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Primary waves produced by large ships in confined waterways can threaten the sustainability and safety of coastal regions near maritime shipping routes, but the present understanding and predictability of primary wave shallow-water characteristics is hindered by a scarcity of available field observations. This study presents hydrodynamic measurements from 296 primary waves observed in 3.5 to 4.4 m mean water depth throughout four deployments on the channel margins of the Savannah River in Georgia, USA. Ship details and tidally varying waterway parameters are paired with pressure and fluid velocity data to investigate relationships between ship characteristics, waterway conditions, and primary wave magnitudes. Findings show that although larger and faster ships tend to produce larger primary waves, there are inconsistencies among the magnitudes of waves generated by similar ship passages. Additionally, depression prediction equations perform well for most observations, but a small group of "atypically-large" primary waves with depressions exceeding 75 cm are consistently underpredicted and require further investigation. Hydrodynamic, waterway, and ship data are made available in the Supplemental Data. [ABSTRACT FROM AUTHOR]

A flipped classroom approach was implemented in an undergraduate fluid mechanics course. Students watched short, online video lectures before class, participated in active in-class problem solving sessions (in pairs), and completed individualized online quizzes weekly. In-class activities were designed to develop problem-solving skills and teach subject content. The instructor and assistants provided critical "just-in-time tutoring" during the in-class problem solving sessions. Comparisons were made with a simultaneous section offered in a traditional mode by a different instructor. Students in the flipped-classroom section demonstrated greater gains on the Fluid Mechanics Concept Inventory (pre-test versus post-test). Multivariate regression analysis revealed that students in the flipped-classroom section had a significant relative gain on the Fluid Mechanics Achievement Score, which was an aggregative measure of problem solving ability and conceptual understanding. Student feedback on the flipped-classroom section was very positive both in terms of the course format and their perceptions of the amount learned in the course.

The freshwater copepod Hesperodiaptomus shoshone was exposed to a Burgers vortex, a flow feature meant to mimic small‐scale, dissipative turbulent eddies found in the organism's environment, to determine how this copepod responds to microscale turbulent flow structures. Male and female H. shoshone were separately exposed to four turbulence intensity levels plus a negative control (i.e., stagnant flow) in two vortex orientations relative to gravity. H. shoshone demonstrates a mild behavioral change in the presence of a Burgers vortex that is dependent on both sex and vortex orientation. H. shoshone swim with fairly linear trajectories across all four levels of turbulence intensity, which is a notable difference from the swimming behavior of marine copepods exposed to the same flow feature. Variations in morphology, physical environment, or ecological niche between H. shoshone and marine copepods are potential factors that may explain the differences in how the species respond to a Burgers vortex. The setal array of H. shoshone differs from the setal array of the previously studied marine copepods, suggesting differences in sensory ability and response. The small pond habitat of H. shoshone is rarely or intermittently mixed, creating a different hydrodynamic landscape compared to the ocean, which may influence the copepod/turbulence interaction. H. shoshone has few, if any, naturally occurring predators whereas marine copepods have many, which may influence the difference in response to microscale turbulence. [ABSTRACT FROM AUTHOR]

Several species and developmental stages of calanoid copepods were tested for responses to environmental cues in a laboratory apparatus that mimicked conditions commonly associated with patches of food in the ocean. All species responded to the presence of phytoplankton by feeding. All species responded by increasing proportional residence time in one, but not both, of the treatments defined by gradients of velocity or density. Most species increased swimming speed and frequency of turning in response to the presence of chemical exudates or gradients of velocity. Only one species, Eurytemora affinis, increased proportional time of residence in response to gradients in density of the water. Responses of E. affinis to combined cues did not definitively demonstrate a hierarchical use of different cues as previously observed for Temora longicornis and Acartia tonsa. A simple foraging simulation was developed to assess the applicability in the field of the behavioral results observed in the laboratory. These simulations suggest that observed fine-scale behaviors could lead to copepod aggregations observed in situ. The present study demonstrates that behavioral response to cues associated with fine-scale oceanographic gradients and biological patchiness is functionally important and prevalent among copepods and likely has significant impacts on larger-scale distributional patterns.

