Large Eddy Simulation and Second-Moment Closure Model of Particle Fluctuating Motion in Two-Phase Turbulent Shear Flows
Turbulence statistics of non-settling discrete solid particles suspended in homogeneous turbulent gas shear flows generated by means of large eddy simulation (LES) are investigated for two different mean shear rates (S = 25 and 50 /s) and three different particle diameters (d = 30, 45 and 60 μm). Concurrently, a second-moment closure model of the particle fluctuating motion, based on separate transport equations for the particle kinetic stresses and the fluid-particle velocity correlations, is described and the corresponding predictions are compared with the simulation results. Large eddy simulation and closure model predictions show that the most noticeable effect of inertia is to increase the degree of anisotropy of the particle fluctuating motion with respect to the fluid one. As a matter of fact, the transverse particle turbulent velocity components are directly controlled by the dragging by the fluid turbulence and decrease with increasing particle relaxation time compared to the fluid turbulence integral time scale. In contrast, the streamwise component increases, due to the influence of both the fluid and particle mean velocity gradients, and eventually exceeds the corresponding gas turbulent component.
KeywordsLarge Eddy Simulation Closure Model Velocity Correlation Shear Stress Component Large Eddy Simula Result
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- Bardina, J., Ferziger, J.H., Reynolds, W.C. (1983): “Improved Turbulence Models Based on Large Eddy Simulation of Homogeneous Incompressible Turbulent Flows”, Dept. Mech. Engen. Rep., TF 19, Standford University, CaliforniaGoogle Scholar
- Deutsch, E., Simonin, O. (1991): “Large Eddy Simulation Applied to the Modelling of Particulate Transport Coefficients in Turbulent Two-Phase Flows”, in Proc. 8th Symp. on Turbulent Shear Flows (Univ. of Munich), Vol. 1,pp. 1011–1016Google Scholar
- Deutsch, E. (1992): “Dispersion de Particules dans une Turbulence Homogéne Isotrope Stationnaire Calculée par Simulation Numerique Directe des Grandes Echelles”, in Collection de notes internes de la Direction des Etudes et Recherches (Electricité de France, 92141 Clamart Cedex)Google Scholar
- Gatignol, R. (1983): “The Faxen Formulae for a Rigid Particle in an Unsteady Non-UniformGoogle Scholar
- Stokes Flow”, J. de Méc. Th. et Appl., Vol. l,pp. 143–160Google Scholar
- He, J., Simonin, O. (1993): “Non-Equilibrium Prediction of the Particle-Phase Stress Tensor in Vertical Pneumatic Conveying”, in Proc. 5th International Symposium on Gas-Solid Flows, ASME FED, Vol. 166, pp. 253–263Google Scholar
- Hinze, J.O. (1972): “Turbulent Fluid and Particle Interaction’, Prog. Heat and Mass Transfer, Vol. 8, pp. 433–452Google Scholar
- Khoudly, M. (1988): “Macrosimulation de Turbulence Homogéne en Présence de Cisaillement et de Gradients Thermiques. Application aux Modéles de Fermeture en un Point”, Ph.D. thesis, Ecole Centrale de LyonGoogle Scholar
- Laurence, D., (1985): “Advective Formulation of Large Eddy Simulation for Engineering Flows”, Notes on Numerical Fluid Mechanics, Vol. 15, pp. 147–160Google Scholar
- Simonin, O. (1991): “Second-Moment Prediction of Dispersed Phase Turbulence”, in Proc. 8th Symp. on Turbulent Shear Flows (Univ. of Munich), Vol. 1, pp. 741–746Google Scholar
- Tchen, C.M. (1947): “Mean Value and Correlation Problems Connected with the Motion of Small Particles Suspended in a Turbulent Fluid”, Ph.D. thesis, DelftGoogle Scholar