Visualizing 2D Flows with Animated Arrow Plots

Flow fields are often represented by a set of static arrows to illustrate scientific vulgarization, documentary film, meteorology, etc. This simple schematic representation lets an observer intuitively interpret the main properties of a flow: its orientation and velocity magnitude. We propose to generate dynamic versions of such representations for 2D unsteady flow fields. Our algorithm smoothly animates arrows along the flow while controlling their density in the domain over time. Several strategies have been combined to lower the unavoidable popping artifacts arising when arrows appear and disappear and to achieve visually pleasing animations. Disturbing arrow rotations in low velocity regions are also handled by continuously morphing arrow glyphs to semi-transparent discs. To substantiate our method, we provide results for synthetic and real velocity field datasets

X-ray observations of flow patterns in a mercury boiler

X ray observations of two phase flow patterns in metallic, forced flow mercury boile

The impact of vegetation on fractionation of rare earth elements(REE) during water–rock interaction

Previous studies on waters of a streamlet in the Vosges mountains (eastern France) have shown that Sr and rare earth elements (REE) principally originate from apatite dissolution during weathering. However, stream water REE patterns normalized to apatite are still depleted in light REE (LREE, La–Sm) pointing to the presence of an additional LREE depleting process. Speciation calculations indicate that complexation cannot explain this additional LREE depletion. In contrast, vegetation samples are strongly enriched in LREE compared to water and their Sr and Nd isotopic compositions are comparable with those of apatite and waters. Thus, the preferential LREE uptake by the plants at the root–water–soil (apatite) interface might lead to an additional LREE depletion of the waters in the forested catchment. Mass balance calculations indicate that the yearly LREE uptake by vegetation is comparable with the LREE export by the streamlet and, therefore, might be an important factor controlling the LREE depletion in river waters

Life Cycles of \u3ci\u3eLeuctra Duplicata\u3c/i\u3e and \u3ci\u3eOstrocerca Prolongata\u3c/i\u3e in an Intermittent Streamlet in Quebec (Plecoptera: Leuctridae and Nemouridae)

Large populations of Ostrocerca prolongata and Leuctra duplicata developed in a small intermittent stream in the foothills of the Laurentian Highlands of Quebec. Both species were univoltine in 1974-1975. Ostrocerca prolongata started emerging in mid-to late May. followed by L. duplicata about 2 weeks later. The emergence periods lasted 3-4 weeks with similar patterns in both sexes. Ostrocerca prolongata laid its eggs before the stream dried up in early July. while L. duplicata oviposited just afterward. The eggs of both species did not hatch before October when flow had resumed; the prolonged incubation was due to a diapause in Ostrocerca, but to a depressed development rate in Leuctra. Nymphal growth continued through winter and accelerated considerably in May in both populations. Despite much overlap in timings of the life cycles and in size-frequency distributions of the nymphs. there appeared to be little competition between the two species. probably due to differing food habits

The Streamlet

A song about a stream reflecting a woman\u27s beauty.https://egrove.olemiss.edu/kgbsides_uk/1620/thumbnail.jp

Records on the distribution of Ptychanthoideae (subfam. of Lejeuneaceae, Hepaticae) in Australia

Three species are new for the Northern Territory of Australia: Acrolejeunea securifolia (Nees) Steph. ex Watts ssp. securifolia, Archilejeunea planiuscula (Mitt.) Steph. and Mastigolejeunea ligulata (Lehm. & Lindenb.) Schiffn., and one for Queensland: Thysananthus australis (Steph.) B. Thiers & Gradst. New records of species are given, which were previously known only from one or very few localities, including: Caudalejeunea cristiloba (Steph.) Gradst. and Lopholejeunea plicatiscypha (Taylor) Steph

An Evaluation of Relationships Among Streamflow and Selected Water Quality Parameters in a Forested High-Altitude Watershed

A long-term water quality program has been established at the Noland Divide Watershed (NDW) in the Great Smoky Mountains National Park. The Noland Divide Watershed is a spruce-fir forested catchment which has been shown in previous research to receive some of the largest fluxes of atmospherically-deposited nitrogen and sulfur compounds in the world. Streamwater chemistry data from November 1991 through August 1998 for two streams, the northeast (NE) and southwest (SW) stream, were examined to note results of this deposition on water quality. Automatic monitoring equipment on both streams measure and record pH, conductivity, and temperature readings every 15 minutes, and Stevens recorders in 3-foot H-flumes record stage height which corresponds to a flow rate every 15 minutes. In addition, grab samples were collected weekly and analyzed for pH, conductivity, acid neutralizing capacity (ANC), major anions and cations, aluminum, and silica. Experimental analysis was conducted to describe conditions, detect long-term and/or seasonal trends in water quality, and to relate water quality constituents with the watershed hydrology. In addition, parametric regression models were formed to note influence of several variables such as flow, time, seasonality, pH, and conductivity on analyte loads and concentrations and to test several sampling scenarios that may more-efficiently represent the water quality at NDW. It was determined from the analysis that high flow events are not well represented by the weekly grab samples and therefore water quality during these flow conditions is not fully understood. The SW stream is controlled more by groundwater inputs than is the NE stream, and the water quality characteristics of the two streams are statistically different (p\u3c 0.05) with respect to all analyte concentrations except ammonium. Increased sulfate concentrations (+1.08 μeq/L in SW, +1.32 μeq/L in NE) were observed in the streams for each 1-inch increase of precipitation that occurs since the previous sampling visit. Decreased sulfate concentrations (-0.65 μeq/L in SW and -0.67 μeq/L in NE) were observed in the streams for each 1-day increase in consecutive dry days prior to sampling. Nitrate concentrations observed in the streams were not significantly influenced by precipitation prior to sampling, but decreased concentrations (-0.05 μeq/L in SW and -0.54 μeq/L in NE) were observed for each 1-day increase in consecutive dry days prior to sampling. Parametric regression models show that chloride, sodium, aluminum, and ammonium loads and concentrations are increasing over time, nitrate and silica loads and concentrations are decreasing over time, and sulfate, potassium, and hydrogen ion loads and concentrations are not changing over time. All analyte loads and concentrations except silica are significantly (p\u3c0.10) influenced by seasonality. Parametric regression models also show that grab samples collected on a bi-weekly or tri-weekly frequency would be as statistically adequate for characterizing water quality concentrations and loads as are samples collected on a weekly basis

Two-dimensional unsteady flow visualization by animating evenly-spaced streamlets

Flow visualization has been widely used to display and discover patterns and features in vector fields. Common applications include the representation of ocean currents and weather model data. In this thesis, a flexible method for animating vector fields is developed, based on a generalization of a Poisson disc sampling method. The algorithm has two stages; in the first streamlets are drawn into an image buffer, larger than their intended size. Before they are drawn they are tested to see if they impact on already drawn areas; if they do, they are rejected. In the second stage the ones that pass the test are drawn normal size. The concept of a 3D streamlet object, which groups consecutive time step streamlets as a primitive rendering object, is introduced as part of a method for animating streamlets so that they have minimal overlap and show frame-to-frame coherence providing visual continuity when animating time varying vector fields. Acceptance schemes that allow for occasional overlap between streamlets are explored and found to improve both the speed and the overall quality. Both model data and real weather data are used to evaluate the method. The results show that the method produces good results and is flexible, allows for variable size and density of streamlets, and produces good results