Flow Environment Research Articles

Prior mapping for nonlinear flows in random environments.

We analyze nonlinear flows in randomly heterogeneous environments, which are characterized by state-dependent diffusion coefficients with spatially correlated structures. The prior Kirchhoff mapping is used to describe such systems by linear stochastic partial differential equations with multiplicative noise. These are solved through moment equations which are closed, alternatively, either by perturbation expansions, or by a posterior linear mapping closure. The latter relies on the assumption that the state variable is a spatially distributed Gaussian field. We demonstrate that the former approach is more robust.

Tectonic and sedimentary evolution of the Korean peninsula: a review and new view

This review focuses on the tectonics and sedimentation of major sedimentary basins and orogenic belts (Late Proterozoic–Neogene) in the Korean peninsula. The Korean peninsula is part of the Amuria Plate and represents an important link between continental blocks of North and South China and the island arcs of Japan. The basement rocks, exposed in the Kyonggi and Yongnam massifs, consist of 2.7 to 1.1 Ga high-grade gneiss and schist. These massifs are separated by the Okchon Fold Belt which comprises metasedimentary rocks and bimodal meta-volcanic rocks. The stratigraphy of the Okchon Group is unclear at present. The Okchon Basin was probably initiated as an intraplate rift prior to the Late Proterozoic. The Hwanggangri Formation (clast-bearing phyllite) most likely represents deposition by subaqueous debris flows in slope environments of an enclosed basin. The stratigraphic relationship between the Okchon Group and the Choson Supergroup (Cambro-Ordovician) of the Taebaeksan Basin is poorly constrained. The Choson Supergroup unconformably overlies the Yongnam Massif and consists mainly of carbonate sequence that formed mostly in shallow marine and tidal environments, reflecting numerous sea-level fluctuations. The sequence is disconformably overlain by siliciclastic sequence of Pyongan Supergroup (Carboniferous–?Triassic) which formed most likely in shallow marine, deltaic, and fluvial environments. The Imjingang Belt is an east-trending fold and thrust zone and consists of metasedimentary rocks and volcaniclastics (Devonian–Carboniferous), underlain unconformably by Proterozoic basement rocks. Late Proterozoic amphibolites of oceanic affinity were metamorphosed at about 8–13 kbar and 630–740°C during the late Permian to the early Triassic. The south-vergent contraction and top-down-to-the-north normal faulting are suggestive of a suture belt between the North China Block (Sino-Korea Craton) and the South China Block (Yangtze Craton), an extension of Sulu Belt across the Yellow Sea. Entire peninsula experienced strong deformation and metamorphism during the suturing event, namely Songrim orogeny. During this orogenic event, the Kyonggi Massif (and the Okchon Basin) accreted to the Yongnam Massif (and Taebaeksan Basin) along the South Korean Tectonic Line running northeast–southwest. A series of northward-trending thrust formed along the boundary zone to the east (Kaktong and Kongsuwon thrusts and others). Piggyback basins locally developed along the thrust faults, forming the Taedong Group. The crustal deformation resumed in the early to late Jurassic (Daebo event) under contractional setting. Dextral ductile shearing associated with thrusting and folding continued in the mid-southern part of the peninsula. It was due to orthogonal (northwestward) subduction of the Izanagi Plate under the Asian continent. The Yongnam Massif experienced continuous dextral offset along the Honam Shear Zone. In the early Cretaceous, the Izanagi Plate began to subduct northward and caused formation of strike–slip basins in retroarc setting, i.e., Kyongsang Basin in the southeastern part and a number of small-scale basins in the mid-southwestern part of the peninsula. Small-scale alluvial fans and fluvial channel networks formed in the basin margin and were transitional to ephemeral lacustrine systems under semiarid to arid conditions. Extensive intrusion of granitoids occurred from Triassic to Early Tertiary with a gap between 160 and 100 Ma, representing continental magmatic arc. In the Tertiary, the southeastern margin of the Korean peninsula experienced back-arc opening. Pull-apart basins formed in the Miocene, bounded by the Yangsan and Hupo faults. The Yonil Group, sedimentary fill of the Pohang Basin, comprises more than 1-km-thick siliciclastic sequence which represents deposition in fan-delta systems on the hanging wall of the Yangsan fault. Thick (more than 10 km thick) sediments in the Ulleung Basin margin were deformed in the late Miocene due to the northward movement of Kyushu Block. Quarternary volcanic events in Cheju Island represent intraplate hot spots.

