Internal Water Flow Research Articles

Geophysical methods integration for deep aquifer reservoir characterization and modeling (Sidi Bouzid basin, central Tunisia)

Groundwater resources of the Sidi Bouzid basin (central Tunisia) are hydrogeologically and economically important. This importance is restrained by the complex and poorly understood subsurface geometry of the main basin, the overexploitation of its near-surface aquifers and the lack of deep hydrogeological wells in the study area. To overcome these issues a multidisciplinary study was conducted integrating geological, geophysical, and hydrogeological methods. As the regional structural tendency of the study area is predominated by Atlassic NE-SW trends, gravity anomalies could be defectively interpreted. Thus, different gravity treatments and filters were processed. A residual gravity response of Sidi Bouzid basin was rationally isolated, the main structural features were then outlined and depths of rooted sources were detected. The obtained results are in a good conformity revealing a newly detected sub-horizontal geophysical lineament that seems to be a high zone which may act as a hydrogeological barrier within the investigated basin.Forward gravity modeling supported by 2D seismic reflection data over geological and geophysical methods integration, highlighted the Sidi Bouzid basin subsurface extent. It also defined its thick Tertiary complex substratum and the unknown total thickness and arrangement of its subsurface series. The used approaches provided a depth to basement modeling of the siliciclastic Tertiary complex estimating its depth and disclosing its subsurface configuration and its internal preferential water flow directions. A geophysical basement topography mapping enhancing the subsurface overview was also yielded.

Critical heat flux enhancement by a two-layer structured honeycomb porous plate in a saturated pool boiling of water

In the present paper, we propose a novel critical heat flux (CHF) enhancement technique using a two-layer structured honeycomb porous plate (HPP) that can be applied in principle regardless of heater orientation. In a previous study, the CHF during saturated pool boiling of water was investigated experimentally using an HPP attached to a heated surface and was shown to be enhanced to more than twice (2.0 MW/m2) that for a plain surface. According to the proposed capillary limit model, the CHF can be increased by decreasing the thickness of the HPP because of the decrease in the frictional pressure drops caused by the liquid flow in the porous medium. However, the CHF could not be greatly enhanced when the thickness of the HPP was comparable to the thickness (approximately 100 μm) of the thin liquid film (the macro-layer thickness) formed beneath coalescent vapor bubbles. Based on the observation of the boiling configuration near the CHF, a large coalesced bubble forms on the heated surface and departs periodically. Therefore, the CHF may occur when water contained in a porous material disappears due to evaporation during the bubble hovering period. In order to prevent the dry-out phenomenon during the hovering period of a large coalesced bubble and enhance the CHF, we herein propose that the structure of HPPs should be improved by the superposition of two kinds of HPPs and that each of the HPPs must satisfy two conditions. First, an HPP simply attached to a heated surface should have very fine pores to supply water to the heated surface due to strong capillary action, and the HPPs should be as thin as possible in order to decrease the pressure drop caused by internal water flow. Second, the other HPP, which is stacked on top of the thin HPP, must be structured to hold a sufficient amount of water in order to prevent the inside of the HPP from drying out during the bubble hovering period over the plate. Moreover, for further CHF enhancement, we found that the gap between the HPP and the heated surface caused by the surface roughness is important because vapor escapes through this gap so that liquid is easily supplied to the heat transfer surface.

Energy-saving “NF/EDR” integrated membrane process for seawater desalination. Part II. The optimization of ED process

