James R. Smith

Bio: James R. Smith is an academic researcher from Research Triangle Park. The author has contributed to research in topics: Wave vector & Wavenumber. The author has an hindex of 1, co-authored 1 publications receiving 73 citations.

Interactions between Steady Won-Uniform Currents and Gravity Waves with Applications for Current Measurements

Abstract: Interactions between steady non-uniform currents and gravity waves are generalized to include the case of a random gravity wave field. The Kitaigorodskii-Pierson-Moskowitz frequency spectrum is used as the basic spectral form for zero current condition. Modified spectral functions in both wavenumber and frequency spaces under the influence of current are found by using energy conservation and kinematic wave conservation laws. The relative importance of the current-wave interaction was measured by the nondimensional parameter U/C0, with U as the current speed and C0 the phase speed of a wave under no current. As a result of the current-wave interaction, the magnitude and the location of the energy peak in the spectrum is altered. Since the phase speed of gravity waves is a monotonically decreasing function of wavenumber and frequency, the influence of current will be predominant at the higher wavenumber range. Furthermore, the contribution from the higher wavenumber range dominates the surface slo...

Interaction of Water Waves and Currents

Abstract: Publisher Summary This chapter discusses the varied physical circumstances in which interactions among water waves and currents occur. Different mathematical approaches, relevant observations, and experiments that are applicable to all or some of these physical circumstances are described. The emphasis is on waves and their interaction with preexisting currents rather than on wave-generated currents. Common simplifying assumption is that the waves are of sufficiently small amplitude for the free-surface boundary conditions to be linearized and evaluated at, or close to, the mean free surface. Most progress can be made in this subject with such a constraint, but wherever possible, finite-amplitude effects are discussed. Unlike some other common forms of wave motion, water waves involve water motion varying with direction perpendicular to the space in which they propagate. The chapter concludes on the interaction of waves generated by a ship with the flow around it.

Distributed sensing of microseisms and teleseisms with submarine dark fibers.

Abstract: Sparse seismic instrumentation in the oceans limits our understanding of deep Earth dynamics and submarine earthquakes. Distributed acoustic sensing (DAS), an emerging technology that converts optical fiber to seismic sensors, allows us to leverage pre-existing submarine telecommunication cables for seismic monitoring. Here we report observations of microseism, local surface gravity waves, and a teleseismic earthquake along a 4192-sensor ocean-bottom DAS array offshore Belgium. We observe in-situ how opposing groups of ocean surface gravity waves generate double-frequency seismic Scholte waves, as described by the Longuet-Higgins theory of microseism generation. We also extract P- and S-wave phases from the 2018-08-19 [Formula: see text] Fiji deep earthquake in the 0.01-1 Hz frequency band, though waveform fidelity is low at high frequencies. These results suggest significant potential of DAS in next-generation submarine seismic networks.

CMS-Wave: A nearshore spectral wave processes model for coastal inlets and navigation projects

Abstract: : The Coastal Inlets Research Program (CIRP) of the U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, in collaboration with two universities in Japan, has developed a spectral wave transformation numerical model to address needs of the U.S. Army Corps of Engineers navigation projects. The model is called CMS-Wave and is part of Coastal Modeling System (CMS) developed in the CIRP. The CMS is a suite of coupled models operated in the Surface-water Modeling System (SMS), which is an interactive and comprehensive graphical user interface environment for preparing model input, running models, and viewing and analyzing results. CMS-Wave is designed for accurate and reliable representation of wave processes affecting operation and maintenance of coastal inlet structures in navigation projects as well as in risk and reliability assessment of shipping in inlets and harbors. Important wave processes at coastal inlets are diffraction, refraction, reflection, wave breaking, and dissipation mechanisms, and the wave-current interaction. The effect of locally-generated wind can also be significant during wave propagation at inlets. This report provides information on CMS-Wave theory, numerical implementation, and SMS interface. A set of examples are given to demonstrate the model's applicability for storm-damage assessment, modification to jetties including jetty extensions, jetty breaching, addition of spurs to inlet jetties, and planning and design of nearshore reefs and barrier islands to protect beaches and promote navigation reliability.

Wave‐current interactions in a wave‐dominated tidal inlet

Abstract: [1] Wave-current interactions play a major role in the dynamics of shallow tidal inlets. This study investigates these interactions at a natural inlet, with a strong focus on current-induced changes on wave propagation. The analysis of hydrodynamic data collected at the Albufeira lagoon, Portugal, revealed spatiotemporal variations of water levels and wave heights along the inlet, attributed to wave-current interaction processes. We compared the simulations of a coupled wave-circulation modeling system, computed with and without waves, and propagated with and without current feedback. The wave-induced setup inside the lagoon represented 7%–15% of the offshore significant wave height. The accuracy of the wave's predictions improved when current feedback was included. During ebb, the currents increased the wave height at the mouth of the inlet (up to 20%) and decreased the wave height in the inlet (up to 40%), due to current-induced refraction, steepness dissipation, and partial blocking. During flood, the currents decreased the wave height in the inlet (up to 10%) and increased the wave height at the exterior parts of the ebb shoal (up to 10%), due to current-induced refraction. These effects significantly attenuate seaward sediment fluxes during ebb and contribute to the sediment accretion in the inlet.