Showing papers on "Water flow published in 1984"

SUTRA (Saturated-Unsaturated Transport). A Finite-Element Simulation Model for Saturated-Unsaturated, Fluid-Density-Dependent Ground-Water Flow with Energy Transport or Chemically-Reactive Single-Species Solute Transport.

Abstract: : SUTRA (Saturated-Unsaturated Transport) is a computer program which simulates fluid movement and the transport of either energy or dissolved substances in a subsurface environment. The mathematical model employs a two-dimensional hybrid finite-element and integrated-finite-difference method to approximate the governing equations that describe the two interdependent processes that are simulated by SUTRA: (1) fluid density-dependent saturated or unsaturated ground-water flow, and either; (2a) transport of a solute in the ground water, in which the solute may be subject to: equilibrium adsorption on the porous matrix, and both first-order and zero-order production or decay, or, (2b) transport of thermal energy in the ground water and solid matrix of the aquifer. SUTRA provides, as the primary calculated result, fluid pressures and either solute concentrations or temperatures, as they vary with time, everywhere in the simulated subsurface system. SUTRA may also be used to simulate simpler subsets of the above process. Additional keywords: Fluid flow; Radial flow; FORTRAN. (Author)

How Do Benthic Organisms Withstand Moving Water

Abstract: Many aquatic plants and animals spend part of their lives anchored to the substratum as water flows by There are a number of mechanisms by which such sessile organisms can affect the magnitude of the flow-induced forces they encounter, as well as the distribution and magnitude of the mechanical stresses in their bodies produced by those forces Furthermore, the mechanical properties of the skeletal tissues of such organisms affect how much they deform and whether or not they will break in response to flow-induced stresses There are different mechanisms by which organisms can withstand the water flow characterizing a particular type of habitat Biomechanics is a useful tool for studying how the performance of organisms depends on their structure Biomechanical studies should be accompanied by knowledge of the natural history and ecology of the organisms in question if they are to lead to insights about how organisms work

Hydraulic Conductance as a Factor Limiting Leaf Expansion of Phosphorus-Deficient Cotton Plants

Abstract: Suboptimal levels of phosphorus (P) strongly inhibited leaf expansion in young cotton (Gossypium hirsutum L.) plants during the daytime, but had little effect at night. The effect of P was primarily on cell expansion. Compared to plants grown on high P, plants grown on low P had lower leaf water potentials and transpiration rates, and greater diurnal fluctuations in leaf water potential. Hydraulic conductances of excised root systems and of intact transpiring plants were determined from curves relating water flow rate per unit root length to the pressure differential across the roots. Both techniques showed that low P significantly decreased root hydraulic conductance. The effects of P nutrition on hydraulic conductance preceded effects on leaf area. Differences in total root length, shoot dry weight, and root dry weight all occurred well after the onset of differences in leaf expansion. The data strongly indicate that low P limits leaf expansion by decreasing the hydraulic conductance of the root system.

Techniques for Making Finite Elements Competitve in Modeling Flow in Variably Saturated Porous Media

Abstract: A Galerkin finite element formulation is developed for the numerical simulation of water flow in variably saturated soil systems. Included in this formulation is a solution strategy based on Picard and Newton-Raphson algorithms. Both algorithms are designed especially to cope with severely nonlinear field problems. The two algorithms are formulated for both rectangular and triangular elements. The element matrices are evaluated in a simple and efficient manner using a technique referred to as the “influence coefficient” technique. This technique avoids numerical integration and leads to a substantial saving of computational cost. Four examples are presented to demonstrate the effectiveness of the present finite element approach. These examples show that the nonlinear solution schemes are capable of accomodating cases involving large variations in the saturated hydraulic conductivity, as well as highly nonlinear soil moisture characteristics. A comparative study of the Picard and the Newton-Raphson algorithms is also provided. The study indicates that despite the higher cost per iteration of the Newton-Raphson scheme, it usually requires a substantially smaller number of iterations than the Picard scheme. In some instances where convergence difficulties are experienced with the latter scheme, it is desirable to use the Newton-Raphson scheme in order to obtain a cost-effective solution to the problem.