For the high pressure and high energy consumption of Seawater reverse osmosis (SWRO) desalination technology, an energy-saving “NF/EDR” integrated membrane process for seawater desalination was proposed in our study. The seawater desalination by Nanofiltration (NF) membrane with high desalination capacity has been reported in our previous paper. This manuscript is the second part of this system about the optimization of electrodialysis (ED) process, where ED process with polarity reverse (EDR) was applied to treat the NF output with the conductivity of 8790μS/cm. A series of operation parameters of the ED process were optimized. More specifically, the effects of the concentrate and dilute flow, internal water flow model, as well as temperature of raw water on separation performances were well investigated. Besides, the optimal period of polarity reverse was determined. The results showed that with the dilute stream flow of 150L/h, concentrate stream flow of 120L/h and the ED stack consisted of one stage with two passages, with the proportion of 27/23 in cell pairs, together with suitable raw water temperature, the desalination rate of ED process could be about 90% and the energy consumption was 0.98KWh/(m3 produced water). Furthermore, the membrane fouling could be effectively avoided by EDR with a period of reversing electrodes at 3h. All the results demonstrated that the optimization of ED process is beneficial to the increasing of desalination rate as well as the decreasing of energy consumption in the “NF/EDR” integrated system, besides, it provided research basis and data support for the pilot-scale system of the “NF/EDR” integrated membrane process.

Large-scale study of the effect of wellbore geometry on integrated reservoir-wellbore flow

Extraction of coal seam gas (CSG) prior to mining is crucial for reducing the potential risks of gas outburst and explosions during underground coal mining as well as gas production purposes. Many numerical and experimental studies have been carried out to identify the factors affecting the gas productivity. These factors include coal properties, gas content and wellbore geometries. Two different flow conditions determine the gas production efficiency: The gas flow inside the wellbore injected from wall, and the flow through porous coal medium. The full understanding of simultaneous flow of fluids through reservoir and wellbore is critical for analysing the reservoir behaviour. However, previous studies examined the flow of these fluids separately. In this research, a large scale three-dimensional model for simulation of integrated reservoir-wellbore flow is developed to study the effect of wellbore geometry on flow characteristics and wellbore productivity. Four different wellbore diameters of 0.075, 0.10, 0.125 and 0.15 m as well as three different lengths of 50, 100, and 150 m were chosen to accomplish the parametric study of wellbore geometry. It is assumed that the wellbores were in a steady-state condition for two different single phase scenarios of water and methane gas flow. The simulation results were validated against the pressure drop models for internal single phase gas and water flow reported in the literature. The obtained results revealed that increasing the wellbore diameter led to reduction of fluid pressure in the coal seam. Regarding the effect of wellbore length, it was observed that at a specific distance from wellbore outlet, the pressure distribution is independent of the wellbore length and upstream effects. It is also shown that wellbore production could be enhanced by increasing the diameter and the length of wellbore for both gas and liquid flow. The developed integrated framework can be used further for study of any enhanced gas recovery method by changing the boundary conditions based on the physical model.

Agricultural Virtual Water Trade and Water Footprint of U.S. States

Virtual water transfer in the form of trade in water-intensive crop, animal, and industrial products can constitute a substantial part of the water supply and demand balance of both importing and exporting regions. International studies have identified the United States as the leading gross and net virtual water exporter. This study quantifies water footprints and internal virtual water flows for the forty-eight contiguous states in 2008 by examining the water requirements of eighteen primary water-intensive crops and livestock. States exported 196 and imported 191 billion m3 of water. Iowa, at 14.7 billion m3, leads a collection of eleven states in the North-Central portion of the country with over 4 billion m3 of net exports. Rather than arid Southwestern states, which are collectively slight virtual water exporters, populous states bordering the Atlantic and Gulf coasts were the leading net virtual water importers, led by Florida at 10.8 billion m3. Per capita measures also reflect these general patterns. Virtual water flows are large compared to total water withdrawals, evapotranspiration from rain-fed crops, or total water footprint in nearly every state, with several Eastern states importing roughly half their water footprint and some Midwestern states exporting more virtual water than they withdraw or consume domestically.

