The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision ter...The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision term for particles under dense two-phase flow conditions is also derived. In comparison with the governing equations of a dilute two-phase flow,the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations.Based on Cauchy-Helmholtz theorem and Smagorinsky model, a second-order dynamic sub-grid-scale(SGS)model,in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor,is proposed to model the two-phase governing equations by applying dimension analyses.Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls,the velocity and pressure fields,and the volumetric concentration are calculated.The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.展开更多
According to modeling principle that a model must be more accurate ifincluding more flow information, and based on the Cauchy-Helmholtz theorem and the Smagorinskymodel, a second-order dynamic model with double dynami...According to modeling principle that a model must be more accurate ifincluding more flow information, and based on the Cauchy-Helmholtz theorem and the Smagorinskymodel, a second-order dynamic model with double dynamic coefficients was proposed by applyingdimension analyses. The Subgrid-Scale (SGS) stress is a function of both strain-rate tensor androtation-rate tensor. The SIMPLEC algorithm and staggering grid system was applied to give thesolution of the discretized governing equations, and for the turbulent flow through a 90° bend, thedistributions of velocity and pressure were achieved. The comparison between experimental data andsimulation results at a Reynolds- number 40000 shows a good agreement and implies that this model ispracticable and credible.展开更多
基金The project supported by the National Natural Science Foundation of China (50176022)
文摘The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules.Assuming that the solid-phase velocity distributions obey the Maxwell equations,the collision term for particles under dense two-phase flow conditions is also derived. In comparison with the governing equations of a dilute two-phase flow,the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations.Based on Cauchy-Helmholtz theorem and Smagorinsky model, a second-order dynamic sub-grid-scale(SGS)model,in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor,is proposed to model the two-phase governing equations by applying dimension analyses.Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls,the velocity and pressure fields,and the volumetric concentration are calculated.The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.
文摘According to modeling principle that a model must be more accurate ifincluding more flow information, and based on the Cauchy-Helmholtz theorem and the Smagorinskymodel, a second-order dynamic model with double dynamic coefficients was proposed by applyingdimension analyses. The Subgrid-Scale (SGS) stress is a function of both strain-rate tensor androtation-rate tensor. The SIMPLEC algorithm and staggering grid system was applied to give thesolution of the discretized governing equations, and for the turbulent flow through a 90° bend, thedistributions of velocity and pressure were achieved. The comparison between experimental data andsimulation results at a Reynolds- number 40000 shows a good agreement and implies that this model ispracticable and credible.