Hydraulic resistance of plants. II: Effects of rooting medium, and time of day, in barley and lupin

Abstract: Barley and lupin plants were grown in pots designed to fit inside a pressure chamber. The pots contained sand, soil, or nutrient solution. Transpiration rates were varied over a wide range. At a given transpiration rate, Q, the balancing pressure, p, of a plant was determined; p is the pneumatic pressure that must be applied to the roots in the pressure chamber to have a cut in the xylem of the shoot on the verge of bleeding. The relation between p and Q, p(Q), was non-linear and hysteretic for solution- grown plants, but was remarkably linear for plants grown in sand or soil, i.e. the data for a given plant on a given occasion conformed closely to the equation p =po + rQ, where po and r were constants. Even though p(Q) was linear for the plants grown in sand or soil, po was often much larger than Δπ, the difference in osmotic pressure between the external solution and the xylem of the root, so that the apparent hydraulic resistance of the plants, i.e. (p-Δπ)/Q, depended strongly on Q. Furthermore, po changed diurnally and was typically 100-200 kPa higher in the afternoon than in the morning. These results are discussed in relation to the equations that are commonly used to describe water flow through plants. It is postulated that r represents the true hydraulic resistance of the plant, which is independent of Q in the plants grown in soil or sand but may vary diurnally, and that the discrepancy between po and Δπ represents either an additional and hitherto unrecognized difference in osmotic pressure across the membranes of the root that intercept the transpiration stream, or a pressure required to open valves through which the water has to pass, with the valves possibly being located in the plasmodesmata.

Flow measuring flumes for open channel systems

Abstract: This book discusses the measurement of open channel flows on a solid scientific foundation by developing sound theory of water flow through long-throated flumes in their numerous shapes (including broad-crested weirs) and facilitates the selection of suitable measuring structures

Improvement of the Probe for Measuring Water Flow Rate in Intact Plants with the Stem Heat Balance Method

Abstract: A probe was improved for measuring the rate of water flow in the stem of intact plants with the stem heat balance method. It consists essentially of flexible flat heater for feeding constant heat energy to a plant stem, heat flow sensing element for determining heat loss from the surface of the heater to the surrounding air and thermocouples for detecting stem temperatures. The improved probe can be easily set and removed to/from the stem and hardly arrests the radial growth of the plant stem. The comparison of the transpiration rate measured by a balance and the water flow rate determined by the new probe showed that the new probe was able to determine the water flux in a thin plant stem with acceptable error which was almost the same level attained with the original measuring device.

Behavior assessment model for trace organics in soil. IV: Review of experimental evidence

Abstract: Experimental evidence supporting the environmental screening model of Jury et al. (1983) is reviewed and discussed. For several laboratory studies of volatilization, initial and boundary conditions matched those used in our model and simulations were run. In all cases, good agreement was found between predicted and measured volatilization losses, with and without accompanying water evaporation. When five chemicals of widely differing volatility were exposed to identical experimental conditions, the model correctly predicted the relative loss behavior observed. The convective mobility predictions of the model were shown to be consistent with several laboratory studies of compound leaching, as long as the water flow rate was slow enough (< 0.01 cm/s) to ensure equilibrium between the solution and adsorbed phases. The Millington and Quirk tortuosity model used in our representation of the soil diffusion coefficient was found to give a good prediction of the water content dependence of the effective diffusion coefficient observed in several studies. The thickness of the stagnant boundary layer predicted from our similarity assumption was shown to be consistent with the apparent thickness inferred from several laboratory and field measurements of volatilization.

Multiple pattern spray nozzle

Abstract: A multiple pattern spray nozzle is provided for connection to a supply of water under pressure, wherein the spray nozzle is adjustable upon movement of a single selector ring to one of several different spray pattern settings. The spray nozzle comprises a nozzle housing for mounting, for example, onto a hose end trigger valve or the like and supporting a stem unit for receiving the supply of water under pressure. A pair of flow control sleeves are carried by a perforate faceplate for sliding movement relative to the stem unit and nozzle housing to define different water flow paths leading respectively from the stem unit to different nozzle outlets formed by the faceplate in cooperation with the stem unit and nozzle housing. The selector ring in turn supports the faceplate and flow control sleeves and is threaded onto the nozzle housing for rotation thereabout to displace the flow control sleeves to select the water flow path and associated nozzle outlet open to water flow, thereby selecting the spray pattern setting. In the preferred form, the selector ring is rotatable to any one of five different setting positions to provide a discharged water stream in the form of a low flow mist, a conical spray, a narrow collimated jet spray, a gentle shower spray, or a generous low-force soaker flow.