Previously documented metachrony in euphausiids focused on one, five-paddle metachronal stroke, where contralateral pleopod pairs on the same abdominal segment beat in tandem with each other, propelling the animal forward. In contrast, the mysid shrimp Americamysis bahia 's pleopods on the same abdominal segment beat independently of each other, resulting in two, five-paddle metachronal cycles running ipsilaterally along the length of the body, 180° out of phase. The morphology, kinematics, and nondimensional measurements of efficiency are compared primarily with the one-cycle Euphausia superba to determine how the two-cycle approach alters the design and kinematics of metachrony. Pleopodal swimming in A. bahia results in only fast-forward swimming, with speeds greater than 2 BL/s (body lengths per second), and can reach speeds up to 12 BL/s, through a combination of increasing stroke amplitude, increasing beat frequency, and changing their inter-limb phase lag. Trends with Strouhal number and advance ratio suggest that the kinematics of metachrony in A. bahia are favored to achieve large normalized swimming speeds. [ABSTRACT FROM AUTHOR]

It is shown experimentally that chemical information can be encoded and preserved in flowing liquid streams. It can be retrieved by chemical sensing arrays using correlation analysis. This finding is important for understanding of the mechanism of chemotaxis as practiced by some aquatic animals and also is a necessary prerequisite for construction of chemical plume tracking robots.

Abstract: A new single‐instrument method for removing wave bias from Reynolds stress estimates is proposed. Assuming that the wave motions and the pressure signal are spatially coherent, the method uses a linear filtration scheme to estimate the wave velocity at the instrument based on the pressure signal, and then the estimated velocity is subtracted from the measured velocity to arrive at a wave‐free estimate of the Reynolds stress. The advantage of the proposed single‐instrument technique is that it limits the financial and logistical issues associated with deploying a second instrument. The proposed method is compared to two frequency‐domain‐based single‐instrument techniques and to a two‐instrument method that uses the velocity signal at an adjacent instrument in a linear filtration scheme to estimate and remove the wave velocity. The methods are tested and compared using synthetic time series and field data collected in tidally driven shallow water flow in Wassaw Sound, Georgia and in deeper water currents in Monterey Bay, California. The method proposed in this study offers superior performance over the other single‐instrument techniques in shallow water, comparing favorably with the two‐instrument method. In deeper water, no single‐instrument technique offers clearly superior performance. [ABSTRACT FROM AUTHOR]

A flipped classroom approach was implemented in an undergraduate fluid mechanics course. Students watched short, online video lectures before class, participated in active in-class problem solving sessions (in pairs), and completed individualized online quizzes weekly. In-class activities were designed to develop problem-solving skills and teach subject content. The instructor and assistants provided critical "just-in-time tutoring" during the in-class problem solving sessions. Comparisons were made with a simultaneous section offered in a traditional mode by a different instructor. Students in the flipped-classroom section demonstrated greater gains on the Fluid Mechanics Concept Inventory (pre-test versus post-test). Multivariate regression analysis revealed that students in the flipped-classroom section had a significant relative gain on the Fluid Mechanics Achievement Score, which was an aggregative measure of problem solving ability and conceptual understanding. Student feedback on the flipped-classroom section was very positive both in terms of the course format and their perceptions of the amount learned in the course. [ABSTRACT FROM AUTHOR]

Scientific research regarding fluid flows in curved conduits have been initiated by the pioneering efforts of J. Thomson in 1876 and 1877. Guided by the conjectures made by G.I. Taylor, C.M. White proved that the motion of fluid passing through a helically coiled pipe is laminar below the threshold Reynolds value. This was deduced by through the dye flow visualization technique. Research on transition and reverse transition phenomena and flow configurations are continuously being carried out.