Benign environmental effects, including temperature and surface condition changes, can adversely affect the performance of an ultrasonic structural health monitoring system because ultrasonic waves are sensitive to such changes as well as to damage. Compared to temperature, the problem of surface condition changes is more difficult to formalize because of their variability in terms of type, loc...

An epitaxial thin film can undergo surface instability and break up into discrete islands. The stress field and the interface interaction have profound effects on the dynamics of surface evolution. In this work, we develop a nonlinear evolution equation with a second-order approximation for the stress field and a nonlinear wetting potential for the interface. The equation is solved numerically ...

We develop a pore-scale model of wetting in a single fracture. A variable fracture aperture distribution is represented as a square lattice of conceptual pores connected by throats. We borrow concepts from network modeling of ̄ow in porous media to generate a fracture model that includes the e€ects of ̄ow in wetting layers, snap-o€, and cooperative piston-like advance. Cooperative ®lling accoun...

Surface wetting on polyelectrolyte multilayers (PEMs), prepared by alternating deposition of polydiallyldimethylammonium chloride (PDDA) and poly(styrene sulfonate) (PSS), was investigated mainly in water-solid-oil systems. The surface-wetting behavior of as-prepared PEMs was well correlated to the molecular structures of the uncompensated ionic groups on the PEMs as revealed by sum frequency g...

The wetting behavior of quenched-condensed solid D2 films has been investigated by means of light scattering. On the substrates used here (graphite and aluminum) molecular deuterium displays triple point wetting and hence dewets in the solid state, provided the temperature is high enough that thermally activated diffusion processes can take place. This manifests itself in a coarse-graining of t...

The cuticles of most springtails (Collembola) are superhydrophobic, but the mechanism has not been described in detail. Previous studies have suggested that overhanging surface structures play an important role, but such structures are not a universal trait among springtails with superhydrophobic cuticles. A novel wetting experiment with a fluorescent dye revealed the extent of wetting on expos...

This paper discusses a new nuclear magnetic resonance (NMR) method that can provide wettability, saturation, and oil viscosity values in rocks partially saturated with oil and brine. The method takes advantage of two new technological advances in NMR well logging—the MRF* Magnetic Resonance Fluid Characterization Method and NMR “diffusion-editing” (DE) pulse sequences. We discuss the principles...

This study presents a systematic analysis of wetted region due to cooling of aluminum plate by water spray impingement with respect to different water flow rates, spray nozzle heights, and subcooling. Unlike jet impingement, the wetting is not commenced upon spray impingement and there is a delay in wetness of hot test surface. After initiation, the wetting (black zone) progresses gradually to ...

expansive soils show swelling and shrinkage behavior when subjected to cyclic wetting and drying. the variation in water content influence the volume change in this kind of soil. these volume changes can cause ground movement which may result in damage to the buildings and structures. to study the behavior, a number of successive wetting-drying cycles were conducted on a statically compacted ex...