Transpiration- and Growth-Induced Water Potentials in Maize

Abstract: Recent evidence from leaves and stems indicates that gradients in water potential (ψw) necessary for water movement through growing tissues are larger than previously assumed. Because growth is sensitive to tissue ψw and the behavior of these gradients has not been investigated in transpiring plants, we examined the water status of all the growing and mature vegetative tissues of maize (Zea mays L.) during high and low rates of transpiration. The ψw measured in the mature regions of the plant responded primarily to transpiration, while the ψw in the growing regions was affected both by transpiration and growth. The transpiration-induced potentials of the mature tissue formed a gradient of decreasing ψw along the transpiration stream while the growth-induced potentials formed a gradient of decreasing ψw from the transpiration stream to the expanding cells in the growing tissue. The growth-induced gradient in ψw within the leaf remained fairly constant as the xylem ψw decreased during the day and was associated with a decreased osmotic potential (ψs) of the growing region (osmotic adjustment). The growth-induced gradient in ψw was not caused by excision of the tissue because intact maize stems exhibited a similar ψw. These observations support the concept that large gradients in ψw are required to maintain water flow to expanding cells within all the vegetative tissues and suggest that the maintenance of a favorable gradient in ψw for cell enlargement may be an important role for osmotic adjustment.

Comparison of calcium and sodium transport in early and late rat distal tubules: effect of amiloride.

Abstract: In vivo tubular microperfusion experiments were performed in rats to compare the function of the early and late rat distal convoluted tubule and to examine the effect of amiloride on distal Na and Ca reabsorption. In clearance experiments, amiloride (6 micrograms/min) reduced fractional Ca excretion (P less than 0.05) and the calcium-to-sodium clearance ratio (P less than 0.001) without affecting fractional Na excretion. The in vivo microperfusion experiments revealed a higher rate of osmotic water flow in late distal convoluted tubules than in early tubules (P less than 0.001), while Na and Ca transport rates were comparable. The addition of 10(-5) M amiloride to the luminal perfusate inhibited net fluid reabsorption (P less than 0.05) and Na reabsorption (P less than 0.01) and enhanced Ca reabsorption (P less than 0.005) in late segments of the distal tubule. The drug did not change early distal function. The degree of enhancement of Ca transport was highly correlated with the degree of inhibition of Na transport, suggesting that the two effects are related. We suggest that increased Ca reabsorption is a result of luminal membrane hyperpolarization or of increased rates of Ca-Na exchange.

Glacier sliding at subfreezing temperatures

Abstract: Nye’s theory of glacier sliding, when modified to incorporate Gilpin’s model of the liquid layer adjacent to foreign solids in ice, predicts non-zero sliding speeds at subfreezing temperatures. Although the predicted speeds are too small to affect glacier motion or even to be observed readily, the total distance of sliding of large glaciers should be adequate to produce bedrock striations. Dissolved solutes in the liquid layer increase the sliding speeds slightly. At temperatures below about – 1° C, 90% of the drag comes from the part of the bed-roughness spectrum at wavelengths between 0.2 and 20 mm regardless of solute concentration. If no more basal ice melts than refreezes (as in a cold glacier), the average liquid-layer thickness and, concomitantly, the sliding speed for given drag and roughness are governed by the ambient temperature. With net melting (as in a temperate glacier), on the other hand, they are governed by the rate of escape of the excess water and no conflict arises between the thickness requirement for run-off water flow and that for regelation water flow. Thus, the proper distinction is not between temperate and cold, but between net melting and no net melting. The theory applies to both cases.

Role of stagnation and obstruction of water flow in isolation of Legionella pneumophila from hospital plumbing.

