The Effect of Numerical Diffusion on Isolated Bubbles in a Gas-Solid Fluidized Bed
نویسنده
چکیده
A two-fluid hydrodynamic model of a two-dimensional gas-solids fluidized bed is used to calculate the shape of an isolated bubble. The calculations are done by applying four different discretization schemes to the convection term. The bubble shape calculated by using the first order upwind scheme is unphysical and pointed, where as the bubble shape calculated by the second order schemes SMART, Superbee, and MINMOD is physically realistic and rounded. Grid independence of the solutions is established. Superbee and SMART are found to give the most accurate results for a given grid resolution. Higher order discretization schemes are implemented with a downwind factor(DWF) method and with a deferred correction(DC) method. The DC method is significantly faster than the DWF method.
منابع مشابه
CFD-DEM Investigation on van der Waals Force in Gas-Solid Bubbling Fluidized Beds
Effect of interparticle force on the hydrodynamics of gas-solid fluidized beds was investigated using the combined method of computational fluid dynamics and discrete element method (CFD-DEM). The cohesive force between particles was considered to follow the van der Waals equation form. The model was validated by experimental results from literature in terms of bed voidage distribution and Eule...
متن کاملEffect of Bed Diameter on the Hydrodynamics of Gas-Solid Fluidized Beds
Effect of scale on the hydrodynamics of gas-solid fluidized beds was investigated in two fluidized beds of 152 mm and 78 mm in diameter. Air at room temperature was used as the fluidizing gas in the bed of sand particles. The Radioactive Particle Tracking (RPT) technique was employed to obtain the instantaneous positions of the particles at every 20 ms of the experiments. These data were u...
متن کاملCFD simulation for segregation behavior of a ternary mixture in a bubbling fluidized bed: effect of solid wall boundary condition
Abstract The effect of the solid–wall boundary condition on the segregation behavior of a sand ternary mixture differing in size but having the same proportion has been investigated in a gas–solid bubbling fluidized bed. A multi-fluid computational fluid dynamics model incorporating the kinetic theory of granular flow has been used. The mass fraction profiles of the different-sized partic...
متن کاملNumerical Simulation of the Hydrodynamics of a Two-Dimensional Gas—Solid Fluidized Bed by New Finite Volume Based Finite Element Method
n this work, computational fluid dynamics of the flow behavior in a cold flow of fluidized bed is studied. An improved finite volume based finite element method has been introduced to solve the two-phase gas/solid flow hydrodynamic equations. This method uses a collocated grid, where all variables are located at the nodal points. The fluid dynamic model for gas/solid two-phase flow is based on ...
متن کاملBubble formation on a single orifice in a gas solid fluidized bed using digital image analysis
Digital Image Analysis (DIA) has been employed to characterize the time evolution of a bubble injected from a single orifice into a pseudo 2-dimansional gas-solid fluidized bed. The injected bubble diameter increased with the square root of time before detachment. During bubble free flight in the bed, its diameter remains approximately constant. The center of mass of the bubble increases with t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1998