Design and study of an electrical liquid heater using conductive polymer composite tubes

This study focuses on both the design and testing of an electrical heating device using current passage tubes made of Conductive Polymer Composites (CPC). To obtain such materials, an insulating polymer matrix is combined with electrical conductive fillers (carbon black, carbon fibres or metal particles). Power dissipation is observed when an electrical current is passed through the charged polymer matrix. To optimise heater design, two different axisymmetric, T(r,z) finite element models were developed with COMSOL®. The first model represents the electro-thermal behaviour of a current passage tube with internal water flow only. The second one takes into account water circulation both inside and outside the heating tube.A prototype was developed based on four immersed CPC tubes supplied electrically and hydraulically in parallel in a PVC casing. The experimental sequences performed on this pilot coupled with a hydraulic circuit made it possible to validate the two models. Analysis of the experimental recordings indicated that thermoelectric efficiency was higher than 90%. The thermal behaviour of such heaters was well defined on the basis of the information obtained from these tests and on the numerical simulations.

Comparison of dry and wet fibre laser profile cutting of thin 316L stainless steel tubes for medical device applications

In medical coronary stent fabrication, high precision profile cutting with minimum post-processing is desirable. Existing methods of profiling thin tubular metallic materials are based mainly on the use of Nd:YAG lasers. In recent studies fibre lasers have been used for stent cutting. However, for profiling thin (<4 mm diameter, < 200 μm wall thickness) stainless steel tubes, back wall impingements often occur. This paper presents a comparison of wet and dry pulsed fibre laser profile cutting of 316L stainless steel tubes. When water flow was introduced in the tubes, back wall damage was prevented. Meanwhile, heat affected zone (HAZ), kerf width, surface roughness and dross deposition have also been improved compared with the dry cutting. The scientific study on the effect of internal water flow on laser cutting of thin tubular stainless steel material is reported for the first time.

The water footprint of Indonesian provinces related to the consumption of crop products

Abstract. National water use accounts are generally limited to statistics on water withdrawals in the different sectors of economy. They are restricted to "blue water accounts" related to production, thus excluding (a) "green" and "grey water accounts", (b) accounts of internal and international virtual water flows and (c) water accounts related to consumption. This paper shows how national water-use accounts can be extended through an example for Indonesia. The study quantifies interprovincial virtual water flows related to trade in crop products and assesses the green, blue and grey water footprint related to the consumption of crop products per Indonesian province. The study shows that the average water footprint in Indonesia insofar related to consumption of crop products is 1131 m3/cap/yr, but provincial water footprints vary between 859 and 1895 m3/cap/yr. Java, the most water-scarce island, has a net virtual water import and the most significant external water footprint. This large external water footprint is relieving the water scarcity on this island. Trade will remain necessary to supply food to the most densely populated areas where water scarcity is highest (Java).

Nonlinear stability of cylindrical shells subjected to axial flow: Theory and experiments

This paper, is concerned with the nonlinear dynamics and stability of thin circular cylindrical shells clamped at both ends and subjected to axial fluid flow. In particular, it describes the development of a nonlinear theoretical model and presents theoretical results displaying the nonlinear behaviour of the clamped shell subjected to flowing fluid. The theoretical model employs the Donnell nonlinear shallow shell equations to describe the geometrically nonlinear structure. The clamped beam eigenfunctions are used to describe the axial variations of the shell deformation, automatically satisfying the boundary conditions and the circumferential continuity condition exactly. The fluid is assumed to be incompressible and inviscid, and the fluid–structure interaction is described by linear potential flow theory. The partial differential equation of motion is discretized using the Galerkin method and the final set of ordinary differential equations are integrated numerically using a pseudo-arclength continuation and collocation techniques and the Gear backward differentiation formula. A theoretical model for shells with simply supported ends is presented as well. Experiments are also described for (i) elastomer shells subjected to annular (external) air-flow and (ii) aluminium and plastic shells with internal water flow. The experimental results along with the theoretical ones indicate loss of stability by divergence with a subcritical nonlinear behaviour. Finally, theory and experiments are compared, showing good qualitative and reasonable quantitative agreement.