Abstract: The stagnation of water in two of four hospital hot-water storage tanks found to contain Legionella pneumophila was reduced by keeping the two tanks continually on-line for 1 year. L. pneumophila colony counts in these two tanks fell quickly to low levels, whereas the organisms persisted in the two tanks that were not in use. L. pneumophila continued to be isolated from 50 to 100% of the hospital showerheads which were sampled during this period. We also examined aerators and other hospital faucet fixtures which obstruct water flow. L. pneumophila was isolated from 22 of 30 faucet aerators and 2 of 16 vacuum breakers but not from 26 nonobstructed faucets or 6 backflow preventers. Over a 7-month period, after nine faucet aerators were sterilized, 10 of 60 surveillance cultures revealed L. pneumophila, despite the inability to isolate the organism from the potable-water tanks in use. These data suggest that prevention of stagnation in hot-water tanks may be effective in reducing L. pneumophila concentrations in potable-water systems serving high-risk populations. We have also shown that faucet aerators, by providing a surface for L. pneumophila to colonize, can become secondary reservoirs for the organism in hospital plumbing.

Effect of intake and feeding frequency on feeding behaviour and quantitative aspects of digestion in sheep fed chaffed lucerne hay

Abstract: Chaffed lucerne hay of 64% apparent organic matter (OM) digestibility was fed to wether sheep under four feeding regimens: two levels of dry matter (D.M.) intake (700 (L) and 1050 (H) g/day) and within each level two feeding frequencies (once a day (daily) and once an hour (hourly)). Three separate groups of sheep were used concurrently: a slaughter group was used to obtain feeding behaviour data and to measure pool sizes and obtain samples from the reticulo-rumen; a digestion group, in which each sheep was prepared with a rumen and a duodenal cannula, was used to measure duodenal digesta flow, rumen microbial growth and reticulo-rumen motility; a balance group was used to measure digestibility and nutrient balances.High D.M. intake increased reticulo-rumen pool sizes and flow rates but it did not affect apparent digestibilities or the proportions of OM, fibre, cellulose, hemicellulose, lipid and nitrogen digested in the stomach and intestines. Increased feeding frequency had a major effect on reticulo-rumen pool sizes but did not affect apparent digestibilities or partition of digestion of non-nitrogenous constituents. Daily feeding resulted in increased total-N flow to the duodenum; however, N retention was significantly greater with frequent feeding. It is suggested that this was due to a more efficient tissue utilization of N.The kinetics of digesta flow within the reticulo-rumen, expressed as fractional flow rates, were studied with data from sheep fed hourly. The fractional inflow, outflow and disappearance rates for OM, fibre, cellulose and hemicellulose did not change with an increase in intake because of an equivalent increase in reticulo-rumen volume. Increasing D.M. intake by 50% resulted in a 24% increase in water intake, a 19% increase in reticulo-rumen water volume, and a 49% increase in water outflow rate. The data suggest that the increased outflow of water was achieved by increasing the net flow of water across the mucosa into the reticulo-rumen, rather than by increasing salivation.There was no difference between treatments in the frequency of reticulo-rumen contractions. It was calculated that for each A sequence contraction, OM flow was 0·26 and 0·37 g and water flow was 4·38 and 0·36 g on L and H intakes respectively. A 50% increase in intake resulted in a 42% increase in OM passage per A sequence contraction. This increased passage with intake was not accompanied by an increase in reticulorumen contraction frequency.

Xylem water flow in a crack willow tree (Salix fragilis L.) in relation to diurnal changes of environment.

Abstract: The diurnal course of the xylem water flow in a solitary Salix fragilis L tree in a wet grassland was measured using the tissue heat-balance method There was considerable variation due to meteorological factors Maximum flow rate was 04 kg h-1 m-2 of crown projection area, or 59 kg h-1 kg-1 leaf dry weight The daily total was 24 kg m-2 day-1 or 36 kg kg-1 day-1 Water flow decreased immediately at the tree base and at the branches after start of rain, and in a branch, after cutting it off: the time constant of the system was 600–700 s in both cases The part of the crown oriented to the sun transpired up to ten times as much as the shaded part Over 70% of the total cross-sectional area of the conductive xylem vessels of the trunk was used by the transpiration flow The water content of the trunk tracked the diurnal changes of the xylem water flow rate with a short time-lag During the day, 1% of the trunk volume was temporarily exploited as water reserve, an amount equalling 3% of daily water loss The stereometric configuration of the crown significantly influenced its water loss During the summer period, about 33 mature (polycormic) trees per ha may drain 100% of water consumed by the present-day sedge-grass marsh

