High simulation

Various measured quantities such as pressure, torque Brabender measuring extruder, Haake ESM Average to high, subject to instrument High Simulation of the extmsion process... 

Figure 9.9 Nitrogen fluidization at high simulated gravitational field strength comparison of the results of Rietema and Mutsers (1978) (points) with model predictions (continuous curves).

The investigations show that the microfocus high speed radioscopy system is suitable for monitoring the hard particle transport during laser beam dispersing. It is possible to observe and analyse the processes inside the molten bath with the presented test equipment. As a consequence a basis for correlation with the results of a simulation is available. 

Statistical mechanical theory and computer simulations provide a link between the equation of state and the interatomic potential energy functions. A fluid-solid transition at high density has been inferred from computer simulations of hard spheres. A vapour-liquid phase transition also appears when an attractive component is present hr the interatomic potential (e.g. atoms interacting tlirough a Leimard-Jones potential) provided the temperature lies below T, the critical temperature for this transition. This is illustrated in figure A2.3.2 where the critical point is a point of inflexion of tire critical isothemr in the P - Vplane. 

Lenzer T, Luther K, Troe J, Gilbert R G and Urn K F 1995 Trajectory simulations of collisional energy transfer in highly excited benzene and hexafluorobenzene J. Chem. Phys. 103 626-41... 

It is eonnnon praetiee in elassieal eomputer simulations not to attempt to represent intramoleeular bonds by tenns in the potential energy fiinetion, beeause these bonds have very high vibration frequeneies and should really be treated in a quantum meehanieal way rather than in tire elassieal approximation. Instead, the bonds are treated as being eonstrained to have fixed length, and some straightforward ways have been devised to ineorporate these eonstraints into the dynamies (see later). 

Equilibration of the interface, and the establislnnent of equilibrium between the two phases, may be very slow. Holcomb et al [183] found that the density profile p(z) equilibrated much more quickly than tire profiles of nonnal and transverse pressure, f yy(z) and f jfz), respectively. The surface tension is proportional to the z-integral of Pj z)-Pj z). The bulk liquid in the slab may continue to contribute to this integral, indicatmg lack of equilibrium, for very long times if the initial liquid density is chosen a little too high or too low. A recent example of this kind of study, is the MD simulation of the liquid-vapour surface of water at temperatures between 316 and 573 K by Alejandre et al [184]. 

The parameter /r tunes the stiffness of the potential. It is chosen such that the repulsive part of the Leimard-Jones potential makes a crossing of bonds highly improbable (e.g., k= 30). This off-lattice model has a rather realistic equation of state and reproduces many experimental features of polymer solutions. Due to the attractive interactions the model exhibits a liquid-vapour coexistence, and an isolated chain undergoes a transition from a self-avoiding walk at high temperatures to a collapsed globule at low temperatures. Since all interactions are continuous, the model is tractable by Monte Carlo simulations as well as by molecular dynamics. Generalizations of the Leimard-Jones potential to anisotropic pair interactions are available e.g., the Gay-Beme potential [29]. This latter potential has been employed to study non-spherical particles that possibly fomi liquid crystalline phases. 

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