Scattering of dislocated wavefronts by vertical vorticity and the Aharonov-Bohm effect II: Dispersive waves

Previous results on the scattering of surface waves by vertical vorticity on shallow water are generalized to the case of dispersive water waves. Dispersion effects are treated perturbatively around the shallow water limit, to first order in the ratio of depth to wavelength. The dislocation of the incident wavefront, analogous to the Aharonov-Bohm effect, is still observed. At short wavelengths the scattering is qualitatively similar to the nondispersive case. At moderate wavelengths, however, there are two markedly different scattering regimes according to wether the capillary length is smaller or larger than $\sqrt{3}$ times depth. The dislocation is characterized by a parameter that depends both on phase and group velocity. The validity range of the calculation is the same as in the shallow water case: wavelengths small compared to vortex radius, and low Mach number. The implications of these limitations are carefully considered.Comment: 30 pages, 11 figure

Effective viscosity of grease ice in linearized gravity waves

Grease ice is an agglomeration of disc-shaped ice crystals, named frazil ice, which forms in turbulent waters of the Polar Oceans and in rivers as well. It has been recognized that the properties of grease ice to damp surface gravity waves could be explained in terms of the effective viscosity of the ice slurry. This paper is devoted to the study of the dynamics of a suspension of disc-shaped particles in a gravity wave field. For dilute suspensions, depending on the strength and frequency of the external wave flow, two orientation regimes of the particles are predicted: a preferential orientation regime with the particles rotating in coherent fashion with the wave field, and a random orientation regime in which the particles oscillate around their initial orientation while diffusing under the effect of Brownian motion. For both motion regimes, the effective viscosity has been derived as a function of the wave frequency, wave amplitude and aspect ratio of the particles. Model predictions have been compared with wave attenuation data in frazil ice layers grown in wave tanks.Comment: 13 pages, 3 eps figures included; one more section on inertia effect

Poster Session

Advancing Prediction of Headwater Flow Permanence and Stream Expansion and Contraction Using a Process-Based Hydrologic Model Developing ANN Model for Predicting Lake Michigan E.Coli Counts Examining Long Term Trends in Rainfall and Stream Flow at Upper Wabash River Basin Using Self Organizing Map Investigating Water and Sediment Transport Processes with High-Resolution Sensor Measurements and Hysteresis Analysis in the Cane Run Royal Spring Basin, Kentucky, USA Blue Water Farms: Edge-of-Field Water Quality Monitoring of Nutrient and Sediment Loss from No-Till Corn and Soybean Fields in the Lower Cumberland River Watershed Determination of Microcystin Cyanobacterial Toxins in Kentucky Lakes by Diffusive Gradients in Thin Films* Environmental Conditions on the Lower Ohio River with Comments on Phytoplankton Assemblages Restoring Kentucky Streams Containing the Threatened Arrow Darter Comparisons of Conductivity and Chloride Concentrations in the Upper Ohio River Valley During Summer and Winter Months Development and Optimization of Green Polymer and Solvent-Based Ultrafiltration Membranes for Water Treatment Applications Municipal Water Quality Concerns and Rebuilding Trust in a Rural Community Application of a Water Treatment Inspired Technique on a 3D Support for Air Filtration Comparison of Leaf Litter Bag and Environmental DNA in Detection of Salamanders in Maywoods Environmental and Educational Laboratory Reusable Polymeric Sorbents and their Applications in Water Remediation Investigating Plant-Soil Processes and Nitrate Seasonality Using High Resolution Sensors and Stable Isotope Measurements Development and Validation of qPCR Assays for use in eDNA Detection of Ambystoma Species Is Chloride Driving Specific Conductance in Streams in the Upper Ohio River Valley? The Use of Electrical Resistivity Tomography for Delineating Ridgetop Wetland Hydrogeology in the Daniel Boone National Forest in Eastern Kentucky

Proceedings of 2021 Kentucky Water Resources Annual Symposium

This symposium was planned and conducted as a part of the state water resources research institute annual program that is supported by Grant/Cooperative Agreement Number G20AS00025 from the United States Geological Survey (USGS). The contents of this proceedings document and the views and conclusions presented at the symposium are solely the responsibility of the individual authors and presenters and do not represent the official views of the USGS or of the symposium organizers and sponsors. This publication is produced with the understanding that the United States Government is authorized to reproduce and distribute reprints for government purposes. Mention of trade names or commercial products does not constitute their endorsement by the USGS

The westward drift of the lithosphere. A tidal ratchet?

Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth’s geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the ‘westerly’ decoupling of the entire Earth’s outer lithospheric shell and new studies support lower viscosities in the low-velocity layer (LVZ) atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon’s revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle

Study of the dynamic soil-structure interaction of a building on elastic foundation

Tese de mestrado integrado. Engenharia Civil (Especialização em Estruturas). Faculdade de Engenharia. Universidade do Porto. 201

Spatio-temporal correlation of extreme climate indices and river flood discharges

The occurrence of floods is strongly related to specific climatic conditions that favor extreme precipitation events. Although the impact of precipitation and temperature patterns on river flows is a well discussed topic in hydrology, few studies have focused on the rainfall and temperature extremes in their relation with peak discharges. This work presents a comparative analysis of Climate Change Indices (ETCCDI) annual time series, calculated using the NorthWestern Italy Optimal Interpolation (NWIOI) dataset, and annual maximum flows in the Piedmont Region. The Spearman’s rank correlation was used to determine which indices are temporally correlated with peak discharges, allowing to hypothesize the main physical processes involved in the production of floods. The correlation hypothesis was verified with the Spearman’s rank correlation test, considering a Student’s t-distribution with a 5% significance level. Moreover, the influence of climate variability on the tendency of annual maximum discharges was examined by correlating trends of climate indices with trends of the discharge series. These were calculated using the Theil-Sen slope estimator and tested with the Mann-Kendall test at the 5% significance level. The results highlight that while extreme precipitation indices are highly correlated with extreme discharges at the annual timescale, the interannual changes of extreme discharges may be better explained by the interannual changes of the total annual precipitation. This suggests that projections of the annual precipitation may be used as covariates for non-stationary flood frequency analysis

Optimisation of Steel Lazy Wave Risers

Master's thesis in Offshore Technology: Marine and Subsea TechnologyThe objective of this thesis is to optimise the performance of an initial Steel Lazy Wave Riser (SLWR) configuration with regards to the combined loading criteria in the Offshore Standard DNV-OS-F201: Dynamic Risers. This is done by conducting large scale parameter variations for the configuration using the programming interface in the OrcaFlex analysis software. The study considers the implementation of SLWRs in ultra-deep waters, in conjunction with a Floating Production Storage and Offloading (FPSO) vessel. Being connected to a spread moored FPSO in a water depth of 2800 meters, the riser configurations are analysed for typical extreme environmental conditions found in the Santos basin off the coast of Brazil. By analysing the vessel response for different 100-year waves, the worst conditions are determined in terms of the largest downward velocities experienced at hang-off point. These parameters are used in combination with a 10-year current to study the extreme response behaviour for the different configurations analysed. From the design basis, an initial SLWR configuration is established and it is verified that it meets the stated design criteria for combined loading and the wave induced fatigue. This configuration is then subjected to parameter variations by altering the hang-off angle, total net buoyancy force and length of buoyancy section. A total of 75 different configurations are created and analysed under extreme environmental conditions to determine a better configuration in terms of the combined loading utilisation. The findings are presented and a comparison of selected configurations are given to better understand the effect of the parameter variations. The optimisation results show that all the configurations meet the Ultimate Limit State (ULS) design criteria, and that the maximum utilisation experienced in the different cases varies significantly. With tension being the main contributor for the combined loading in these water depths, it is found that a combination of reduced hang-off angle and increased net buoyancy force will improve the performance of the configuration. From the optimisation study, the best configuration is determined and assessed for wave induced fatigue life. The fatigue results show an increase in fatigue life, which also reflects the importance of reducing the top tension. The work presented in this thesis provides information on how different parameters for a SLWR in ultra-deep water affects the combined loading utilisation, and it is proven that this concept is feasible for use in conjunction with a FPSO in these water depths