The correct calculation of cell void fraction is pivotal in accurate simulation of two-phase flows using a computational fluid dynamics-discrete element method (CFD-DEM) approach. Two classical approaches for void fraction calculations (i.e., particle centroid method or PCM and analytical approach) were examined, and the accuracy of these methodologies in predicting the particle-fluid flow characteristics of bubbling fluidized beds was investigated. It was found that there is a critical cell size (3.82 particle diameters) beyond which the PCM can achieve the same numerical stability and prediction accuracy as those of the analytical approach. There is also a critical cell size (1/19.3 domain size) below which meso-scale flow structures are resolved. Moreover, a lower limit of cell size (1.63 particle diameters) was identified to satisfy the assumptions of CFD-DEM governing equations. A reference map for selecting the ideal computational cell size and the suitable approach for void fraction calculation was subsequently developed. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2000–2018, 2014

Influence of void fraction calculation on fidelity of CFD-DEM simulation of gas-solid bubbling fluidized beds

Modelling of current loads on aquaculture net cages

CFD-DEM modelling and simulation of pneumatic conveying: A review

Hydrodynamic interactions on net panel and aquaculture fish cages: A review

Development of a porous media model with application to flow through and around a net panel

Analytical and experimental investigation of drag on nets of fish cages

Accurate void fraction calculation for three-dimensional discrete particle model on unstructured mesh

Double-diffusive Marangoni convection in a rectangular cavity: Transition to chaos

Dense particulate flow model on unstructured mesh

An ideal tide-topography interaction model is utilized for studying the influence of density stratification (pycnocline depth d, thickness δ, and the density difference Δρa across the pycnocline) on nonlinear disintegration of the first (mode-1) and second (mode-2) baroclinic mode internal tides into internal solitary waves (ISWs). The solution methods include weakly nonlinear analysis and fully nonlinear simulation. It is found that as d increases, even though the energy flux into mode-1 internal tides is always larger than that into mode-2 ones at generation, mode-2 ISWs emerge and mode-1 ISWs are suppressed. As δ increases, the total energy conversion and the fluxes into both mode-1 and mode-2 tides all increase first and then decrease. During propagation, a thick pycnocline is actually not favorable for the emergence of mode-2 ISWs, and the simulated well-developed mode-2 ISWs for a pycnocline of intermediate thickness are due to the tide generation process. As Δρa increases, the total conversion and the fluxes into both mode-1 and mode-2 tides all increase almost linearly. Even though the flux into mode-1 tides is always larger than that into mode-2 ones at generation, mode-1 tides cannot disintegrate but mode-2 ISWs develop very well. During propagation, Δρa has no influence on the generation of ISWs. The present work systematically investigates the influence of density stratification on formation of ISWs by considering both internal tide generation and propagation processes.

Density stratification influences on generation of different modes internal solitary waves

Jie-Min Zhan

Papers

Analytical and experimental investigation of drag on nets of fish cages

Accurate void fraction calculation for three-dimensional discrete particle model on unstructured mesh

Double-diffusive Marangoni convection in a rectangular cavity: Transition to chaos

Dense particulate flow model on unstructured mesh

Density stratification influences on generation of different modes internal solitary waves