Free surface phenomena

Lineup of three diti nsional thermal hydraulics simulation is a finite difference method code AQUA SPLASH based on Arbitrary-Eulerian-Lagrangian finite element method and direct simulation code DINUS-3. The AQUA code is being applied to natural circulation and thermal stratification analysis. The SPLASH mostly simulates the free surface phenomena. The DINUS-3 code simulates thermal striping phenomena. Validations of these codes are almost completed and practical problems are currently solved. 

Beebe is partieularly known for hydraulics by his 1917 Report written jointly with Ross Riegel (1881-1966). This woik, made for the Miami Conservancy District, deals with hydraulic jiunps both in prismatic and in expanding stilling basins. Until then, few experimental works were conducted on this important free surface phenomenon. The main works further were conducted for either small supercritical approach flow Froude numbers, or for extremely small approach flow depths, resulting in scale effects. The results were not readily available but demonstrated that these complex hydraulic processes were amenable by hydraulic modeling. Beebe was also involved in the 1930s in the control of debris flow at Mount Shasta In 1924, a large mud flow had deposited almost one million m of debris which muddied the Sacramento River. Beebe outlined means to coimter future similar scenarios, which had also occurred in the 19 century, and were a constant threat to the Sacramento Valley. 

Polyisobutylene and similar copolymers appear to "pack" well (density of 0.917 g/cm ) (86) and have fractional free volumes of 0.026 (vs 0.071 for polydimethylsiloxane). The efficient packing in PIB is attributed to the unoccupied volume in the system being largely at the intermolecular interfaces, and thus a polymer chain surface phenomenon. The thicker cross section of PIB chains results in less surface area per carbon atom. 

So far the structure of pure metals has been discussed with reference to bulk characteristics and continuous crystals. However, corrosion is essentially a surface phenomenon and it is necessary to consider how the structure and defects already described interact with free surfaces. At this stage it is convenient to consider only a film-free metal surface, although of course in most corrosion phenomena the presence of surface films is of the utmost importance. Furthermore, it is at free surfaces that the hard sphere model of metals... 

The close observation of bubbles collapsing at the free surface of a glass poured with champagne also revealed another unexpected and lovely phenomenon. A few seconds after pouring, and after the collapse of the... 

Recently, it has been demonstrated [53] that at room temperature the Ge(0 01) surface does not show a uniform simple reconstruction, but instead an ordered striped pattern consisting of p(2 x 1) and c(4 x 2) domains (see Fig. 4). This striped pattern corresponds to a minimum free energy and can be fully explained in terms of a well-established strain relaxation theory [54]. With increasing temperature the p(2 x 1) domains grow at the expense of the c(4 x 2) domains. It requires extremely clean and defect-free surfaces to observe this phenomenon, which is probably the reason why it hasn t been observed before. In contrast to Ge(00 1) it is inherently difficult to prepare clean Si(00 1) surfaces with defect densities low enough for this pattern to develop. 

The flow computations in a short die (here T= 145 °C) obviously imply free surface determination corresponding to the swell phenomenon. It may be seen in Fig. 37 that the general birefringence patterns are similar, even if the results of the mPTT model seem more realistic in the downstream region than those of the GOB model, for which discontinuities appear along the centreline, apparently due to an incorrect determination of the relaxation time at very low shear rate. 

Interfacial polarization is an autonomous phenomenon in the sense that it always occurs, irrespective of the presence of ionic charges. One of the consequences is that at the point of zero charge generally x so that p.z.c. p.z.p. (point of zero potential). Another manifestation is the existence of a nonzero " at the free surface of water. 

It should also be noted that the crystallization behavior of melt-spun ribbons may be different on both ribbon sides [4.18]. Nucleation for primary crystallization of the transition metals is observed on both sides of the glassy ribbons, while other crystallization reactions have been observed to prefer usually either the free surface or the contact side of the ribbon [4.77]. This phenomenon may lead to different structural and chemical properties of the two ribbon sides, and consequently also to large anisotropy in the catalysts prepared from such ribbons [4.18, 19]. 

Transition radiation is considerably weaker than Cerenkov radiation, however since it is a surface phenomenon it avoids problems with radiator thickness and reflections inherent to Cerenkov-generating silica plates. Optical TR can be measured using a streak camera. An optical TR system has been used to time-resolve the energy spread of an electron macropulse in a free-electron laser facility [10]. Interferometry of coherent, far-infrared TR has been used to measure picosecond electron pulse widths and detect satellite pulses at the UCLA Satumus photoinjector, using charges on the order of 100 pC [11],... 

An application of radiation induced-inactivation, is the determination of the size of the enzyme (216, 217). Nevertheless, care should be taken when using this method as secondary damage due to free radicals generated in the local environment of an enzyme, can influence the apparent target size determined (218). Also, it might be that radiation damage is a surface phenomenon thus not dependent on the volume of the protein but on its surface (19). 

The mechanical and electrical displacements for metalized and free surfaces at liquid-36 YX LiTa03 interface are shown in Figure 4.4a and 4.4b [22]. Most of the acoustic energy is conhned to within one wavelength from the surface of the substrate. When the surface is metalized and electrically shorted, the potential on the surface is zero. In this case, only the normalized displacement (U2) interacts with the liquid loading, and the phenomenon is called mechanical perturbation. If the surface is free and electrically open, then both U2 and normalized electric potential (d>) interact with the adjacent liquid medium (Figure 4.4b). Interactions of d> and the electrical properties of the liquid constitute the acoustoelectric interaction. The influence of both the mechanical and acoustoelectrical interactions on sensor response and material characterization is discussed in the subsequent sections. 

The first spray phenomenon that needs to be modeled is the atomization process, that is, the disintegration of the bulk liquid into tiny droplets. The atomization process can be separated into inner-nozzle and outer-nozzle effects. The forces that govern the inner-nozzle atomization include cavitation-induced and turbulence-induced disturbances of the liquid. Once the liquid exits the nozzle, it interacts with the gaseous environment that induces disturbances on the liquid-gas interface caused by aerodynamic and inertial forces. Also, when the liquid exits the nozzle, it experiences a discontinuity in the boundary condition, namely, from the fixed boundary of the nozzle orifice to a free surface boundary. This abrupt change in the boundary condition leads to disturbances of the liquid that influence the atomization process. In general, the atomization of a bulk liquid is a very complex process and is still the subject of intensive research. 

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