Fluid Flow Phenomena

All velocity measurements were carried out for a bath depth of //l = 80 x 10 m although the mixing time measurements were done for H = 100 x 10 m. This difference did not cause any problem because the flow patterns for //l = 80x10 m and 100 X 10 m were nearly the same. 

The radial distributions of the axial and radial mean velocity components, u and V, are shown in Figs. 7.3 and 7.4, respectively. The distribution indicates that water moves upward for r 20 x 10 m and downward for 20 x 10 m r 40 X10 m. The broken line in each figure denotes the location of the outer edge of the circular cylinder. Outside this region (r 40 x 10 m), u and v nearly vanish. In other words, a dead water region develops for r 40 x 10 m. 

For the purpose of a better understanding of the flow field in the bath with the CAS model, the resultant velocity vectors for u and v are presented in Fig. 7.5. Only in the inner region of r 40x 10 m, is violent vertical water motion evident. Thus, the CAS model almost completely suppresses the recirculation motion in the radial region outside the outer edge of the circular cylinder. This is mainly responsible for the long mixing time obtained with the CAS model. 

The radial mean velocity v exhibits a relatively high positive value beneath the bath 

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Boyce. M.P., Fluid Flow Phenomena in Dusty Air, (Thesis), University of Oklahoma Graduate College, 1969, p. 18. 

LPCVD reactor modeling involves many of the same issues of multi-component diffusion reactions that have been studied in the past decade in connection with heterogeneous catalysis. Complex fluid-flow phenomena strongly affect the performance of atmospheric-pressure CVD reactors. Two-dimensional and some three-dimensional flow structures in the classical horizontal and vertical CVD reactors have been explored through flow visual-... 

Fluid-flow phenomena The mixing of one fluid in another, immiscible fluid by convection and molecular diffusion during flow through capillary spaces or porous media. 

Preprocessing. Especially for analysis of fluid flow phenomena in complex geometries, the availability of efficient and easy-to-use preprocessors for both problem definition and grid generation is of crucial importance. Fortunately, most commercially available CFD packages meet this requirement. 

Following the recent developments in microfabrication, a number of major research initiatives have been launched to improve our understanding of the heat transfer and fluid flow phenomena at the micro level. A survey of the literature presented below gives a brief summary of the research carried out in single-phase forced convection in microchannels mostly in the last 15-20 years. 

By fluid flow phenomena such as turbulent flow or particulate erosion. (3) Cathodic depolarizers the most common is dissolved oxygen. 

Streamlines and stream tubes. Discussions of fluid-flow phenomena are facilitated by visualizing, in the stream of fluid, fluid paths called streamlines. A streamline is an imaginary curve in a mass of flowing fluid so drawn that at every point on... 

The hydrauhc radius is a useful parameter for generali2dng fluid-flow phenomena in turbulent flow. Equation (5.7) can be so generalized by substituting 4 ... 

Reductions in heat transfer coefficients (up to 25%) were found at low values of average vibrational velocity, v = 2FH. However, in every case as the vibrational velocity was increased heat transfer coefficients increased significantly. Since the goal of this study was to investigate possible improvements in heat transfer using vibration, it was considered appropriate to concentrate on the improvements. Results and analyses, presented previously, neglected data below the threshold values of vibrational intensity required for significant improvement in heat transfer rate. These reductions may be unique to the experimental apparatus utilized however, since others such as Jackson (5) have reported such decreases, this is not felt to be the case. Rather, it seems likely that some not yet identified fluid flow phenomena are involved. 

SPIERS, R.P., SUBBARAMAN, C.V. WILKINSON, W.L. 1974. Free coating of a Newtonian liquid onto a vertical surface. Chem. Eng. Sci. 29, 389-396. SZEKELY, J. 1979. Fluid Flow Phenomena in Metals Processing. New York Academic. TAYLOR, G.I. 1961. Deposition of a viscous fluid on the wall of a tube. J. Fluid Mech. 10, 161-165. 

J. Szekely, Fluid Flow Phenomena in Metals Processing. Academic Press, New York, U.S.A., 1979,178-203. 

It is commonly accepted that the finite element methods offer the most rigorous numerical schemes for the simulation of fluid flow phenomena. The inherent flexibility of these schemes and their ability to cope with complicated geometries and boundary conditions can be used very effectively to solve the governing equations of complex flow regimes. In particular, the finite element simulation of steady, incompressible laminar flow is very well-established, and an extensive literature in this area is available. Galerkin finite element schemes based on different types of Lagrange elements are the most frequently used techniques in these simulations [8]. In flow domains with porous walls, however, more recent work... 

D. Robertson and S. Kang, "Model Studies of Heat Transfer and Flow in Slag-Cleaning Furnaces," Fluid Flow Phenomena in Metals Processing, (1999), 157-168. 

Mass and heat transfer rates are both dependent on the proper description of the fluid flow phenomena in the system. The ideal case is when all of these processes are determined separately and then combined into the system s model in a rigorous manner. However, very often this is quite difficult in experimental measurement therefore, special experiments need to be devised, coupled with the necessary mathematical modeling, in order to decouple the different processes implicit in the measurements. 

The subjects in this chapter will include fluid statics, fluid flow phenomena, categories of fluid flow behavior, the equations of change relating the momentum transport, and the macroscopic approach to fluid flow. 

The heat and mass transfer and fluid flow phenomena in the planar micro-SOFC is described by the CFD model. Due to the low gas velocity and small size of the SOFC, the Reynolds number in the micro-channel is usually much lower than 100 (Yuan et al., 2003). Thus, the gas flow in an SOFC is typically laminar. From a heat transfer analysis, it is found that the local thermal equilibrium assumption is valid for the porous electrodes of an SOFC (Zheng et al., 2013). The governing equations for the CFD model include mass conservation, momentum conservation, energy conservation, and species conservation (Wang, 2004) ... 

In light of the above, we rely on model experiments and theory to provide an improved understanding of fluid flow phenomena in metallurgical processes. In this chapter, the modeling of gas-liquid two-phase flows is classified into two broad categories. Some basic physical situations of relevance in multiphase metallurgical processes are then introduced. Finally, the nature of individual multiphase flows in real processes is discussed. 

Szekely J (1979) Fluid flow phenomena in metals processing. Academic, New York... 

Iguchi M, Nakamura K, Tsujino R (1998) Mixing time and fluid flow phenomena in liquids of varying kinematic viscosities agitated by bottom gas injection. Metall Mater Trans B 29 569-... 

Fundamental studies on heat transfer occurring in ladles have been few in contrast to the considerable body of work that exists on the fluid flow phenomena. It is well known that the real system is non-isothermal because the heat losses through various bounding surfaces of the ladle and the top of the melt result in thermal stratification. 

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