Detailed computer simulation

Information about computer simulation methods is given in-Annex 4. 

It is important that the computer code chosen is suitable for carrying out physical property calculations for pure gassy systems. Most simulation codes require the reaction mechanism to be sufficiently well understood that data including stoichiometric coefficients for the reaction and the molecular weight of the evolved gas(es) can be supplied. It is recommended that these data be derived from suitable adiabatic experiments (see Annex 2). A few codes make direct use of adiabatic experimental data, so that a full understanding of the reaction is not required. Most codes assume that the evolved gas can be treated as ideal, and, if this is not the case, an appropriate code must be found. 

Direct scale-up may be used to obtain a relief system size that is less conservative than the DIERS equation. Direct scale-up and its many conditions of applicability are detailed in A5.12. A direct scale-up test is only applicable if the test reactor empties totally by two-phase relief161, and the applicability of the method can therefore only be assessed after the scale-up test has been performed. Direct scale-up may not be feasible if the reacting system contains solids with a particle size similar to or larger than the diameter of the small-scale relief system. 

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Upon completion of both the preliminary and detailed site investigation, a conceptual model can be prepared. A conceptual model is essentially a site model which includes all of the information that has been acquired for the site from both preliminary and detailed investigations, as well as other investigations not directly related to the site. The conceptual model can be anything from simple diagrams to detailed computer simulations, depending ujran the complexity of the site. The model must be continually updated to include new information as it is developed. 

Besides crystalline order and structure, the chain conformation and segment orientation of polymer molecules in the vicinity of the surface are also expected to be modified due to the specific interaction and boundary condition at the surface between polymers and air (Fig. 1 a). According to detailed computer simulations [127, 128], the chain conformation at the free polymer surface is disturbed over a distance corresponding approximately to the radius of gyration of one chain. The chain segments in the outermost layers are expected to be oriented parallel to the surface and chain ends will be enriched at the surface. Experiments on the chain conformation in this region are not available, but might be feasible with evanescent wave techniques described previously. Surface structure on a micrometer scale is observed with IR-ATR techniques [129],... 

Where the Leung methods are inapplicable, a detailed computer simulation can be used to sizing the relief system (see Annex 4). In such cases, care should be taken that the computer code models all necessary features of the relieving runaway reaction. Therefore computer simulations are best carried out by competent specialists. 

As for gassy systems, detailed computer simulation or direct scale-up (if applicable) can be used as alternative relief sizing methods for untempered hybrids. These methods are further discussed in section 7.4. 

Much more sophisticated models are needed to explicitly deal with the role of the solvent and presumably the only sensible way to make headway here is by means of detailed, that is, atomistic computer simulations. Unfortunately, detailed computer simulations of the self-assembly of large polymeric objects are often not very practical because they require excessive computer processing times, in particular if the solvent molecules are... 

Limitations of Potentiometry Need for Detailed Computer Simulations... 

This result can be obtained from simple scaling arguments of the zonal-mean equations (8)-(12) and is consistent with detailed computer simulations. 

In this two-component model, the specific geometries of the deposited clusters have not been considered a potentially important factor in defining the specific shape of the seahorse-like patterns. In fact, the model does not rely on whether the deposited species is a cluster or a single atom. Results of a detailed computer simulation, examining quantitatively and on the atomic scale the effects of a second (charged) component on pattern formation in a DLA-based model, will be published elsewhere. 

Quantitative description of the stretch is a key problem for both laminar and turbulent combustion. Experimental data obtained for the stretch effect on a premixed flame have been proven by theory and by detailed computer simulation [7-14]. It has been found that when the stretch value is small, its effect on the flame velocity is linear. The change in the burning velocity can be expressed by the so called Markstein length [3, 4, 11, 12] found from the equation ... 

The continuous advances in experimental techniques have allowed detailed studies, for instance, in the early stages of crystallization, the results of which carmot be fully explained by the polymer crystallization theory proposed by Lauritzen and Hoffman in the 1960s. Also, the improvements in simulation packages have allowed very detailed computer simulations of the crystallization process, and those results are also not completely described by the LH model. This has generated the proposal of new polymer crystallization theories (i.e., the multistage model proposed by Strobl) and the corresponding debate in the pol)uner crystallization community. 

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