Addendum to “An experimental study of the nonlinear dynamics of cylindrical shells with clamped ends subjected to axial flow”

Abstract This paper presents experimental results on the nonlinear dynamics and stability characteristics of thin-walled clamped–clamped circular cylindrical shells in contact with flowing fluid. The experiments were conducted with three experimental set-ups: one for experiments with elastomer shells in annular air-flow, the second for elastomer shells with internal air-flow, and the last one for aluminium or plastic cylindrical shells with internal water-flow. In all cases the interaction between the shell and the fully developed flow gives rise to instabilities in the form of static or dynamic divergence at sufficiently high flow velocities. The aim of the experimental study was (i) to gather data on the critical flow velocity for instability and on the post-critical flow/displacement–amplitude relationship, and (ii) to undertake an analysis of the experimental results and to compare them qualitatively with theoretical predictions. The experimental results show a softening type nonlinear behaviour, with a large hysteresis in the velocity for the onset and cessation of divergence.

An experimental study of the nonlinear dynamics of cylindrical shells with clamped ends subjected to axial flow

This paper presents experimental results on the nonlinear dynamics and stability characteristics of thin-walled clamped–clamped circular cylindrical shells in contact with flowing fluid. The experiments were conducted with three experimental set-ups: one for experiments with elastomer shells in annular air-flow, the second for elastomer shells with internal air-flow, and the last one for aluminium or plastic cylindrical shells with internal water-flow. In all cases the interaction between the shell and the fully developed flow gives rise to instabilities in the form of static or dynamic divergence at sufficiently high flow velocities. The aim of the experimental study was (i) to gather data on the critical flow velocity for instability and on the post-critical flow/displacement–amplitude relationship, and (ii) to undertake an analysis of the experimental results and to compare them qualitatively with theoretical predictions. The experimental results show a softening type nonlinear behaviour, with a large hysteresis in the velocity for the onset and cessation of divergence.

Radial transport of water and abscisic acid (ABA) in roots of Zea mays under conditions of nutrient deficiency

Radial water (J(V)) and abscisic acid (ABA) flows (J(ABA)) through maize root seedlings have been investigated under different conditions of nutrient deficiency. Whereas J(V) was reduced under nitrogen deficiency, potassium deficiency stimulated J(V). A substantial increase of J(ABA) was observed in roots kept under potassium deficiency. The observed changes of J(V) might have resulted from changed barrier properties of the endodermis. Nitrogen and potassium deficiency also caused an accumulation of endogenous ABA in root tissues. Under all conditions studied, except under K(+)-deficiency, external ABA (100 nM) caused an increase of J(V). The data of this study were used to analyse the relations between internal and endogenous root ABA, J(V), and J(ABA). The internal ABA of root tissues was positively correlated with J(V) and was highly significant (P <0.001 for internal and P=0.03 for endogenous root ABA) within the range 2-300 pmol g(-1) FW. It was also highly positively correlated to the radial ABA flows. There was also a highly positive correlation between J(V) and J(ABA). The data of this study indicate, for the first time, the relations between internal ABA, water, and ABA flows. Independent of treatment with external ABA, an ABA transport by solvent drag across the endodermis is confirmed.

Effect of cooling water flow rates on local temperatures and heat transfer of casting dies

In high pressure die casting processes, proper temperature control of a die yields high casting production rates and superior quality components. Die temperature is usually influenced by various die design and process parameters such as size and location of internal water cooling lines, flow rates of cooling lines, and pouring temperature of molten metal. Among them, the cooling water flow rate plays a major role in controlling thermal pattern of the die. In order to better understand the effect of water flow rates on die temperature, a computer-based data acquisition and control system (DACS) has been developed and employed to monitor and record data of internal water flow rates and local temperatures of an industrialized die insert installed in a die casting process simulator. The analysis of experimental information collected by the DACS indicates that the water flow rates influence die temperatures especially at the early stage of die cooling. However, the die heat removal rate tends to decrease as cooling time extends.

The plant response: stress in the daily environment.

