Dynamic roughness

Hsu, S. A. (1974). A dynamic roughness equation and its application to wind stress determination at air-sea interface. J. Phys. Oceanogr. 4, 116-120. 

Table 5.2 Dynamic roughness lengths, zo, for typical atmospheric surfaces (Turner, 1979)...

The value of has not been attempted in the field to date. So, how do we determine Kl for field applications The determination of dynamic roughness, zo, has also been difficult for water surfaces. The primary method to measure Kl and Kq is to disturb the equilibrium of a chemical and measure the concentration as it returns toward either equilibrium or a steady state. Variations on this theme will be the topic of this chapter. 

The exploration of ultrafast molecular and cluster dynamics addressed herein unveiled novel facets of the analysis and control of ultrafast processes in clusters, which prevail on the femtosecond time scale of nuclear motion. Have we reached the temporal boarders of fundamental processes in chemical physics Ultrafast molecular and cluster dynamics is not limited on the time scale of the motion of nuclei, but is currently extended to the realm of electron dynamics [321]. Characteristic time scales for electron dynamics roughly involve the period of electron motion in atomic or molecular systems, which is characterized by x 1 a.u. (of time) = 24 attoseconds. Accordingly, the time scales for molecular and cluster dynamics are reduced (again ) by about three orders of magnitude from femtosecond nuclear dynamics to attosecond electron dynamics. Novel developments in the realm of electron dynamics of molecules in molecular clusters pertain to the coupling of clusters to ultraintense laser fields (peak intensity I = lO -lO W cm [322], where intracluster fragmentation and response of a nanoplasma occurs on the time scale of 100 attoseconds to femtoseconds [323]. 

Remembering that NMR and X-ray diffraction (XRD) afford complementary information on solid-state dynamics (roughly speaking, NMR measures the depth whereas XRD sees the shape at the bottom of a potential well) and that it is not necessarily true that the flattest well is the shallowest (compare for instance I and II,... 

Micro- and Nanoscale Gas Dynamics Roughness Effect on Microscale Transport w Supersonic Micro-nozzles... 

For diffuse surfaces where the surfaces are thermally mobile, the smearing out of oscillations in the force profile due to the liquid structure may occur. This is the case as the thermal fluctuations make the surface dynamically "rough" at a given instant, although they may be smooth over a time average. Diffuse surfaces include polymers, micelles, bilayers, and emulsions. The short-range... 

Gulliver, J. S. and Song, C. S. S. 1986. Dynamic roughness and the transition between windwave... 

Wettability Wetting dynamics Roughness factor Roughness geometry Drop vibration Metastable wetting state Most stable wetting state Superhydrophilicity... 

The modification of the surface force apparatus (see Fig. VI-4) to measure viscosities between crossed mica cylinders has alleviated concerns about surface roughness. In dynamic mode, a slow, small-amplitude periodic oscillation was imposed on one of the cylinders such that the separation x varied by approximately 10% or less. In the limit of low shear rates, a simple equation defines the viscosity as a function of separation... 

Chandler D 1998 Finding transition pathways throwing ropes over rough mountain passes, in the dark Classical and Quantum Dynamics In Condensed Phase Simulations (Singapore World Scientific) pp 51-66... 

This method has a simple straightforward logic for even complex systems. Multinested loops are handled like ordinary branched systems, and it can be extended easily to handle dynamic analysis. However, a huge number of equations is involved. The number of unknowns to be solved is roughly equal to six times the number of node points. Therefore, in a simple three-anchor system, the number of equations to be solved in the flexibiUty method is only 12, whereas the number of equations involved in the direct stiffness method can be substantially larger, depending on the actual number of nodes. 

Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mosdy in single apphcation niches, unlike workhorse resins such as PVC, phenoHc, urea—melamine, and polyurethane. More expensive engineering resins have a very limited role in the building materials sector except where specific value-added properties for a premium are justified. Except for the potential role of recycled engineering plastics in certain appHcations, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The apphcation content of each resin type is noted in Table 2. Comparative prices can be seen in Table 5. The most dynamic growth among important sector resins has been seen with phenoHc, acryUc, polyurethane, LLDPE/LDPE, PVC, and polystyrene. 

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