Side Of Hill Research Articles

Investigation of wall-function approximations and subgrid-scale models in large eddy simulation of separated flow in a channel with streamwise periodic constrictions

Large eddy simulations are presented for the flow in a periodic channel segment, which is laterally constricted by hill-shaped obstructions on one wall, having a height of 33% of the unconstricted channel. The Reynolds number, based on channel height, is 21,560. Massive separation thus arises on the hills’ leeward sides, the length of which is about 50% of that of the periodic segment. After reattachment, the flow is allowed to recover over about 30% of the segment length before being strongly accelerated over the windward side of the next hill. The principal challenge of this flow arises from the separation on the curved hill surface and the fact that the reattachment point, and hence the whole flow, are highly sensitive to the separation process. Simulations were performed with three grids, six subgrid-scale models and eight practices of approximating the near-wall region in simulations on the two coarser grids. These were supported by wall-resolved and wall-function simulations for fully-developed channel flow. The principal objective is to identify the sensitivity of the predictive accuracy to resolution and modelling issues. Coarse-grid simulations are judged by reference to data derived from two independent highly-resolved simulations obtained over identical meshes of close to 5 million nodes. Similarly, coarser-grid simulations were also performed with the two codes to enhance confidence in the results. The principal message emerging from the simulations is that grid resolution, especially in the streamwise direction around the mean separation position, has a very strong influence on the reattachment behaviour and hence the whole flow. This has serious implications for even more challenging high-Reynolds-number cases in which separation occurs from gently curved surfaces. The near-wall treatment, including the details of the numerical implementation of the wall laws, is also shown to be influential, most prominently on the coarsest grid. The application of the no-slip conditions at the wall at which separation occurs is found to cause substantial errors, especially in conjunction with poor streamwise resolution, even if the wall-nearest grid nodes are within the semi-viscous sublayer, in the range 5≲ y +≲15. The sensitivity to subgrid-scale modelling is shown to be more modest, with those models returning relatively low subgrid-scale viscosity giving the closest accord with the highly-resolved simulation.

Variation in glacial erosion near the southern margin of the Laurentide Ice Sheet, south-central Wisconsin, USA: Implications for cosmogenic dating of glacial terrains

We measured the abundance of cosmo- genic 10 Be and 26 Al in 22 samples collected from five striated granite, metarhyolite, and quartzite outcrops in south-central Wiscon- sin that were covered by the late Wisconsin Laurentide Ice Sheet. In two outcrops, mea- sured nuclide abundances are consistent with the existing radiocarbon chronology of ice retreat. In three outcrops, nuclide abun- dances were up to eight times higher than predicted by the radiocarbon chronology. At these three sites, several thousand years of ice flow eroded only centimeters to deci- meters of rock, allowing a significant quan- tity of nuclides (10 5 two samples carry the equivalent of .150,000 yr of surface exposure, even though they were covered by ice during the last-glacial-maximum advance. Samples highest on the landscape or in plucked ar- eas have less inheritance than those from the lee sides of large hills or lower in the landscape. Three quartzite samples collect- ed ;10 km up-ice from the margin contain three to four times the expected nuclide abundance (10 5 to 10 6 atoms per gram of quartz). In contrast, eight other quartzite and granite samples from two outcrops .50 km up-ice from the former margin contain only 10 5 atoms of 10 Be per gram of quartz, consistent with late Pleistocene ex- posure and little, if any, nuclide inheri- tance. This relationship between glacial erosion and distance from the former ter- minus is consistent with a marginal zone of minimal subglacial erosion; the ice was ei- ther frozen to its bed there, or the ice thick- ness and duration of ice cover were less near the terminus. These data, together with simple model- ing of nuclide production by deeply pene- trating muons, suggest that many meters of rock must be removed to reduce inheri- tance to negligible levels (,1000 yr) in con- tinental terrains with low long-term erosion rates. Our results indicate that cosmogenic dating of exposed bedrock surfaces near former ice margins or in areas where ice was frozen to the bed may be uncertain, and in some cases impossible, because nu- clides are inherited from prior periods of cosmic-ray exposure. Unfortunately, striat- ed glacial outcrops that can be used to dem- onstrate most easily the assumption of ''no postglacial erosion'' are also the most likely to have undergone little glacial erosion. This finding suggests that cosmogenic- nuclide production rates based on glacially striated surfaces may include cosmogenic nuclides inherited from prior exposure.

