Kelvin-Helmholtz (KH) instability, characterized by the distinctive finite-amplitude billows it generates, is an important mechanism in the development of turbulence in the stratified interior of the ocean. In particular, it is often assumed that the onset of turbulence in internal waves begins in this way. Clear recognition of the importance...
General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular, for precipitation (Intergovernmental Panel on Climate Change, 2013, https://doi .org/10.1017/CB09781107415324.004). Held and Soden (2006, https://doi.org/10.1175/JCLI3990.1) suggest that as lower tropospheric water vapor concentration increases in a...
Multiphase flow dynamics are important in many naval and turbomachinery applications, where bubble interaction with low pressure, vortical structures can lead to undesirable cavitation effects. To better understand the underlying phenomena, a multiscale numerical framework is developed to simulate bubble laden flow in dynamic hydro propulsion systems. Several subproblems in...
Increased temperatures and changes in precipitation will result in fundamental changes in the
seasonal distribution of streamflow in the Pacific Northwest and will have serious implications for water
resources management. To better understand local impacts of regional climate change, we conducted
model experiments to determine hydrologic sensitivities of annual, seasonal,...
Full Text:
. A1),
where variables are similar to those in Eq. 1 except OND, JFM, AMJ, and JAS are the seasons
The Taylor–Goldstein (T–G) equation is extended to include the effects of small-scale
turbulence represented by non-uniform vertical and horizontal eddy viscosity and
diffusion coefficients. The vertical coefficients of viscosity and diffusion, A[subscript V] and K[subscript V],
respectively, are assumed to be equal and are expressed in terms of the buoyancy...
El-Nino Southern Oscillation has many impacts on marine environment. During El-Nino 1997-1998, there has been a change in sea surface temperature in Bali water. Bali water is an important contributor for pelagic fisheries, such as Sardinella lemuru, Thunnus sp, Katsuwonus pelamis, and Euthynnus sp. Sardinella lemuru is emphasized, because the...
Ice–ocean interactions have profound consequences for the ocean and climate, influencing the rate of sea level rise. Submarine melt is commonly parameterized using a three-equation formulation for the heat, salt, and momentum conservation equations coupled to a buoyant plume model, together called plume-melt theory. However, recent direct observations of terminus...
Collisions of counter-propagating solitary waves are investigated experimentally.
Precision measurements of water-surface profiles are made with the use of the laser
induced fluorescence (LIF) technique. During the collision, the maximum wave
amplitude exceeds that calculated by the superposition of the incident solitary waves,
and agrees well with both the asymptotic...
An atmospheric stationary wave teleconnection mechanism is proposed to explain how ENSO may affect the Tibetan Plateau snow depth and thereby the south Asian monsoons. Using statistical analysis, the short available record of satellite estimates of snow depth, and ray tracing, it is shown that wintertime ENSO conditions in the...
Little is known about mixing in the abyssal equatorial oceans in spite of its inferred importance for upwelling dense water. Here we present full-depth microstructure turbulence profiles obtained in the equatorial Pacific that show evidence for intense wind-generated abyssal mixing. Mixing was intensified over the bottom 700 m where the...
Full Text:
-inertial waves on a β-plane, J. Fluid Mech., 684, 111–136,
doi:10.1017/jfm.2011.280.
D R A F T December 7
Little is known about mixing in the abyssal equatorial oceans in spite of its inferred importance for upwelling dense water. Here we present full-depth microstructure turbulence profiles obtained in the equatorial Pacific that show evidence for intense wind-generated abyssal mixing. Mixing was intensified over the bottom 700 m where the...
Full Text:
-plane,
J. Fluid Mech., 684, 111–136, doi:10.1017/jfm.2011.280.
Wunsch, C., and R. Ferrari (2004
Alongshore flow in the direction of propagation of coastal trapped waves can result in upwelling at the shelfbreak. The intensity of this upwelling can be comparable in magnitude to wind-driven coastal upwelling, with its associated ecological features. Recent numerical experiments by Matano & Palma indicate that this upwelling results from...
The semidiurnal mode-1 internal tide receives 0.1-0.3 TW from the surface tide and is capable of propagating across ocean basins. The ultimate fate of mode-1 energy after long-distance propagation is poorly constrained by existing observations and numerical simulations. Here, global results from a two-dimensional semi-analytical model indicate that topographic scattering...
Alongshore flow in the direction of propagation of coastal trapped waves can result in upwelling at the shelfbreak. The intensity of this upwelling can be comparable in magnitude to wind-driven coastal upwelling, with its associated ecological features. Recent numerical experiments by Matano & Palma indicate that this upwelling results from...
In the companion paper (Chen & Yeh, J. Fluid Mech., vol. 749, 2014, pp. 577–596), collisions of counter-propagating solitary waves were studied experimentally by analysing the measured water-surface variations. Here we study the flow fields associated with the collisions. With the resolved velocity data obtained in the laboratory, the flow...
