Computational fluid dynamics theory

In theory it should be possible to calculate the capture efficiency without measurements. Some attempts have used computational fluid dynamics (CFD) models, but difficulty modeling air movement and source characteristics have shown that it will be a long time before it will be possible to calculate the capture efficiency in advance. ... 

The thermodynamics of irreversible processes should be set up from the scratch as a continuum theory, treating the state parameters of the theory as field variables [32]. This is also the way in which classical fluid mechanic theory is formulated. Therefore, in the computational fluid dynamics literature, the transport phenomena and the extensions of the classical thermodynamic relations are both interpreted as closures of the fluid dynamic theory. The validity of the thermodynamic relations for fluid dynamic systems has been approached from the viewpoint of the kinetic theory of gases [13]. However, any Arm distinction between irreversible thermodynamics and fluid mechanics... 

Jiang B The Least-Squares Finite Element Method Theory and Applications in Computational Fluid Dynamics and Electromagnetics. Springer, Berlin... 

Measurements have been made of turbulence structure by a number of workers using laser-Doppler methods and using hot-film anemometry Application of computational fluid dynamics to turbulent flow in stirred tanks is developing rapidly and involves using assumptions inherent in Kolmogoroff s theory and turbulence measurements to supply boundary conditions. 

Abstract In an effort to characterize fuel sprays using Computational Fluid Dynamics (CFD) codes, a number of spray breakup models have been developed. The primary atomization of liquid jets and sheets is modeled considering growing wave instabilities on the liquid/gaseous interface or a combination of turbulence perturbations and instability theories. The most popular approaches for the secondary atomization are the Taylor Analogy Breakup (TAB) model, the Enhanced-TAB (E-TAB) model, and the WAVE model. Variations and improvements of these models have also been proposed by other researchers. In this chapter, an overview of the most representative models used nowadays is provided. 

Van Baten and Krishna [41] performed a computational fluid dynamics (CFD) study of gas absorption in Taylor flow and found that in some of the experiments of Bercic and Pintar the contact time in the film was indeed long enough to saturate the liquid film fully. For shorter unit cells (or higher velocities), they formulated a mass transfer model of penetration theory for both the caps and the film... 

If similarity theory is applied correctly, the dimensionless numbers and characteristics that are determined are independent of the scale. This makes it possible, by using appropriate scale-up rules, to specify the operating parameters for industrial-scale systems from the results of tests carried out on models. Computational fluid dynamics (CFD) can be used to visualize the impeller system at its full scale, thus contributing to solving scale-up problems. 

The other form of mathematical model is the more rigorous computational fluid dynamics (CFD) approach that solves the complete three-dimensional conservation equations. These methods have been applied with encouraging results (Britter, 1995 Lee et al. 1995). CFD solves approximations to the fundamental equations, with the approximations being principally contained within the turbulence models—the usual approach is to use the K-e theory. The CFD model is typically used to predict the wind velocity fields, with the results coupled to a more traditional dense gas model to obtain the concentration profiles (Lee et al., 1995). The problem with this approach is that substantial definition of the problem is required in order to start the CFD computation. This includes detailed initial wind speeds, terrain heights, structures, temperatures, etc. in 3-D space. The method requires moderate computer resources. 

Figure 10.1 Schematic representation of length and time scales involved in various types of physical models of polymeric and biological systems. CFD = computational fluid dynamics CG-MD = coarse-grained molecular dynamics DPD = dissipative particle dynamics FEA = finite element analysis SCMFT = self-consistent mean field theory ...

Jiang B-N (1998) The least-squares finite element method theory and applications in computational fluid dynamics and electromagnetics. Springer, Berlin... 

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