order to predict all aspects of the flow field, including the distribution of velocities and pressure drops along the well, it is necessary to obtain the solution for the three‐dimensional and transient mass and motion conservation differential equations. For this, CFD can be used through commercial numerical packages . Applying CFD has the advantage of providing detailed information of the flow field and other desired properties without any limitations on experimental conditions, and its application can be useful for designing or analyzing an existing situation …”

“…For this, CFD can be used through commercial numerical packages. [21][22][23][24][25] Applying CFD has the advantage of providing detailed information of the flow field and other desired properties without any limitations on experimental conditions, and its application can be useful for designing or analyzing an existing situation. [26][27][28] Thus, to contribute to the understanding of well cleaning operations and cost reductions, this paper presents experimental and simulated pressure drops, flow fields simulated via CFD of non-Newtonian fluid in concentric and eccentric annular ducts, with and without partial obstruction of the annular region, for cases with and without inner tube rotation.…”

Data-driven surrogate modeling and benchmarking for process equipment

“…The difference in the power number obtained with a finer mesh, with double the resolution, was 0.3%. Table 2 shows the comparison of the power coefficient k p (¼ N p,2D ReL e =d) calculated here and the results obtained by Vial et al (2015) through experiments and two-dimensional simulations. The agreement is very good.…”

“…The third case is representative of flow of Newtonian and power-law fluids in an inline mixer reported by Vial et al (2015). This setup utilizes a two-dimensional geometry, neglecting the effect of the flow in the axial direction.…”

“…The simulations performed were two-dimensional. Vial et al (2015) reported that this simplification was adequate to describe the behavior of the system as long as the flow was in the laminar regime and the nondimensional gap between rotor and stator was kept below 0:2. Thus, these restrictions were considered in the choice of parameter ranges.…”