Fluidization of 1204 spheres: simulation and experiment
نویسندگان
چکیده
In this paper we study the fluidization of 1204 spheres at Reynolds numbers in the thousands using the method of distributed Lagrange multipliers. The results of the simulation are compared with a real experiment. This is the first direct numerical simulation of a real fluidized bed at the finite Reynolds number encountered in the applications. The simulations are processed like real experiments for straight lines in lot-log plots leading to power laws as in celebrated correlations of Richardson and Zaki [1954]. The numerical method allows for the first ever direct calculation of the slip velocity and other averaged values used in two-fluid continuum models. The computation and the experiment show that a single particle may be in balance under weight and drag for an interval of fluidizing velocities; the expectation that the fluidizing velocity is unique is not realized. The numerical method reveals that the dynamic pressure actually decreases slowly with the fluidizing velocity. Tentative interpretations of these new results are discussed.
منابع مشابه
Direct Numerical Simulation of Fluidization of 1204 Spheres
One goal pursued there is to demonstrate that numerical experiments on fluidization can be processed in log-log plots for straight lines leading to power laws as did Richardson and Zaki 1954 for real experiments. As far as we know, we are the only group of researchers to carry out this program. There is no prior literature, in which power laws are obtained from numerical experiments. On the oth...
متن کاملVertically shaken column of spheres. Onset of fluidization
The onset of surface fluidization of granular material in a vertically vibrated container, z = A cos (ωt), is studied experimentally. Recently, for a column of spheres it has been theoretically found [1] that the particles lose contact if a certain condition for the acceleration amplitude z̈ ≡ Aω/g = f(ω) holds. This result is in disagreement with other findings where the criterion z̈ = z̈crit = c...
متن کاملNumerical Simulation of Fluidization and Sedimentation Phenomena
Motivated by the direct numerical simulation of particulate flow (i.e., of the motion of fluid-particle mixtures) the authors of this paper, with the assistance of several collaborators, have introduced some years ago a computational methodology based on a fictitious domain formulation involving distributed Lagrange multipliers defined over the particles; this approach allows the flow computati...
متن کاملMathematical model and numerical simulation of the liquid fluidization of polydisperse solid particle mixtures
A mathematical model for the fluidization of polydisperse suspensions is developed. The stationary concentration configurations for a given fluidizing velocity are analyzed and a mixing condition for bed inversion is derived. A central finite difference scheme is applied to the simulation of the fluidization of a bidisperse suspension. The numerical simulations agree with the experimentally rep...
متن کاملParticle Technology and Fluidization Simulation of Fluidized Beds and Other Fluid- Particle Systems Using Statistical Mechanics
The expansion behavior and structural phenomena of fluid-particle systems was simulated using a method analogous to the Monte Carlo method for molecular systems. Individual particles are moved, and the resulting moves are accepted or declined based on the change in the system’s potential energy and the average kinetic energy of the system. Several fluid particle systems have been successfully p...
متن کامل