Counter-Rotating Coupled Drift-Acoustic Vortices in the Presence of Sheared Ion Flows

Nonlinear equations governing the dynamics of finite amplitude drift- acoustic-waves are derived, taking into account sheared ion flows. A new class of stationary solution of the nonlinear equations can be represented in the form of a counter-rotating vortex. The latter appears in those parameter regimes in which the formation of a dipolar vortex is forbidden. For a large perpendicular ion velocity shear parameter, a counter-rotating vortex is similar to a vortex chain. The newly found counter-rotating vortex can be correlated with coherent nonlinear structures that are observed in association with sheared plasma flows in space and laboratory environments.

Long-term flow/chemistry feedback in a porous medium with heterogenous permeability; kinetic control of dissolution and precipitation

The kinetics of dissolution and precipitation is of central importance to understanding the long-term evolution of fluid flows in crustal environments, with implications for problems as diverse as nuclear waste disposal and crustal evolution. The authors examine the dynamics of such evolution for several geologically relevant permeability distributions (models for en-echelon cracks, an isolated sloping fractured zone, and two sloping high-permeability zones that are close enough together to interact). Although the focus is on a simple quartz matrix system, generic features emerge from this study that can aid in the broader goal of understanding the long-term feedback between flow and chemistry, where dissolution and precipitation is under kinetic control. Examples of thermal convection in a porous medium with spatially variable permeability reveal features of central importance to water-rock interaction. After a transient phase, an accelerated rate of change of porosity may be used with care to decrease computational time, as an alternative to the quasi-stationary state approximation (Lichtner, 1988). Kinetic effects produce features not expected by traditional assumptions made on the basis of equilibrium, for example, that cooling fluids are oversaturated and heating fluids are undersaturated with respect to silicic acid equilibrium. Indeed, the authors observe regions of downwelling oversaturatedmore » fluid experiencing heating and regions of upwelling, yet cooling, undersaturated fluid. When oscillatory convection is present, the amplitudes of oscillation generally increase with time in near-surface environments, whereas amplitudes tend to decrease over long times near the heated lower boundary. The authors examine the scaling behavior of characteristic length scales, of terms in the solute equation, and of the typical deviation from equilibrium, each as a function of the kinetic rate parameters.« less

Modeling of Cavitation and Multiphase Flows in Complex Environments

Modeling of Cavitation and Multiphase Flows in Complex Environments

Designing eco-villages for revitalizing Japanese rural areas

Reestablishing a sound environment in rural areas has become one of the most important environmental issues in Japan, not only in rural policy but also in national land policy. Physically speaking, regeneration of natural ecosystems, reestablishment of sound material flows, and the design of rural landscapes are important areas of research and practice. Another important issue in the management of rural areas, particularly in the mountainous areas that cover ∼61% of the country, is the preparation of the landscape for urban dwellers. This paper considers methods for improving rural environments. The modeling of ideal eco-villages with sound natural environment, low input and sustainable material flow, and maintenance of villages through urban and rural interaction is considered. Three different types of typical eco-village models are designed in urban fringe areas, in typical rural areas and in remote mountainous areas. Further, a case-study for the search of reality in adopting such models is surveyed in Chosei-gun, Chiba prefecture as a case of an eco-village in a typical rural areas.

Seasonal rainfall partitioning under runon and runoff conditions on sandy soil in Niger. On-farm measurements and water balance modelling

