Experimentally Validated Computational Fluid Dynamics Simulations of Multicomponent Hydrodynamics and Phase Distribution in Agitated High Solid Fraction Binary Suspensions

The mixing of dense (5–40 wt %) binary mixtures of glass particles in water has been studied in a stirred vessel at the “just-suspended” speed and at speeds above it, using a Eulerian–Eulerian computational fluid dynamics (CFD) model. For each phase component, numerical predictions are compared to 3-dimensional distributions of local velocity components and solid concentration measured by an accurate technique of positron emission particle tracking. For the first time, it has been possible to conduct such a detailed “pointwise” validation of a CFD model within opaque, dense multicomponent slurries of this type. Predictions of flow number and mean velocity profiles of all phase components are generally excellent. The spatial solid distribution is well-predicted except near the base of the vessel and underneath the agitator where it is largely overestimated; however, predictions improve significantly with increasing solid concentration. Other phenomena and parameters such as particle slip velocities and homogeneity of suspension are analyzed

Discrete multi-physics: A mesh-free model of blood flow in flexible biological valve including solid aggregate formation

<div><p>We propose a mesh-free and discrete (particle-based) multi-physics approach for modelling the hydrodynamics in flexible biological valves. In the first part of this study, the method is successfully validated against both traditional modelling techniques and experimental data. In the second part, it is further developed to account for the formation of solid aggregates in the flow and at the membrane surface. Simulations of various types of aggregates highlight the main benefits of discrete multi-physics and indicate the potential of this approach for coupling the hydrodynamics with phenomena such as clotting and calcification in biological valves.</p></div

106學年度－資訊工程學系學士班轉學考2年級－國文

<p>Velocity magnitude (a), velocity vectors (b) and shear stress (c) at 0.2 m s^-1 (left) and 0.9 m s^-1 (right) calculated with CFD.</p

Solid aggregates: (a) ‘calcification’, (b) ‘free clot’ (c) and ‘filiform clot’.

<p>Solid aggregates: (a) ‘calcification’, (b) ‘free clot’ (c) and ‘filiform clot’.</p

Geometric parameters, fluid conditions, and membrane constants used in the simulations and in the experiments.

<p>Geometric parameters, fluid conditions, and membrane constants used in the simulations and in the experiments.</p

Fragmentation of the agglomerate.

<p>Fragmentation of the agglomerate.</p

Velocity vectors illustrating how the presence of the aggregate affects the hydrodynamics: (a) ‘calcification’, (b) ‘free clot’.

<p>Velocity vectors illustrating how the presence of the aggregate affects the hydrodynamics: (a) ‘calcification’, (b) ‘free clot’.</p

Hard membrane: Comparison between simulations and experiments from [24].

<p>Hard membrane: Comparison between simulations and experiments from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174795#pone.0174795.ref024" target="_blank">24</a>].</p

Algorithm for circular and filiform aggregates.

<p>Algorithm for circular and filiform aggregates.</p

Valve geometry and types of particles used in the simulations.

<p>Valve geometry and types of particles used in the simulations.</p