Airbone particles dynamics: Towards a theoretical approach

Wind-tunnel simulations and field experiments for dust transport by air show that deposition is predominant on the windward side of hills whereas sans deposition is mainly observed on the lee side. That and other aspects such as the existence of several deposition regimes depending on wind intensity call for theoretical explanations. We present some preliminary considerations leading to such a theoretical framework.

The Effect of Bottom Topography on the Speed of Long Extratropical Planetary Waves

Abstract This paper examines how slowly varying topography induces changes in all aspects of long planetary wave propagation, including phase speed and surface signature, through steering effects. The approach introduces a method for the exact solution of the vertical topographic eigenvalue problem for arbitrary realistic stratification and ray theory in the horizontal. It is shown that, for observed stratifications, first internal mode topographic waves have phase speeds between about 0.4 and twice the local flat-bottom phase speed. Increases occur on the western and equatorward sides of hills. Focusing of ray trajectories and caustics are common features of the solutions. Despite a bias between slowdown and speedup, on average there is little speedup except in high latitudes (where long-wave theory is less applicable). Calculations are performed for five main ocean basins, assuming waves are generated at the eastern coastline, using smoothed topography. These calculations confirm the above findings: the...

Genotype × environment interactions for early growth and ultrasonic measurements in hill sheep

AbstractGenotype × environment and genotype × sex interactions were investigated using lines of Scottish Blackface sheep that had been divergently selected under intensive husbandry conditions for predicted carcass lean proportion, and offspring of rams from these selection lines which were reared under extensive hill conditions. Traits considered were live weight and ultrasonic fat and muscle depth. These were measured at 20 weeks of age on the intensively reared lambs and at 17 weeks of age on the extensively reared animals. Heritabilities for the two environments were 0-39 and 0-20 for fat depth, 0-36 and 0-25 for muscle depth and 0-23 and 0-12 for live weight. Genetic correlations between the environments were 0-54 (s.e. 0-17), 0-90 (s.e. 0-14) and 0-11 (s.e. 0-43) for fat depth, muscle depth and live weight, respectively. The extensive environment may be subdivided according to whether the lambs are reared on improved pasture or on the hill side. The genetic correlations (with s.e.s where estimable) between performance in these two environments were 0-70 (s.e. 0-33), 0-71 (s.e. 0-23) and 1-00 for fat depth, muscle depth and live weight. Genetic correlations between male and female performance under extensive conditions were 0-84 (s.e. 0-28), 0-99 (s.e. 0-14) and 1-00 for fat depth, muscle depth and live weight. T-or fat depth, the genetic correlations of the intensively reared lambs (males only) with extensively reared females and males were 0-37 (s.e. 0-22) and 0-67 (s.e. 0-17), respectively.

Vorticity Transport Analysis of Turbulent Flows

Turbulence closure for the Reynolds averaged Navier-Stokes equations based on vorticity transport theory is investigated. General expressions for the vorticity transport correlation terms in arbitrary two-dimensional mean flows are derived. Direct numerical simulation data for flow in a channel is used to evaluate the modeled terms and set unknown scales. Results are presented for a channel, flat plate boundary layer, and flow over a hill. The computed mean flow and kinetic energy compares well with numerical and physical experiments. The vorticity transport model appears to perform better than conventional Boussinesq eddy viscosity Reynolds stress models near the separated flow region on the leeward side of the hill.