In sparsely cropped farming systems in semi-arid tropics, rainfall partitioning can be complex due to various interactions between vertical and horizontal water flows, both in the atmosphere and in the soil. Despite this, quantifying the seasonal rainfall partitioning is essential, in order to identify options for increased yields. Results are presented on water flow components, based on field measurements and water balance modelling, for three years (1994–96) in a farmer's field cultivated with pearl millet [ Pennisetum glaucum (L.) Br.] in the Sahel (Niger). Water balance modelling was carried out for three common infiltration categories: runoff producing surfaces, surfaces receiving inflow of runon water from upstream zones, and a reference surface with zero runoff and runon. Runoff was calculated to 25%–30% of annual rainfall (which ranged from 488 to 596 mm), from crust observations, rainfall, soil wetness data, and infiltration estimates. Inflow of runon was estimated from field observations to 8%–18% of annual rainfall. The parameters in the functions for soil surface and canopy resistances were calibrated with field measurements of soil evaporation, stomatal conductance and leaf area. The model estimates of soil water contents, which were validated against neutron probe measurements, showed a reasonable agreement with observed data, with a root mean square error (RMSE) of approximately 0.02 m 3 m −3 for 0–160 cmsoil depth. Estimated productive water flow as plant transpiration was low, amounting to 4%–9% of the available water for the non-fertilised crop and 7%–24% for the fertilised crop. Soil evaporation accounted for 31%–50% of the available water, and showed a low variation for the observed range of leaf area (LAI <1m 2 m −2). Deep percolation was high, amounting to 200–330 mm for the non-crusted surfaces, which exceeded soil evaporation losses, for 1994–95 with relatively high annual rainfall (517–596 mm). Even a year with lower rainfall (488 mm) and a distinct dry spell during flowering (1996), resulted in an estimated deep percolation of 160 mm for the non-fertilised crop. The crop did not benefit from the additional inflow of runon water, which was partitioned between soil water storage and deep percolation. The only exception to this was the fertilised crop in 1996, where runon somewhat compensated for the limited rainfall and the higher water demand as a result of a larger leaf area than the non-fertilised crop.The effects of rainfall erraticness, resulting in episodic droughts, explain why a crop that uses such a small proportion of the available water, in an environment with substantial deep percolation, still suffers from water scarcity. Application of small levels of phosphorus and nitrogen roughly doubled yields, from 380 to 620 kg ha −1, and plant transpiration, from 33 to 78 mm. Evapotranspirational water use efficiency ( WUE ET) was low, 6500–8300 m3 ton-1 grain for non-fertilised crop,which is an effect of the lowon-farmyields and high non-productive water losses. The estimated seasonal rainfall partitioning indicates the possibility of quantifying vertical water flows in on-farm environments in the Sahel, despite the presence of surface overland flow.

Numerical simulations of rotating cooling flows in galaxy cluster environments

We have used 2D numerical simulations to study the evolution of galaxy cluster cooling flows undergoing a rotational perturbation. We show that such rotations in the intracluster medium may arise from cluster/subcluster mergers. Our galaxy cluster initial conditions involve spherically symmetric, steady-state cooling flows with varying mass-dropout strengths. The rotational perturbation serves to break the symmetry for each of the initial cooling flows, resulting in the formation of thin, gaseous disc-like structure extending radially out to ∼10 kpc. Disc-like structure formed for low mass-dropout strength simulations appears to contain cooling condensations whereas disc-like structure in higher mass-dropout strength simulations appears smooth. This is due to the influence of mass-dropout on the degree of cooling, which serves to reduce the strength of thermal instabilities by the removal of ‘cold’ gas from the flow. Morphological comparisons of the disc-like structure formed in our simulations are made to structure observed in the X-ray emitting gas of A4059. Comparisons of the gas dynamics within the disc-like structure are also made to the solid-body rotation profile observed from emission-line gas within the central galaxy of Hydra A. The influence of grid effects on the simulations is also discussed.

Characteristics of the asymmetric circulation associated with tropical cyclone motion

This paper examines the characteristics of the asymmetric flow associated with tropical cyclone (TC) motion using the Final Analysis dataset produced after the Tropical Cyclone Motion Experiment (TCM-90). The wind data vertically-integrated between 850 and 300 hPa around a TC are first separated into an environment flow and a vortex circulation using the filtering algorithm of Kurihara et al. (1995). The latter is then Fourier-decomposed azimuthally to obtain the symmetric and asymmetric components. Nine TCs that occurred during the TCM-90 Experiment are examined.

Heat Flow Visualization and Temperature Measurement of Low-Density Environments using Laser Holographic Interferometry.

