Computational fluid mixing

ELIZABETH MARDEN MARSHALL and ANDRE BAKKER Fluent, Inc. 

In Section 5-2, an introdnction to the field of computational fluid dynanfics is given, with an emphasis on the fundamental equations that are used to describe processes that are conunon in nfixing applications. An overview of the numerical methods used to solve these equations is presented in Section 5-3. Numerical simulations of stirred tanks are normally done in either two or three dimensions. In two dimensional (2D) simnlations, the geometry and flow field are assumed to 

Handbook of Industrial Mixing Science and Practice. Edited by Edward L. Paul, 

Fignre 5-lfl shows the outline of a simple baffled stirred tank containing a Rushton turbine on a centrally mounted shaft. The tank has diameter T. The impeller has diameter D and is located a distance C off the bottom of the tank. These symbols are used throughout the chapter. 

Computational fluid dynamics (CFD) is the numerical simulation of fluid motion. While the motion of fluids in mixing is an obvious application of CFD, there are hundreds of others, ranging from blood flow through arteries, to supersonic flow over an airfoil, to the extrusion of rubber in the manufacture of automotive parts. Numerous models and solution techniques have been developed over the years to help describe a wide variety of fluid motion. In this section, the fundamental equations for fluid flow are presented. 

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Computation fluid mixing and computational fluid dynamic techniques have increasingly been used to elucidate solids distribution in agitated vessels [44],... 

Application of Computational Fluid Dynamics and Computational Fluid Mixing in Reactors... 

Blend time and ehemieal produet distribution in turbulent agitated vessels ean be predieted with the aid of Computational Fluid Mixing... 

The objeetive of the following model is to investigate the extent to whieh Computational Fluid Mixing (CFM) models ean be used as a tool in the design of industrial reaetors. The eommereially available program. Fluent , is used to ealeulate the flow pattern and the transport and reaetion of ehemieal speeies in stirred tanks. The blend time predietions are eompared with a literature eonelation for blend time. The produet distribution for a pair of eompeting ehemieal reaetions is eompared with experimental data from the literature. 

Additionally, solutions to problems are presented in the text and the accompanying CD contains computer programs (Microsoft Excel spreadsheet and software) for solving modeling problems using numerical methods. The CD also contains colored snapshots on computational fluid mixing in a reactor. Additionally, the CD contains the appendices and conversion table software. 

Marshall EM, Bakker A. Computational fluid mixing. In Paul EL, Atiemo-Obeng VA, Kresta SM, eds. Handbook of Industrial Mixing Science and Practice. Hoboken, NJ Wiley, 2004 257-343. 

Computational fluid mixing Computer programs that use velocity data to calculate various types of flow patterns and various types of fluid mechanics variables used in analyzing a mixing vessel. 

Many times a specification calls for a fluid mixer to produce a good dispersion of so many computational fluid mixing (CFM), of gas into a given volume of liquid. Actually, there are very few applications in which dispersion of gas-liquid is the ultimate process requirement. Usually there is a mass transfer requirement involved, and the role of a mixer to provide a certain mass transfer... 

ASME CFSTR CFD CFM DIERS exp IR HA/AN HAZOP MM MMM American Society of Mechanical Engineers Continuous flow stirred tank reactor Computational fluid dynamics Computational fluid mixing Design Institute for Emergency Relief Systems exponential Infrared (spectroscopy) Hazard analysis Hazard and operability studies Michaelis-Menten Maximum-mixedness model... 

Computational fluid mixing allows the modeling of flow patterns in mixing vessels and some of the principles on which this is based in current techniques are included. 

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