In situ observations of tidally driven turbulence were obtained in a small channel that transects the crest of the Mendocino Ridge, a site of mixed (diurnal and semidiurnal) tides. Diurnal tides are subinertial at this latitude, and once per day a trapped tide leads to large flows through the channel...
A sharp temperature front, oriented along the south-west corner of the leading edge of a Tropical Instability Wave (TIW) warm trough, was encountered at 0°N, 140°W on November 2, 2008 and detected by a 0.45°C increase in SST that occurred over 7 s. The distinct SST signal was observed at...
Tsunami inundation of coastal communities can impose a wide array of forces on the
built environment. Forces generated by tsunami-driven debris damming have the potential to
cause failure of coastal structures and further accumulate flow-entrained debris. Since tsunami-resilient design standards were adopted by ASCE in 2016, debris damming considerations have...
Reed Canarygrass (RCG) is an aggressive invader in aquatic ecosystems that swiftly modifies the environment and decreases biodiversity. A physical model was used to investigate the mechanisms by which RCG spreads. Experimental trials were implemented to examine feedbacks between a mid-channel patch of the flexible RCG, hydraulics, and bedform evolution...
Emerging application areas such as air pollution in megacities, wind energy, urban security, and operation of unmanned aerial vehicles have intensified scientific and societal interest in mountain meteorology. To address scientific needs and help improve the prediction of mountain weather, the U.S. Department of Defense has funded a research effort—the...
Numerous physical and chemical processes are required for successful ignition of a flammable mixture, many of which have been well characterized. However, one aspect of the ignition process that has received limited consideration is understanding the temperature of the spark kernel. A spark kernel is the volume of heated gas...
While the practice of polygyny is common in Ghana, little is known about its impact on the use of reproductive health services. The aim of this study was to assess the relationship between polygynous marriage and the utilisation of skilled antenatal care (ANC), assisted skilled birth, and modern contraceptive services...
The effect of non-zero, but small, viscosity and diffusivity on the marginal stability
of a stably stratified shear flow is examined by making perturbations around the
neutral solution for an inviscid and non-diffusive flow. The results apply to turbulent
flows in which horizontal and vertical turbulent transports of momentum and...
Basin-scale superinertial oceanic tides have been observed globally to resonate with the continental shelf (e.g., the Patagonian Shelf) with a clear theoretical framework. However, the response of the shelf to atmospheric tides – another basin-scale forcing – has not been discussed. This study explores this response using a prominent S2...
Turbulent bottom Ekman layers are among the most important energy conversion sites in the ocean. Their energetics are notoriously complex, in particular near sloping topography, where the feedback between cross-slope Ekman transports, buoyancy forcing, and mixing affects the energy budget in ways that are not well understood. Here, the authors...
This thesis describes the results of a linear stability analysis conducted on a simulated wind-forced ocean front. The ocean surface boundary layer regulates exchanges between the ocean and atmosphere, and the presence of turbulence in the surface layer can greatly impact climate and ocean life. Past research has shown that...
Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for...
The Oregon Multicultural Archives (OMA) at Oregon State University (OSU) is dedicated to preserving and making accessible the histories of traditionally under-represented groups. OMA curator Natalia Fernández and Tiah Edmunson-Morton, the OSU Libraries’ Instruction and Outreach Archivist, highlight three OMA collections that reflect the impact women of color have had...
Increased temperatures and changes in precipitation will result in fundamental changes in the
seasonal distribution of streamflow in the Pacific Northwest and will have serious implications for water
resources management. To better understand local impacts of regional climate change, we conducted
model experiments to determine hydrologic sensitivities of annual, seasonal,...
Full Text:
to December, January to March, April to June, and July to Sep-
tember referred to as OND, JFM, AMJ
A wide variety of hydrodynamic theories are utilized to approximate a Wave Energy Converter’s (WEC) equation of motion. Numerous theories have been refined in order to improve numerical approximations of WEC dynamics. When incorporating refined hydrodynamic theories into numerical models, there are distinct impacts on WEC rigid body motions, cable...
This study investigated spatial-temporal variations of shear stress and bed load transport at three gravel bed river reaches of the Williams Fork River, Colorado. A two-dimensional flow model was used to compute spatial distributions of shear stress (τ) for four discharge levels between one third of bankfull (Qbf) and Qbf....
This article presents the results of a high-resolution (1/12°), two-way nested simulation of the
oceanic circulation in the southwestern Atlantic region. A comparison between the model results and
extant observations indicates that the nested model has skill in reproducing the best-known aspects of the
regional circulation, e.g., the volume transport...
