Experimental and Numerical Techniques

The knowledge of turbulent premixed flames has improved from this very simple level by following the progress made in experimental and numerical techniques as well as theoretical methods. Much employed in early research, the laboratory Bunsen burners are characterized by relatively low turbulence levels with flow properties that are not constant everywhere in the flame. To alleviate these restrictions, Karpov et al. [5] pioneered as early as in 1959 the studies of turbulent premixed flames initiated by a spark in a more intense turbulence, produced in a fan-stirred quasi-spherical vessel. Other experiments carried out among others by Talantov and his coworkers allowed to determine the so-called turbulent flame speed in a channel of square cross-section with significant levels of turbulence [6]. 

The aim of this paper is to describe the experimental and numerical techniques that, when combined, provide a procedure that enables full particle-size distribution studies of sub-micrometer emulsion systems. We then present distribution results for several oil/water emulsions to demonstrate the ability of these techniques to monitor the effect of processing variables (such as surfactant concentration) on the final emulsion. Finally, we discuss some of the problems of converting the intensity weighted distribution to a mass weighted distribution and suggest methods for minimizing or eliminating some of these problems. 

T. A., Tellez, G., and Gramann, PJ. [50] used analytical, experimental and numerical techniques to show that rotating the barrel is a correct method to analyze the fluid flow in extrusion. 

The necking mechanism has also been investigated using theoretical and numerical techniques. The theoretical approach, based on small deformation analysis (Barthes-Biesel and Acrivos, 1973) for the case of low Ca or high p shows the formation of lobes on the drop for Ca > Cacrit - Numerical techniques (Rallison, 1981) for p = 1 give similar results. The general conclusion is confirmation of the experimentally determined curve for Cacrit the drops in this case may break up rather than extend indefinitely. 

Waldvogel and Poulikakos1501 extended the model and numerical techniques of Zhao et al.13681 by incorporating solidification and droplet-substrate contact resistance in the heat transfer model. They conducted both theoretical and experimental studies on the impact and solidification of molten solder droplets on a multilayer substrate. The theoretical model was based on the Lagrangian formulation, and accounted for a host of thermal-fluid phenomena,... 

Future directions can be divided into experimental and numerical. The two most obvious experimental directions are (i) extensions to CD spectroscopies so that comparable system identification of stereo-selective systems can be realized and (ii) extension to NMR since it is the most widespread analytical technique in the chemical sciences. Efforts in both directions are currently underway in our laboratory. 

What is next Several examples were given of modem experimental electrochemical techniques used to characterize electrode-electrolyte interactions. However, we did not mention theoretical methods used for the same purpose. Computer simulations of the dynamic processes occurring in the double layer are found abundantly in the literature of electrochemistry. Examples of topics explored in this area are investigation of lateral adsorbate-adsorbate interactions by the formulation of lattice-gas models and their solution by analytical and numerical techniques (Monte Carlo simulations) [Fig. 6.107(a)] determination of potential-energy curves for metal-ion and lateral-lateral interaction by quantum-chemical studies [Fig. 6.107(b)] and calculation of the electrostatic field and potential drop across an electric double layer by molecular dynamic simulations [Fig. 6.107(c)]. 

The interplay between theory and experiment is of importance in high-temperature chemistry. The electronic structures of high-temperature molecules are being studied in detail with numerous experimental and theoretical techniques. Molecular... 

The developed optimisation procedure, consisting of detailed experimental and numerical investigations on the gas concentration, temperature and flow fields, will be also suitable for different small and medium scale wood firing systems with various combustion techniques. 

Experimental methods likely to have important consequences for the preparation and study of fully ordered macromolecules include high pressure skills (15, 66) and numerous techniques using synchrotron radiation. X-ray topography using a synchrotron source has already been used to study the role of defects in PTS polymerization (67). 

Section 1 is aimed at providing new fundamental and practical data for the development of efficient combustion control strategies. It includes development of novel diagnostic techniques to provide in situ meeisurement capabilities, novel computational tools to acquire deeper insight into the fundamental mechanisms, and interactions in two-phase flows and flames relevant to realistic combustors as well as their operating conditions. Further, detailed experimental and numerical studies of the physical and chemical phenomena in turbulent flames, and the novel passive and active control methodologies to control combustion instabili-... 

The last term in Eq. (A-3) is the Laplace transform of E(a) Aweq(a), where a plays the role of t in Eq. (A-4) and t plays the role of s in Eq. (A-4). Thus the problem is reduced to this experimental observations give us the Laplace transform of the desired distribution function [modified by multiplication by Aweq(A)], We want the distribution function. The required calculation is a numerical inverse Laplace transform. This is clearly feasible, and numerical techniques are discussed in the literature 56). It is not a simple matter to carry out, however, and the accuracy requirements on the data are likely to be stringent. No direct method of computing the distribution from frequency response is known, although the step response can be computed from the frequency response by standard techniques. In view of the foregoing discussion, it appears that in principle, at least, the distribution can be computed from the frequency response. 

The origin of attractive intermolecular interactions and the factors determining the geometry of molecular complexes is still being sought after decades of numerous experimental and theoretical techniques. The interaction energy, AE, is the difference between the energy of the species AB and the two isolated molecules A and... 

Structural complexity—The multiscale material structure of a catalytic coating can be accounted for in more detailed terms using sophisticated experimental and modeling techniques (e.g., the work of Koci et al. [8] involving digital reconstruction and numerical solutions at micro- and nanolevels). 

Drops of liquids have held researchers interest for many years. As mathematical curiosities for famous early fluid dynamicists, the pendant drop from a capillary provided an interesting and practical challenge. Young (1805) and Laplace (1806) independently developed the theory of surface tension and drop formation while the first analytical solutions to their theory were completed by Gauss in 1830. Much of the early woik on pendant drops involved numerous methods involving the determination of drop volume or shape with experimental techniques and using the available theory to determine surface tension of the liquid-gas interface. These methods are well detailed in the works by Adamson, Padday, and Reed Hah. ITie studies of the early researches developed into the rich and diversified field of interfacial fluid dynamics. The advancement of theory and numerical techniques has steadily increased the ability of researchers to better understand and control interfacial behaviors. 

Riccardo Nobile is Assistant Professor of Machine Design and Experimental Mechanics at the University of Salento in Italy. Main research interests are fatigue of base and welded materials, experimental techniques for the evaluation and monitoring of fatigue damage process, experimental and numerical evaluation of residual stress, and mechanical characterization of innovative materials and structures. 

In another work the MAS NMR technique is compared to the static powder quadrupole echo (QE) and Jeener-Brockaert (JB) pulse sequences for a quantitative investigation of molecular dynamics in solids. The line width of individual spinning sidebands of the ID MAS spectra were found to be characteristic of the correlation time from 10 to s so that the dynamic range is increased by approximately three orders of magnitude when compared to the QE experiment. As a consequence, MAS NMR is found to be more sensitive to the presence of an inhomogeneous distribution of correlation times than the QE and JB experiments which rely upon line shape distortions due to anisotropic T2 and Tiq relaxation, respectively. All these results have been demonstrated experimentally and numerically using the two-site flip motion of dimethyl sulfone and of the nitrobenzene guest in the a-p-tert-butylcalix[4]arene-nitrobenzene inclusion compound. 

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