We present a systematic derivation of a model based on the central moment lattice Boltzmann equation that rigorously maintains Galilean invariance of forces to simulate inertial frame independent flow fields.In this r...We present a systematic derivation of a model based on the central moment lattice Boltzmann equation that rigorously maintains Galilean invariance of forces to simulate inertial frame independent flow fields.In this regard,the central moments,i.e.moments shifted by the local fluid velocity,of the discrete source terms of the lattice Boltzmann equation are obtained by matching those of the continuous full Boltzmann equation of various orders.This results in an exact hierarchical identity between the centralmoments of the source terms of a given order and the components of the central moments of the distribution functions and sources of lower orders.The corresponding source terms in velocity space are then obtained from an exact inverse transformation due to a suitable choice of orthogonal basis for moments.Furthermore,such a central moment based kinetic model is further extended by incorporating reduced compressibility effects to represent incompressible flow.Moreover,the description and simulation of fluid turbulence for full or any subset of scales or their averaged behavior should remain independent of any inertial frame of reference.Thus,based on the above formulation,a new approach in lattice Boltzmann framework to incorporate turbulence models for simulation of Galilean invariant statistical averaged or filtered turbulent fluid motion is discussed.展开更多
The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and le...The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and length of 1.40 m）, which is divided into two sections wherein both the steps of utilization or loading （e.g., adsorption and catalytic reaction） and regeneration of the solid phase can be carried out simulta- neously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e,. 0.30, 0,42, and 0.61 ram. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network （MLPNN）, was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.展开更多
文摘We present a systematic derivation of a model based on the central moment lattice Boltzmann equation that rigorously maintains Galilean invariance of forces to simulate inertial frame independent flow fields.In this regard,the central moments,i.e.moments shifted by the local fluid velocity,of the discrete source terms of the lattice Boltzmann equation are obtained by matching those of the continuous full Boltzmann equation of various orders.This results in an exact hierarchical identity between the centralmoments of the source terms of a given order and the components of the central moments of the distribution functions and sources of lower orders.The corresponding source terms in velocity space are then obtained from an exact inverse transformation due to a suitable choice of orthogonal basis for moments.Furthermore,such a central moment based kinetic model is further extended by incorporating reduced compressibility effects to represent incompressible flow.Moreover,the description and simulation of fluid turbulence for full or any subset of scales or their averaged behavior should remain independent of any inertial frame of reference.Thus,based on the above formulation,a new approach in lattice Boltzmann framework to incorporate turbulence models for simulation of Galilean invariant statistical averaged or filtered turbulent fluid motion is discussed.
文摘The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and length of 1.40 m）, which is divided into two sections wherein both the steps of utilization or loading （e.g., adsorption and catalytic reaction） and regeneration of the solid phase can be carried out simulta- neously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e,. 0.30, 0,42, and 0.61 ram. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network （MLPNN）, was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.