Reverse osmosis system

Abstract: A chemically enhanced reverse osmosis water purification system and process is provided in which the inlet of a second reverse osmosis unit is coupled in series to the product water outlet of a first reverse osmosis unit. Water to be purified is conditioned by an ion exchange resin type water softener and pumped to the inlet of the first reverse osmosis unit. The product from the first reverse osmosis unit is treated with a chemical treatment agent, such as a sodium hydroxide solution, upstream of the inlet to the second reverse osmosis unit. The brine from the brine outlet of the second reverse osmosis unit is recirculated to the water flow line upstream of the first reverse osmosis unit.

Water flow and coral colony size: Interhabitat comparisons of the octocoral Alcyonium siderium.

Abstract: Colonies of the octocoral Alcyonium siderium Verrill form aggregations on subtidal vertical rock walls in the Gulf of Maine. Maximum and mean colony sizes increase dramatically from protected embayments to sites exposed to ocean swells and from the bottom to the top of each vertical wall studied. Water movement along the substratum, generated by surface waves and tides, also increases along both gradients. Although plankton concentrations were similar at all sites during a 2-yr period, increased encounter rates of zooplankton with coral tentacles will result in greater energy intake and, thus, faster growth rates at the more exposed sites with greater flow. Other hypotheses for the proximate cause of the size gradient, such as differential mortality of large colonies or generally higher mortality rates at the protected site, are not consistent with available data.

Hydro-current energy converter

Abstract: A hydro-dynamic device for capturing the energy of a natural stream of flowing water, and converting such current or flow of water energy into electric power for user consumption. The device has a primary tubular housing, a sealed, conical, secondary housing mounted within the tubular housing, the secondary housing containing an electrical generator. The secondary housing has a conical end portion, and is disposed within and along the exterior housing longitudinally. A rotor which drives the generator is coupled to the secondary housing, having blades disposed within the path of water entering the primary housing. The interior housing is rigidly mounted to the exterior housing by support panels that also act as guide vanes for the flow of water through the exterior housing over the conical portion of the interior housing, thus increasing water flow velocity. Rigidly affixed toward the rear of said cone are further guide vanes, at an angle approaching forty-five degrees. The rotor has rigidly affixed vanes disposed at approximately forty-five degrees to the rotor. Thus, the flow of water entering the forward portion of the exterior housing is caused to flow over the conical inside housing, and is directed to the vanes affixed towards the rear of the conical inside housing, striking the rotor at an angle of approximately ninety degrees for maximum efficiency, thus turning the rotor and driving the generator. A tertiary housing is mounted inside the exterior housing along the longitudinal axis and at the exit of the exterior housing downstream of the rotor. The end faces of the outer housing include concentric, circular guard panels which are used to prevent entry of foreign objects into the primary housing. Located within the conical housing is another turbine rotor and gearing to ensure that the motor turns at its optimal frequency, regardless of rotor frequency, and fluid that can serve both as lubricant and coolant for the machinery within the secondary housing. The system can be mounted on a platform resting on a sea/river bed, or floated at preselected depths by a floatation system.

The role of capacitance in the water balance of Andean giant rosette species

Abstract: Pith water storage capacity and its role in plant-water relations were studied in seven giant rosette species of the genus Espeletia from the Venezuelan Andes. Readily available water from the pith was calculated to be capable of sustaining mean transpiration for up to 2.5 h. The relative importance of water stored in the pith, however, differed among species. The species that grow in the higher and colder environments tended to have a greater capacitance than the species that grow in the lower and less extreme environments. The pith volume per unit leaf area (PV/LA) was found to be a good indicator of the relative water storage capacity of the adult individuals of each species. Diurnal fluctuations in leaf water potential were not as pronounced in the species with higher PV/LA values. The species-specific PV/LA was highly correlated with the leaf turgor loss point and with the total resistance to water flow from soil to leaves. These results suggested that species-specific capacitance in the genus Espeletia is a response to temperature-limited soil water availability and that cold tropical environments with frequent subfreezing temperatures tend to select for high water storage capacity in giant rosette plants.