Like animals, plants have evolved to survive in almost every climatic and environmental niche available. They have, however, evolved more sophisticated and varied methods to enable them to survive environmental changes in light, temperature, atmosphere composition, water and nutrients and salinity. This, in part, is necessary because of the sessile nature of plants; they do not have the ability to move to more favourable environments. Stress conditions that plants encounter are not always as rare or unusual as we might at first think. The most common environmental variables, necessary for growth, can impose significant stresses on the plant. But should we think of these as unusual and extreme or just part of the normal diurnal responses experienced by the plant? One example is light. While requiring light for photosynthesis and developmental processes, many plants are damaged by excess light, and mechanisms have evolved to dissipate light energy, for example, using metabolites such as flavonoids, which divert electron flow and avoid harmful build up of free radicals. This sensitivity to excess light, sometimes manifest as photobleaching, is not uncommon in plants which have evolved to live in more shaded environments such as the forest understorey, but which have been developed as crop plants in new more open environments. Even plants that continue to live in such shaded conditions have to adapt to sudden high light; sun flecks which occur as upper canopy trees move in the wind can be damaging to plants which are adapted to low light conditions. Again, pigments, such as anthocyanins, a common feature of understorey leaves, are used to deflect damaging energy. The important issue to understand here is that these conditions are not what we might have thought of as extreme, but rather those which occur regularly in any climate. Another good example is high temperature. Leaves generally do not attain temperatures much above 35 oC. They are able to control this by the fact that they can control internal water and air flow, and are not bulky tissues. However, organs such as fruit do not have this same control capacity, and even in temperate climates can attain high temperatures. For instance, an apple growing in an air temperature of not more than 25 oC, as experienced in temperate climates, can reach temperatures of 40 oC−50 oC in the flesh when in direct sunlight (Ferguson et al., 1998). These are temperatures that would be sufficient to inactivate many enzymes in vitro. The flesh temperature of the same fruit may drop to 10 oC −15 oC overnight, representing a possible 30 oC change in temperature in less than 12 h. The process is cyclic, rising and falling each day under normal, temperate, growing conditions. We think of these high temperatures as extreme and the response in terms of stress physiology. However, we should recognize that experiencing and reacting to such conditions is normal, often happens in diurnal cycles, and is part of regular cellular homeostasis. Journal of Zhejiang University SCIENCE ISSN 1009-3095 http://www.zju.edu.cn/jzus E-mail: jzus@zju.edu.cn

305 小型流水バスタブの内部流れに関する研究

305 小型流水バスタブの内部流れに関する研究

Studies of the internal flow process in polymers by 1H NMR microscopy at 500 MHz

Nuclear Magnetic Resonance (NMR) microscopy was used to study the dynamics and diffusion of the internal water flow in erodible Hydroxypropylmethylcellulose (HPMC) and Polyvinylalcohol (PVA) polymers of pharmaceutical interest. Polymers in the form of tablets were hydrated at 37°C continuously and monitored at regular intervals with a 500 MHz NMR microscope. The diffusion and spin–spin relaxation time ( T 2)-weighted images revealed that the gel layer was strongly attached to the core of the tablet in both HPMC and PVA polymers. Spatial distribution of self diffusion coefficients (SDCs) and T 2 of the hydrating polymers were calculated from NMR microscopic images.

5558786 Process for high quality plasma arc and laser cutting of stainless steel and aluminum : Couch Richard W; Sanders Nicholas A; Lu Zhipeng; Luo Lifeng; Stenfelt Staffan C O Hanover, NH, United States assigned to Hypertherm Inc

In medical coronary stent fabrication, high precision profile cutting with minimum post-processing is desirable. Existing methods of profiling thin tubular metallic materials are based mainly on the use of Nd:YAG lasers. In recent studies fibre lasers have been used for stent cutting. However, for profiling thin (<4 mm diameter, < 200 μm wall thickness) stainless steel tubes, back wall impingements often occur. This paper presents a comparison of wet and dry pulsed fibre laser profile cutting of 316L stainless steel tubes. When water flow was introduced in the tubes, back wall damage was prevented. Meanwhile, heat affected zone (HAZ), kerf width, surface roughness and dross deposition have also been improved compared with the dry cutting. The scientific study on the effect of internal water flow on laser cutting of thin tubular stainless steel material is reported for the first time.