Heat flows in low-density environments are generally difficult to visualize using optical methods due to the low refractive index of the medium (air). In this work, we attempt to visualize a temperature field in a low-density environment with the aid of laser holographic interferometry. Low density environments are achieved using natural convection fields under a circular disk cooled by a thermoelectric cooling device which is set in a vacuum-pomp-evacuated chamber. The chamber pressure Pa is varied from Pa&ap;0 Torr to 1 atm. An evaluation procedure for an interferogram is also proposed to estimate local temperatures in the three dimensional axial symmetric field, in which the refractive index depends not only on the temperature, but also the pressure. In the fringe evaluation, the field is divided into equidistant infinitesimal rings where the refractive index is assumed to be constant, and the refractive indices, namely, local temperatures, can then be expressed as a step function of the fringe order shifts.

Cretaceous radiolarian fauna from the Kiselyovsky subterrane, the youngest accretionary complex of the Russian continental far east: Paleotectonic and paleogeographic implications

Abstract The Kiselyovsky subterrane is the northeastern section of the Kiselyovsko‐Manominsky terrane, a distinguishable tectonic unit in the north of the Sikhote‐Alin Range. The terrane has been treated as part of the accretionary wedge belonging to the Khingan‐Okhotsk active continental margin, but its structure and stratigraphy have been poorly understood. This paper presents new data on the subterrane structure, lithology and radiolarian biostratigraphy. The following lithostratigraphic units are established in the terrane: a ribbon chert unit, a siliceous mudstone unit and a elastics unit. Abundant Valanginian to late Hauterivian‐early Barremian radiolarian assemblages are obtained from the upper part of the chert unit in addition to the known Jurassic radiolarians. The radiolarian age of the lower part of the siliceous mudstone unit (red siliceous mudstone) is determined as early Hauterivian‐early Aptian. The unit's upper part (greenish‐gray siliceous mudstone and dark‐gray silicified mudstone) and the clastics unit contain Albian‐Cenomanian assemblages. The arrangement of the units is treated as a chert‐elastics sequence, whose vertical lithologic variations indicate environmental changes from a remote ocean to a convergent margin, reflecting an oceanic plate motion towards a subduction zone. The subterrane structure is a stack of imbricated slabs composed of various lithostratigraphic units, and is complicated by folding. The structure's origin is related to subduction‐accretion, which occurred in the Albian‐Cenomanian. The data presented provide a unique basis for accretionary wedge terranes correlation in the circum‐Japan Sea Region, and the Kiselyovsky subterrane is correlated in this study with the synchronous parts of the East Sakhalin, Hidaka and Shimanto terranes. The Albian‐Cenomanian radiolarian assemblages were deposited in the Boreal realm, while Valanginian ones are Tethyan; this indicates a long oceanic plate travelling to the north. The former assemblages contain an admixture of older species, redeposited by bottom traction currents and turbidite flows in trench environments.

The Use of Liquid Perfluorocarbons for Neonatal Lung Ventilation

Over the last years, physiological studies have proved that ventilation with a oxygenated liquid perfluorocarbon (PFC) provides effective gas exchange and acid base balance and improves lung function and recovery. Low surface tension and high respiratory gas solubility enable adequate oxygenation and carbon dioxide removal at low insufflation pressure. The elimination of air-liquid interfacial surface tension has recently suggested the adoption of total liquid PFC ventilation as an investigational therapy for severe respiratory distress in human infants. This work is aimed to determine the optimal volumes of PFC to be delivered, the frequency of the ventilatory cycle, the oxygen flow rate and the best circuit set up for neonatal application. The optimisation was obtained through the implementation of a simulation mathematical model of oxygen diffusion in a PFC-ventilated lung and of gas exchange between alveolar environment and pulmonary blood flow. The results show that total liquid ventilation is a valid alternative to traditional gas ventilation, particularly when immature neonates with insufficient or absent production of surfactant are concerned.

A REVIEW OF AEROELASTICITY METHODS WITH EMPHASIS ON TURBOMACHINERY APPLICATIONS

This paper is a review of current aeroelasticity methods, with particular emphasis on turbomachinery applications. It also includes a brief survey of the computational fluid dynamics procedures that can be used for the modelling of unsteady flows in such environments. The aeroelasticity phenomena encountered in turbomachinery are introduced from an industrial perspective and the predictive methods are divided into two classes: classical and integrated. The former combine the fluid and structural equations in an uncoupled fashion while the latter attempt to solve the equations together by either exchanging information at each time step or by formulating the aeroelasticity problem in a single unified fluid-structure medium. Further topics, such as the availability of experimental data for model validation, nonlinear structural behaviour, general interblade phase angle, blade mistuning and future directions in aeroelasticity analyses, are also discussed in some detail.

