Two-fluid model for particle-turbulence interaction in a backward-facing step

Investigations of Gas–Particle Two-Phase Flow in Swirling Combustor by the Particle Stokes Numbers

Gas turbulence modulations and particle dispersions of swirling gas–particle two-phase flow in the combustor is investigated under the large spans of the particle Stokes numbers. To fully consider the preferential concentrations and anisotropic dispersions of a particle, a kinetic frictional stress model coupled with a second-order moment two-phase turbulent model and granular temperature equation is improved. The proposed modeling and simulations are in good agreement with the experimental validations. Results show turbulent modulations and particle dispersions exhibit strongly anisotropic characteristics, keeping a close relationship with flow structure. The axial gas velocity and RMS fluctuation velocity of 45.0-μm EGP was approximately 5.0 times and 3.0 times greater than 1000.0 μm Copper particles, and their axial particle velocity was 0.25 times and twice greater than those of 45.0 μm EGP. The degree of modulation in the axial–radial direction is larger than those of radial–tangential and axial–tangential direction. Particle dispersions are sensitive to particle diameter parameters and intensified by higher Stokes number.

Numerical investigation of indoor particulate contaminant transport using the Eulerian-Eulerian and Eulerian-Lagrangian two-phase flow models

Transport of micron particles in a displacement ventilated room was simulated using both the Eulerian-Eulerian model and the Eulerian-Lagrangian model. The same inter-phase action mechanisms were included in both models. The models were compared against each other in the aspects of air velocity, particle concentration, and particle-wall interactions. It was found that the two models have similar accuracy in predicting the airflow field while each of them has its own advantage and drawback in modelling particle concentration and particle-wall interactions. The E-E model is capable of providing a mechanistic description of the inter-phase interactions, whilst the E-L model has obvious advantage in modelling particle-wall interactions. Advices were given for choosing an appropriate model for modelling particulate contaminant transport in indoor environments.

Study of turbulent energy dissipation rate of fluid flow in the vicinity of dispersed phase boundary using spatiotemporal tree model

The hierarchical shell models of turbulence including a spatial dimension, namely, spatiotemporal tree models, reproduce the intermittent behavior of Navier-Stokes equations in both space and time dimensions corresponding to high Reynolds number turbulent flows. This model is used, for the first time in this paper, in a one-dimensional flow zone containing a dispersed-phase particle that can be used in the study of dispersed-phase flows. In this paper, a straightforward method has been used to introduce discrete phase into the spatiotemporal tree model that leads to an increased amount of turbulent energy dissipation rate in the vicinity of the discrete phase. The effects of particle insertion and particle size on the turbulent energy dissipation rate are demonstrated. Moreover, the space-scale behavior of the time-averaged turbulent energy dissipation rate in the presence of dispersed phase is demonstrated by means of continuous wavelet transform.