Interactions of lysyl-bradykinin and antidiuretic hormone in the rabbit cortical collecting tubule.

Abstract: Although intrarenal infusions of kinins produce diuresis, it is not clear to what extent this response is due to hemodynamically mediated medullary washout and/or to direct epithelial effects of kinins. Recent evidence has shown that bradykinin binds to collecting tubules in vitro. We therefore examined the interactions of lysyl-bradykinin and antidiuretic hormone (ADH) with respect to hydraulic conductivity (Lp) in the rabbit cortical collecting tubule perfused in vitro. To ensure adequate substrate for prostaglandin synthesis, the bath contained 2.5 microM arachidonic acid. Arachidonic acid produced no change in base-line Lp and had no effect on the subsequent response to a supramaximal dose of ADH (100 microU/ml). Therefore, all subsequent experiments were done in the presence of arachidonic acid. Lysyl-bradykinin (10(-9)M) added to either the lumen or bath had no effect on base-line Lp. Collecting tubules which were exposed for 1 h to bath lysyl-bradykinin (10(-9)M) had a significantly diminished subsequent Lp in response to ADH (P less than 0.02). In tubules exposed to bath lysyl-bradykinin plus indomethacin (5 microM), the subsequent ADH response was normal. Lysyl-bradykinin (10(-9)M) added to the lumen had no effect on subsequent ADH response. We conclude that lysyl-bradykinin from the basolateral side inhibits the hydroosmotic response of the cortical collecting tubule to ADH, and that this inhibition is probably prostaglandin-mediated. Lysyl-bradykinin does not affect water flow from the luminal surface. These data indicate that the diuresis seen with kinin infusions may result, at least in part, from a direct epithelial effect. They also suggest a role of the renal kallikrein-kinin system in modulating water transport in vivo.

Microprocessor controlled through-flow electric water heater

Abstract: A through-flow electric water heater has a cannister through which water to be heated flows and in which are disposed a first heating means comprising a plurality of electric heating elements and second heating means comprising at least one electric heating element. A control unit comprising a microprocessor receives a first input signal from a flow sensor and a temperature sensor which sense, respectively, the flow rate and temperature of the water flowing into the cannister and switches the plurality of heating elements of the first heating means on and off in different combination to achieve different heating levels and adjusts the level of heat dissipated by burst firing the at least one heating element of the second heating means to achieve a desired total heating level. A second temperature sensor is provided at the water outlet of the cannister to provide a second input to the control unit to adjust the total heat dissipated by the first and second heating means in response to the first and second inputs to maintain the temperature of the outflowing water constant. The heating elements are each switched on and off by its own solid state switching device (triac) mounted in thermal contact with the cannister to dissipate heat created by operation of the switching device to the water flowing through the cannister. A control panel enables the user to selectively adjust the water flow rate and the outflowing water temperature.

Xylem anatomy, water flow, and hydraulic conductance in the fern cyrtomium falcatum

Abstract: Xylem anatomy and water relations were studied in holly fern (Cyrtomium falcatum, Aspidiaceae) to determine the details of the pathway for water flow through an entire plant and the influence of tracheid number and lumen diameter on water flow. Each leaf has two adaxial traces and an abaxial trace, which are supplied by diarch adventitious roots attached to the dictyostele of the rhizome near the leaf base. Anatomical observations and dye experiments showed that each adaxial bundle vascularizes the approximately seven pinnae on its side of a leaf. An abaxial bundle is intermittently connected to an adaxial bundle as well as other abaxial bundles forming a minor vascular pathway between the bundles of the leaf axis. Changes in both number and diameter of tracheids result in an acropetal decrease in hydraulic conductance per unit length along the rachis, although tracheid number locally increases when the trace for a pinna is produced in an adaxial bundle. Water flow was determined from the transpiration distal to the point in question or by forcing a solution through an axis with applied pressure. The water potential gradient along the plant axis was quite constant, indicating that hydraulic conductance per unit length varied with leaf area to be supplied. About 40% of the overall water potential drop occurred from the rachis into the pinnae, which reflected factors controlling water potential gradients in the lamina and not a very low conductance in the petiolule xylem. Hydraulic conductances calculated using the Hagen-Poiseuille equation and tracheid diameters were generally double those of measured conductances. Since the values tended to vary by a constant factor, tracheid number and diameter may largely control water flow in the xylem.