Global Environment and Multiphase Flow. Studies on Dissolution of CO2 in the Ocean.

Theoretical studies of processes for dissolution of CO2at 500-2000m depth in the ocean have revealed a potential of this method as a way to reduce the CO2emissions to the atmosphere, and thus reduce the impacts of such emissions on the global climate and environment. However, complexities associated with the mass transfer of liquid CO2from droplets via hydrate films to dissolution in seawater, as well as the dynamics of buoyant dropletplumes, influenced also by the increase in seawater density due to dissolution of CO2, precludes firm conclusions to be drawn about the vertical distribution of CO2in the water column following injection. Numerical model results indicate that the fate of disposed CO2is strongly dependent on droplet size. If small droplets can be created and maintained, open ocean outlets may become a practical disposal technique. However, the pH of water peeling off from the plume is so low that marine life outside the plume would be adversely affected.

地球環境と混相流 ＣＯ２海洋貯留と混相流

地球環境と混相流 ＣＯ２海洋貯留と混相流

Effects of sediment depositional environment and groundwater flow on the quality of geochemistry of water in aquifers in sediments of Cretaceous age in the Coastal Plain of South Carolina : G. K. Speiran & W. R. Aucott, US Geological Survey Water-Supply Paper, 2416, 1994, 53 pp

Effects of sediment depositional environment and groundwater flow on the quality of geochemistry of water in aquifers in sediments of Cretaceous age in the Coastal Plain of South Carolina : G. K. Speiran & W. R. Aucott, US Geological Survey Water-Supply Paper, 2416, 1994, 53 pp

Slosh wave and geyser excitations due to liquid hydrogen shut-off during draining in microgravity

The dynamical behavior of liquid hydrogen shut-off during draining, and shut-off at the moment of the incipience of a suction dip have been investigated. It shows that a large amplitude surge is observed for liquid in the container at the moment of liquid hydrogen shut-off in reduced gravity. It also shows that slosh waves accompanied by a strong geyser are developed for surge-related flow fields induced by liquid hydrogen shut-off at the incipience of a suction dip. In the slosh wave excitation, both a lower gravity environment and higher flow rate before the shut-off of liquid draining are responsible for the initiation of greater amplitude slosh waves. Slosh wave excitation, due to shut-off during liquid hydrogen draining, shift the fluid mass distribution in the container which imposes time-dependent variation in the spacecraft moment of inertia. This provides important information necessary for on-orbit guidance and attitude control of spacecraft.

A study of middle-high aged impotent patients

Background factors, which are causes of functional and organic impotence, of 729 impotent patients over 50 years old were evaluated. They were classified into 3 major categories, i.e., stresses at job, stresses at home, and diseases or accidents. Over 30% of the patients had 2 or more categories. A retirement from office and troubles at job were most frequent among stresses at job. As to stresses at home, marital problems such as wife's death and remarriage were most common. With respect to diseases or accidents, they were observed in 84 percent of all patients, and hypertension (HT) or diabetes mellitus (DM) were most common and the rate of medication was considerably high. The percent of clearly organic impotence was quite low (22%). Hormonal environment of 303 over 50 aged impotent patients was checked and compared with 120 impotent patients from 20 to 49 years old. Serum testosterone (T) levels in patients over 70 years of age decreased significantly. Lutenizing hormone (LH) and follicle stimulating hormone (FSH) levels in patients after age 50 progressively increased. Patients administered anti-androgenic agenst tended to show lower T and higher LH, FSH, and prolactin (PRL) levels than non-administered. Patients with psychotropic drugs showed significantly higher PRL levels. Hormonal therapy (mainly T replacement therapy) tended to be more effective in patients of low serum T levels before therapy. However, some patients with normal T improved. In 141 impotent patients, 83 cases of which were after age 50, the degrees of their penile arterial impairment were tested using penile brachial index (PBI) and pulse volume recordings (PVR). PVR waveforms were classified into 3 groups, i.e., normal, slightly abnormal, and markedly abnormal. PBI was significantly lower in abnormal groups than in normal group. Between each parameter of PVR and PBI, statistically significant correlation and relevancy were found. Crest time were significantly longer, and PBI and angle of rise significantly lower in over 50 aged patients than in 20-49 aged. We evaluated the risk factors to penile arterial impairment, such as DM, HT, smoking, and cardiovascular disorders. Each of these risk factors was minor to age factor itself. PVR proved to be useful, simple, and non-invasive method for the screening of vascular impotence. In conclusion, degenerative changes occur about hormonal environment and penile blood flow according to aging, and many kinds of background factors have direct or indirect influence to occurrence of impotence. We emphasize such matters should be considered at examination of middle-high aged impotent patients.

