Numerical Model Studies

FIGURE 11-3. Jetties under Study on Idealized Inlet Research Study at WES. Courtesy of US. Army Corps of Engineers. 

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Numerous modeling studies of CVD reactors have been made and are summarized in recent review papers (I, 212). Table 3 in reference 212 lists major examples of CVD models up to mid-1986. Therefore, rather than giving an exhaustive list of previous work, Table V presents a summary of the major modeling approaches and forms the basis for the ensuing discussion, which is most appropriately handled in terms of two groups (1) hot-wall LPCVD systems and (2) cold-wall, near-atmospheric-pressure reactors. In LPCVD reactors, diffusion and surface reaction effects dominate, whereas in cold-wall reactors operated at near-atmospheric pressures, fluid flow and gas-phase reactions are important in predicting performance, as discussed earlier in relation to transport phenomena. 

Rahman, M.H., Wasiuddin, N.M. and Islam, M.R. (2004) Experimental and numerical modeling studies of arsenic removal with wood ash from aqueous streams. Canadian Journal of Chemical Engineering, 82(5), 968-77. 

The properties of nanocomposite systems, whose microstructures aim at reproducing real systems, have been examined in various numerical modelling studies [127, 128], In general, the essential features of the hysteresis cycles may be satisfactory reproduced. In particular, soft layer reversal is quantitatively accounted for, which is expected for reversible phenomena. By contrast, the calculated high-field irreversible reversal of the hard phase magnetization is not reproduced in general. Such discrepancy illustrates the already mentioned difficulty to describe irreversible processes. 

It is to such applications that the numerical model studies are directed. That is, the predictions of the model are... 

For reactions in which ceria is a source of oxygen (as opposed to being a sink for oxygen), the detailed mechanism is thought to involve adsorption of the reductant on the noble metal, extraction of oxygen from the ceria, and reaction between the reductant and oxygen on (or in the periphery oO the metal. This view is consistent with the results of numerous model studies conducted in both UHV, such as CO and H2 TPD/TPR, as well as at normal pressure, such as transient and steady-state CO oxidation, WGS, and steam-reforming reactions (e.g., [8]). 

Further aspects of the halogen reaction cycles that were discussed in Section 4.02.2 were the subject of numerical modeling studies. Using a box model based on Vogt et al. (1996), Dickerson et al. (1999) showed for scenarios for the Indian Ocean that O3 diurnal variations in the MBL could partly be explained by bromine reaction cycles. Another process that was found to be important for diurnal cycles of O3 in the MBL is the establishment of an O3 gradient between the continent and the ocean through advection of continental air with elevated O3 and photochemical... 

In the following, the measurement techniques and the fundamentals of the numerical modelling studies as well as their application on small scale domestic wood stoves will be described. Furthermore, relevant experimental results and information obtained by the numerical modelling studies as well as a detailed comparison of measured and computed data will be shown by means of an example for a commercially available tile stove heating insert. 

Yamada, T. (1982) A numerical model study of turbulent airflow in and above a forest canopy, J. of Meteorological Society of Japan Vol. 60, No. 1,439 154. 

There are three types of numerical model studies, i.e., continental scale ice-sheet/drainage modelling, site-scale permafrost modelling and coupled H-M rock mass modelling. This paper pertains to the last type of nrHxlelling, as conducted by the AECL and CTH teams. Further details on other aspects of BMT3 can be found in Boulton and Hartikainen (2003) and Boulton et al. (2003). 

So far, numerous modeling studies have been carried out to elucidate the electrochemical behavior of PEM fuel cells, and for this purpose, many empirical equations have been introduced to mimic the polarization curves. Srinivasan et al. [160, 161] developed the following equation to describe the relation between the cell voltage, E, and current density, i, in the low and intermediate current density ranges, where the electrochemical reaction is controlled by the activation and ohmic losses ... 

Fuhrmann J, Zhao H, Holzbecher E, Langmach H, Chojak M, Halseid R, Jusys Z, Behm 1 (2008) Experimental and numerical model study of the hmiting current in a channel flow cell with a circular electrode. Phys Chem Chem Phys 10 3784-3795... 

To approximate this experimental observation and the results obtained from the three-dimensional numerical model study, the multiple shock Forest Fire model was used. The Forest Fire rate was determined by the first shock wave or the rates determined by any subsequent release waves that result in lower pressures and lower decomposition rates. As suggested by the three-dimensional study described in Chapter 3, the Arrhenius rate was added using the local partially burned explosive temperatures to the Forest Fire rate. 

Charles Forest, A Numerical Model Study of Burning and Detonation in Small PETN-Loaded Assemblies , Los Alamos National Laboratory report LA-8790 (1981). 

Numerical model studies, in both the near- and far-field. 

Over the past 40 years, numerous modeling studies have focused on the cellular slime mold Dictyostelium discoideum. This is because D. discoideum provides an experimentally accessible and relatively simple system for studying key developmental processes like chemotaxis, cell sorting, and complex pattern formation. Early studies adopted continuous models [77-80]. More recent studies used elegant hybrid approaches that combined CA models and partial differential equations to model 2D and 3D problems involving aggregation and self-organization ofD. discoideum [81-84]. 

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