Measurements of vertical overturns in a stably stratified turbulent flow

Abstract: The vertical overturns occurring behind a biplane grid placed in a continuously stratified water channel were measured with a high‐speed vertical density profiler. The resulting scale (LT)rms, known as the Thorpe scale is compared to the Ozmidov scale LR=(e/N3)1/2 and the Eulerian turbulent scale l=2ρ′/(dρ/dz). For buoyancy‐dominated or stratified turbulence, l and (LT)rms are linearly related, but when all turbulent overturning events have ceased, (LT)rms is shown to decay at a faster rate. Vertical displacements larger than the Ozmidov scale are observed implying that some previously turbulent scales have become fossil turbulence.

Air and water flow in a sealed, ponded vertical soil column: experiment and model

Abstract: Etude experimentale sur l'effet de la pression de l'air sur l'infiltration de l'eau dans une colonne de sol verticale

Water shutoff valve

Abstract: A water shutoff valve is disclosed in the preferred embodiment comprising a cylindrical body having a valve disk and water flow sensor therein. The sensor is operatively connected to a timer which automatically resets to zero upon interruption of water flow through the valve. The valve automatically closes upon continuous flow of water through the valve for a predetermined period of time, indicating a potential leak in the water supply line. The timer may be set for selected time intervals permitting the valve to remain open for short or long intervals as required.

Cuticle, shell porosity and water uptake through hens’ eggshells

Abstract: 1. There was no correlation between water uptake by a warm egg (37 °C) immersed in iced water and the shell's porosity as measured by water vapour conductance. 2. Eggs lacking cuticle on the shell took up more water than those having cuticle. There was no correlation between water uptake and the water vapour conductance of cuticle‐less eggshells. 3. In general there was no correlation between the amount of water taken up by an egg and the weight of cuticle on its shell. With some eggs there was an association between water uptake and the extent of fissuring of the cuticle. 4. It is postulated that the pore canals impede water flow such that osmotic forces acting across the shell membranes do not influence water uptake by eggs.

Self-healing bentonite sheet material composite article

Abstract: The present invention relates to a layered water sealing article of manufacture including a layer of a flexible sheet material adhered to a layer of a composition comprising a non-hydrated water-swellable clay intimately contacted with a polypropene, polybutene, or mixtures thereof particularly useful as a water barrier. The water swellable clay composition can be adhered to the flexible sheet material in any manner, such as by extruding the composition in sheet form onto a layer of sheet material. The clay composition layer is sufficiently tacky to adhere to the sheet material on one major surface, and is sufficiently tacky for adherence to a wall, conduit, floor, roof, or other structure to be protected from water contact, on an exposed major surface in areas of potential water flow to prevent the seepage of water through the bentonite clay composition layer. In one embodiment, the clay composition layer includes a polypropene and/or a polybutene and an elastomer, such as butyl rubber, having sufficient resilience to stretch or expand with the expanding water-swellable clay composition upon hydration and to aid in maintaining the structural integrity and cohesiveness of the clay composition. In another embodiment, the clay composition layer comprises a water-swellable clay, an elastomer, and any plasticizer compatible with the elastomer.

Water Flow Patterns During Prey Capture by Teleost Fishes

Abstract: SUMMARY Water flow into the mouth cavity during suction feeding in centrarchid sunfishes was studied by mapping the trajectories of small particles in the water during prey capture. In Lepomis, a circulation develops as the mouth opens, and water is drawn into the mouth from above, below and in front of the head. Water displaced by movement of the body as the prey is approached during the strike is entrained into the circulation towards the mouth. The parcel of water sucked into the mouth has a diameter approximately one-tenth that of the predator's length.