A second-order solution of waves passing porous structures

Only linear theoretical analyses of wave interaction with porous structures exist, mainly due to both the complexities of flows inside the porous medium, and the mathematical inhomogeneous boundary-value problem. Since the hydrodynamic flow mechanism is non-linear a non-linear analysis can better describe the characteristic nature of the problem. In this paper, a generalized potential theory is used to describe both the internal and external water flows. An implicit non-linear model is used to describe flow mechanism inside the porous medium. The perturbation method is used to solve the problem analytically up to the second order. The second-order solution is decomposed into time-dependent and time-independent parts. And, correspondingly, the inhomogeneous boundary-value problems are solved analytically. In the analysis, the second-order characteristics of the problem, including the dispersion equation, wave numbers and friction coefficient, as well as wave reflection and transmission, are investigated in detail. It is shown that the mode swapping of the second-order wave numbers only occurs among the evanescent modes. The second-order friction effects become important in shallow-water cases. The comparison of the results of present theory with experimental results shows that the second-order solution is good correction to the linear theory.

Production of Polyethersulfone Hollow Fiber Ultrafiltration Membranes. II. Effects of Fiber Extrusion Pressure (EP) and PVP Concentration in the Spinning Solution

Abstract The dimensional and UF performance characteristics of hollow fiber membranes produced by the solution spinning technique using three polymer solutions (C3, C4, and C5) were studied experimentally. The polymer (polyethersulfone, PES)/solvent (1-methyl-2-pyrrolidone, NMP)/additive (polyvinyl pyrrolidone, PVP) concentration (wt%) used were 20/65/15, 20/60/20, and 25/63/12, respectively, for C3, C4, and C5 solutions, and their corresponding viscosities were 9222, 22,809, and 29,286 cP. The extrusion pressures (EP) used in fiber production were 5 to 15, 20 to 40, and 20 to 60 psig, respectively, for C3, C4, and C5 solutions; the internal coagulant water flow rate (WFR) used were 7.5 and 10 mL/min for C3 fibers, and 5 mL/min for C4 and C5 fibers; and the length of air gap (LAG) was held constant at 80 cm in the production of all the fibers. An increase in EP always tended to increase OD, while ID decreased, increased, or remained constant depending on the WFR used. An increase in PVP concentration in the fiber spinning solution contributed to greater fiber swelling effects. Nascent fiber velocity (NFV) tended to increase with an increase in EP, but it decreased considerably with an increase in PVP concentration in the fiber spinning solution and the consequent increase in solution viscosity. Both fiber dimensions and skin layer morphology were found to be governed by the combined effects of desolvation, fiber swelling, and fiber stretching during fiber production.

Mechanisms of stomatal movement in response to air humidity, irradiance and xylem water potential

Turgor, and osmotic and water potentials of subsidiary cells, epidermal cells and mesophyll cells were measured with a pressure probe and a nanoliter osmometer in intact transpiring leaves of Tradescantia virginiana L. Xylem water potential was manipulated by changing air humidity, light, and water supply. In a transpiring leaf the water potential of mesophyll cells was lower, but turgor was higher, than in cells surrounding the stomatal cavity owing to the presence of a cuticle layer which covers the internal surface of subsidiary and guard cells. Cuticular transpiration from the outer leaf surface was negligibly small. When stomata closed in dry air, transpiration decreased despite an increasing vapor-pressure difference between leaf and air, and the water potential of subsidiary cells dropped to the level of the water potential in mesophyll cells. We suggest that the observed decrease of transpiration at increasing vapor-pressure difference can be attributed to a shortage of water supply to the guard cells from subsidiary cells, causing turgor to decrease in the former more than in the latter. The leafs internal cuticle appears to play a special role in channelling the internal water flow during a water shortage.