高エンタルピ風洞 再突入環境模擬装置と気流計測技術

高エンタルピ風洞 再突入環境模擬装置と気流計測技術

Full inclusion: reality versus idealism.

Topic of Interest: Full Inclusion Parents of both deaf and hearing students request (co-enrollment) placement in greater numbers than can presently be accommodated. Not all children are accepting of the deaf and hard of hearing students . Some make fun of them or do not try to communicate or work together. Full inclusion can be a detriment to all if the hearing-impaired student is not capable of the academic work. Classes where deaf and hearing students are mainstreamed together do tend to move at a slower pace. Communication does require more time for any topic to be taught or discussed, particularly at the beginning of the year. Full inclusion should meet individual needs. It is a plan to coordinate resources, not eliminate them. Parents Observations. In 1992, the parents of 90 hearing, deaf, and hard of hearing students participating in the co-enrollment program were surveyed by mail. About two-thirds were parents of hearing students. Asked about their interest in having their child remain in the program, 87 percent said "yes". The remainder indicated that it didn't matter. The most commonly stated reasons for wanting their child to remain in the program were the social/emotional growth of their child and the fact that their child was happy in the program . Virtually all indicated that their child had both hearing and deaf/hard of hearing friends in school. Of all the comments made by parents , only one was negative. This parent said that she (not her child) thought, "The deaf children in her class are very selfish. They do not click together. My child has a hard time with this because she does not handle rejection very well. It upsets her that the deaf children are not her friends." Many other comments from parents spoke favorably about the social experiences of their children: Because of the socialization at Washington (Elementary School), (he) enjoys the friendships of several hearing boys in his Cub Scout group. We recently had a birthday party at our home. Many of the children were hearing impaired or deaf. It was nice to see all of the children playing together and helping each other. I think they all had something special to offer each other, friendship. I can see hearing children in her class who are eager to learn sign language to make my child feel comfortable and to share with them. (Her) best friend is deaf. She says they play together all the time and are able to communicate with no trouble. ... one of her best friends is hearing . They share their personal likes and dislikes about many things... Before, she was in a hearing-impaired program, it was almost impossible for my daughter to have a hearing friend... (Deaf and hearing ) children were kept apart. That is why the Washington Elementary School program is so important. (She) says that her new friends are friends, and that there is nothing different about them except for how you communicate. In the flow. By its nature, the common "mainstream" or "inclusion" model makes the deaf or hard of hearing student an outsider on the edge of the "mainstream of education ". In contrast, the TRIPOD/BUSD model places the student in the flow of an educational environment which nurtures communication, full participation in learning, and lasting friendships. As stated by a TRIPOD/ BUSD parent, "... they can only learn from each other." Full Inclusion: Reality Versus Idealism Stephen C Baldwin Teacher Texas School for the Deaf The education of deaf students has seen more than its share of movements and controversy over the past several decades, including heated debate over what constitutes the least restrictive environment for educating a deaf child. Now we are confronted with a fireball of a movement called/«// inclusion. In a recent Education section of the New York Times (2/6/94), Albert Shanker, President of the American Federation of Teachers, said: The movement in American education that is taking hold the fastest and is likely to have the profoundest - and most destructive - effect is not what you might think. It's the rush towards full inclusion of disabled children in regular classrooms. Is full inclusion the same old wine as mainstreaming, in...