Milk is the first source of nutrition for all mammalian neonates. The complex matrix that constitutes milk has evolved to provide optimal nutrition for the newborn, for each species, respectively. Milk fat, originating in mammary epithelial, forms lipid droplets which are stabilized in the aqueous environment by bioactive polar lipids...
The objectives of this dissertation were to describe the complex oceanographic conditions around the Galápagos Archipelago (eastern equatorial Pacific), their seasonal variability, and their effects on patterns of cetacean occurrence. The physical and ecological factors leading to a plume of high phytoplankton biomass in the wake of the Galápagos were...
Implementing multicomponent diffusion in numerical combustion studies is computationally expensive due to the challenges involved in computing diffusion coefficients. As a result, mixture-averaged diffusion treatments or simpler methods are used to avoid these costs. However, the accuracy and appropriateness of the mixture-averaged diffusion model has not been verified for three-dimensional...
This dissertation studies the coupled fluid-structure interaction (FSI) of a wave energy converter (WEC) and evaluates the design of a WEC mooring system. The research is conducted in support of conceptual development, field test and performance evaluation of WECs as part of the mission of the Northwest National Marine Renewable...
Turbulent flows over rough surfaces are encountered in many engineering and geophysical applications. Flows of this nature, due to their increasing technological interests, have been a subject of rigorous investigation in recent years. Of the particular interest to the oceanographic community is the study of turbulent oscillatory flow over rough...
This thesis assessed the passive, natural circulation, design for a Bi-Ca-CaH2 cooled microreactor based on initial figures of merit. The values for the figures of merit selected for this thesis were: the maximum temperature in the core should not be more than 150 K above the average core outlet temperature,...
Several wave energy converter designs have been recently proposed that are made of flexible materials. Flexible devices are able to generate electricity by being stretched, and are intended to simplify deployment and maintenance concerns over existing wave energy devices. Due to the relative infancy of flexible wave energy converters, however,...
When a few bubbles are entrained in a travelling vortex ring, it has been shown that, even at extremely low volume loadings, their presence can significantly affect the structure of the vortex core (Sridhar & Katz, J. Fluid Mech., vol. 397, 1999, pp. 171-202). A typical Euler-Lagrange point-particle model with...
Interactions and feedbacks among climate change effects and continued human impacts will exacerbate impacts to water resources in complex ways. An urgent imperative of the hydrologic community is to understand the response of hydrologic systems to these perturbations, thus contributing to long-term sustainability of water resources in an uncertain future....
When type inference fails, it is often difficult to pinpoint the cause of the type error among many potential candidates. Generating informative messages to remove the type error is another difficult task due to the limited availability of type information. Over the last three decades many approaches have been developed...
Numerous development projects are implemented in developing countries to attain economic and ecological development. However, in most cases, the encouraging results observed during the implementation phase terminated with the project period, raising concerns on these projects' sustainability after the project period has ended. This study focuses on this sustainability issue...
Monthly temperature and precipitation data from 41 global climate models (GCMs)
of the Coupled Model Intercomparison Project Phase 5 (CMIP5) were compared to
observations for the 20th century, with a focus on the United States Pacific Northwest
(PNW) and surrounding region. A suite of statistics, or metrics, was calculated, that...
Full Text:
regressing winter (January–February–March; JFM)
average temperature and total precipitation against the
The behavior of the thin liquid film formed between a bubble and hydrophobic membrane is of high interest in applications where separating two-phase mixtures is beneficial. One such application is in-situ vapor extraction heat sinks. In these systems, high heat transfer rates are accomplished by taking advantage of the high...
The properties and evolution of nonlinear internal waves (NLIWs) depend
upon the background conditions within which waves form, propagate, and dissipate. As a result, the NLIW field on the New Jersey shelf displayed dramatic variability during the Shallow Water 2006 experiment. Wave variability was exhibited by 1) amplitudes that ranged...
Over recent decades, the Bering Sea has experienced oceanic and atmospheric
climate extremes, including record warm ocean temperature anomalies and marine heatwaves (MHWs), and increasingly variable air-sea heat fluxes. In this work, we assess the relative roles of surface forcing and ocean dynamical processes on mixed layer temperature (MLT) tendency...
We evaluated the relative importance of "bottom-up" (production-limited) and "top-down" (predator-mediated) processes during early marine residence in a population of Chinook salmon (Oncorhynchus tshawytscha) from the upper Columbia River, USA. We examined length, mass, and condition index of age-0 juveniles collected in the ocean during June and September across 11...
Transport phenomena specially the ones that occur in the various engineering disciplines such as tissue engineering and natural environment are often complex to analyze mostly due to the dynamic and geometric complexities; as such, they have been the subject of an active and intense area of research in past decades....
Literature-based review on designing an experimental project regarding placement and orientation of artificial nest boxes related to successful nest box adoption and chick survival in Barn owls within the Willamette Valley.