A Linear Stability Analysis of a Homogeneous Fluidized Bed

Sobral, Yuri Dumaresq; Cunha, Francisco Ricardo

doi:10.5540/tema.2002.03.02.0197

Cited by 2 publications

(3 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where s = x,t. The properties (2.3) are derived from the continuity of φ and the properties of the filter function presented in (2.2) [10]. Now, a density-weighted average process is more appropriat for compressible models.…”

Section: Flow Governing Equationsmentioning

confidence: 99%

Dynamical Simulation and Statistical Analysis of Velocity Fluctuations of a Turbulent Flow behind a Cube

Oliveira

Miserda

Cunha

2007

Mathematical Problems in Engineering

View full text Add to dashboard Cite

A statistical approach for the treatment of turbulence data generated by computer simulations is presented. A model for compressible flows at large Reynolds numbers and low Mach numbers is used for simulating a backward-facing step airflow. A scaling analysis has justified the commonly used assumption that the internal energy transport due to turbulent velocity fluctuations and the work done by the pressure field are the only relevant mechanisms needed to model subgrid-scale flows. From the numerical simulations, the temporal series of velocities are collected for ten different positions in the flow domain, and are statistically treated. The statistical approach is based on probability averages of the flow quantities evaluated over several realizations of the simulated flow. We look at how long of a time average is necessary to obtain well-converged statistical results. For this end, we evaluate the mean-square difference between the time average and an ensemble average as the measure of convergence. This is an interesting question since the validity of the ergodic hypothesis is implicitly assumed in every turbulent flow simulation and its analysis. The ergodicity deviations from the numerical simulations are compared with theoretical predictions given by scaling arguments. A very good agreement is observed. Results for velocity fluctuations, normalized autocorrelation functions, power spectra, probability density distributions, as well as skewness and flatness coefficients are also presented.

show abstract

Section: Flow Governing Equationsmentioning

confidence: 99%

Dynamical Simulation and Statistical Analysis of Velocity Fluctuations of a Turbulent Flow behind a Cube

Oliveira

Miserda

Cunha

2007

Mathematical Problems in Engineering

View full text Add to dashboard Cite

show abstract

“…Therefore, it is extremely important to identify the mechanism behinds bubble formation in order to be able to better understand and control such flows. Over the years several researchers carried out stability analysis for the study of stability in a fluidized bed ( [1], [2], [11]). In [1], the authors used the local averaged equations for momentum and continuity equations.…”

Section: Introductionmentioning

confidence: 99%

“…Over the years several researchers carried out stability analysis for the study of stability in a fluidized bed ( [1], [2], [11]). In [1], the authors used the local averaged equations for momentum and continuity equations. The averaged equations are perturbed with small disturbances from the homogeneous fluidization state, and linearized with respect to the perturbations.…”

Section: Introductionmentioning

confidence: 99%

CFD-DEM simulations in a gas-solid fluidized bed.

Das¹,

Sobral²,

Cunha³

2017

Proceeding Series of the Brazilian Society of Computational and Applied Mathematics

View full text Add to dashboard Cite

A gas-solid fluidized bed consists of mixture of gas-solid in which the particles were suspended by an imposed upward flow. In the present paper, we have carried out two dimensional numerical simulations of gas-solid fluidized bed. CFD-DEM (Computational fluid dynamics-discrete element modeling) approach is used to model two phase flow composed of solid particles and gas inside the fluidized bed. It uses Eulerian and Lagrangian methods to solve fluid and solid particles respectively. Gidaspow drag model is used to model the interaction between gas and solid particles. Numerical simulations were carried out for various inlet gas velocities (75 cm/s to 82 cm/s) for the fluidized bed. The aim of the present work to search for linear waves. It is interesting to note that, the amplitude of disturbances increase with the height. Further, it is observed that growth rate of the amplitude of disturbances is linear for v g = 75 cm/s and nonlinear for v g = 78 to 82 cm/s.

show abstract

A Linear Stability Analysis of a Homogeneous Fluidized Bed

Cited by 2 publications

References 8 publications

Dynamical Simulation and Statistical Analysis of Velocity Fluctuations of a Turbulent Flow behind a Cube

Dynamical Simulation and Statistical Analysis of Velocity Fluctuations of a Turbulent Flow behind a Cube

CFD-DEM simulations in a gas-solid fluidized bed.

Contact Info

Product

Resources

About