Entrainment simulation

A large one-sixth-scale model of the unloader hopper was selected so that flow patterns in the enclosure could be evaluated.Smoke was used to simulate the behavior of the lime dust in the enclosure. The lime drop from the clamshell was simulated by releasing coarse sand, thus modeling the flow patterns caused by the volume displacement and the air entrainment. The effects of local wind speed and direction on the enclosure were also simulated. 

Figure 3.51. Computer simulation output for a five stage mixer settler cascade with entrainment.

As shown in Fig. 4.1, resin feedstocks have a considerable level of interparticle space that is occupied by air. This level of space and thus the bulk density of the feedstock depend on the temperature, pressure, pellet (or powder) shape, resin type, and the level and shape of the recycle material. For a specific resin feedstock, the bulk density Increases with both temperature and the applied pressure. Understanding the compaction behavior of a resin feedstock is essential for both screw design and numerical simulation of the solids-conveying and melting processes. Screw channels must be able to accommodate the change in the bulk density to mitigate the entrainment of air and the decomposition of resin at the root of the screw. Typically, screw channels are set by using an acceptable compression ratio and compression rate for the resin. These parameters will be discussed in Section 6.1. 

Chapter 11). The simulations show enhanced vorticity in all three directions with a rich fine structure at later times in the evolution of the jet and an entrainment velocity field qualitatively different from that of around unheated turbulent jets. 

The fuel-to-air ratio was varied from 0.8 to 1.4 to simulate differing soot formation conditions. The fuels used were propane, ethylene, or ethylene with gaseous benzene (the fuel was bubbled through liquid room-temperature benzene to provide up to 20% of the combustible content or the entrainment air flow was bubbled through benzene to provide up to 66%). The centerline velocity at the nozzle exit was 3 m/s, the unforced (natural) RMS was 4.5%, and the forced RMS was 30%. The Reynolds number based on the exit diameter was 3700. 

A major question concerning the development of jet flow subjected to heating is the effect on entrainment. Now because of the periodic boundary conditions imposed on the computational domain in the present simulation, the net entrainment over the domain has to vanish. Nevertheless, as shown below, considerable insight into the problem can be obtained by examining the entraining velocity field, which displays velocity vectors in the ambient fluid in the immediate neighbourhood surrounding the jet. 

Figure 13.1 Near-field entrainment measurements in noncircular jets based on experimental and computational studies [16]. Subsonic regimes. Experiments 1 — elliptic [37] 2 — square [16] 3 — round [38]. Simulations 4 — square [16]. A ...

The goal of this work has been to characterize the effects of the unsteady vor-ticity dynamics on jet entrainment and nonpremixed combustion. The main focus of the numerical simulations of rectangular jets has been on the vortic-ity dynamics underlying axis switching when the initial conditions at the jet exit involve laminar conditions, negligible streamwise vorticity, and negligible azimuthal nonuniformities of the momentum thickness. 

Other fluid dynamic models of slurry flow have also been developed by other workers [57]. Coppeta, Rodgers, Radzak, and coworkers examined slurry flow, both from a simulation point of view, and from an experimental angle [6,10,11]. A special test apparatus is used consisting of flourescent injections of die that is entrained beneath a glass wafer enabling observation of slurry flow patterns and residence time. Such studies are instrumental... 

In a series of experiments we have tested the type and range of entrainment of glycolytic oscillations by a periodic source of substrate realizing domains of entrainment by the fundamental frequency, one-half harmonic and one-third harmonic of a sinusoidal source of substrate. Furthermore, random variation of the substrate input was found to yield sustained oscillations of stable period. The demonstration of the subharmonic entrainment adds to the proof of the nonlinear nature of the glycolytic oscillator, since this behavior is not observed in linear systems. A comparison between the experimental results and computer simulations furthermore showed that the oscillatory dynamics of the glycolytic system can be described by the phosphofructokinase model. 

The ash simulation model (Konstandopoulos et al., 2003 Rodriguez-Perez et al., 2004) consists of ash transport and ash layer evolution equations describing the interaction between ash deposition and re-entrainment in the channels along with the gas mass balance and momentum balance equations in the inlet and outlet channels of the DPF. Ash re-entrainment is initiated by flow... 

To confirm the above conjectures we have performed a numerical simulation of equation (29) on the Brusselator model chemical reaction.46 The results are shown in Fig. 7. We start with an initial condition corresponding to a clockwise wave. Under the effect of the counterclockwise field this wave is deformed and eventually its sense of rotation is reversed. In other words, the system shows a clear-cut preference for one chirality. As a matter of fact we are witnessing an entrainment phenomenon of a new kind, whereby not only the frequency but also the sense of rotation of the system are adjusted to those of the external field. More complex situations, including chaotic behavior, are likely to arise when the resonance condition w = fl, is not satisfied, but we do not address ourselves to this problem here. 

We study the separation of 77-hexane-ethyl acetate mixture by using acetonitrile as a heavy heterogeneous entrainer. The simulation of the process is performed with the batch process simulator ProSimBatch [10]. It enables to evaluate operational parameters like the entrainer amount that are not provided by the feasibility and synthesis analysis The column model consists of usual plate by plate Material balance, Equilibrium, Summation of fractions and Heat balance... 

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