Chromosome Numbers for Three Mosses from Subantarctic Macquarie Island

Chromosome numbers are recorded for the first time for three moss species from Macquarie Island. They are the first reports worldwide for Notoligotrichum australe (Hook. f & Wils.) G. Smith n = 7, and Muelleriella crassifolia (Hook. f & Wils.) Dus. subsp. crassifolia n = ca 36, while the chromosome number n = 26 for Pottia heimii (Hedw.) Hampe confirms previous reports for this species. Subantarctic Macquarie Island, (54*30'S, 158*57'E) politically part of Tasmania, Australia, is located about 1,000 km southeast of Tasmania. Macquarie Island is oceanic in origin, an emergent portion of the ocean floor and a crest of the Macquarie Ridge. is geographically isolated, with a cool harsh climate that is relatively uniform throughout the year and buffetted by incessantly strong westerly winds. The island is elongate, 34 km long and up to 5.5 km wide and almost rectangular. It consists of an undulating plateau more than 200 metres above sea (Selkirk et al. 1990). Geographical isolation and the prevailing climate have limited the diversity of vegetation. Neither trees nor shrubs occur. Bryophytes, lichens, and lowgrowing vascular plants are important components of the vegetation. Bryophytes are found from sea level to the highest altitude (433 m) and in all habitats. In some vegetation types such as mire or feldmark, bryophytes may be the dominant component. The bryophyte flora includes some 80-85 moss species and about 50 hepatics (Selkirk et al. 1990). Many bryophytes are sterile, reproducing only asexually (Bergstrom & Selkirk 1987). MATERIALS AND METHODS Moss specimens bearing capsules were collected by D. M. Bergstrom from Macquarie Island in October 1984. These were maintained under cold conditions similar to that on the island and examined for meiosis. These were stained in aceto-carmine then slides made permanent after freezing on dry ice and mounting in euparal (Ramsay 1983). Voucher specimens are at NSW. Specimens examined. -Notoligotrichum australe--on track in exposed feldmark east of Prion Lake, 200 m elev., Ramsay 118/84; on peat exposure between overland track and Red River, 150 m Elev., Ramsay 115/84; 150 m contour mark on overland track, NW of overland track and Brothers track junction in gravel/peat Ramsay 116/ 84). Pottia heimii-in runoff area directly N of ANARE Station, 0.5 melev., Ramsay 114/84; 119/84. Muelleriella crassifolia on rock in coastal tussock SW side of Wireless Hill, 5.0 m elev., Ramsay 117/84. RESULTS AND DIScuSSIoN Chromosome numbers were obtained here for three moss species on Macquarie Island, one in each of the families Polytrichaceae, Pottiaceae, and Orthotrichaceae. The only previous chromosome count for a moss on Macquarie Island is n = 10 for Bryum argenteum cited in Seppelt and Selkirk (1984). A number of cytological studies of other subantarctic and antarctic mosses have been reported (Inoue 1976; Newton 1980; Ochyra 1985; Przywara et al. 1984). Polytrichaceae. --Notoligotrichum australe (Hook. f. & Wils.) G. Smith, n = 7, Fig. 1-4. Notoligotrichum australe is one of three members of the Polytrichaceae on Macquarie Island where it is widely distributed occurring often on gravelly substrates. also occurs along the southeastern tablelands of the Australian mainland and in Tasmania (Scott & Stone 1976; Streimann & Curnow 1989). There are no previous reports of a chromosome number for N. australe, but the chromosome number for two subantarctic species (as Psilopilum antarcticum (C. Muell.) Par. and P. trichodon (Hook. f. & Wils.) Mitt.) is n = 7 (Fritsch 1991). The chromosome number n = 7 (Fig. 1-3) was obtained for collections of N. australe from three separate localities. The sporocytes are relatively small, as are all Polytrichaceae when compared to other mosses. At metaphase I of meiosis the seven bivalents included three large and four smaller ones (Fig. 1, 2, 4). Early separation of some bivalents, 0007-2745/95/359-362$0.55/0 This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:33 UTC All use subject to http://about.jstor.org/terms 360 THE BRYOLOGIST [VOL. 98

Arracacia ravenii (Apiaceae), a New Species from Southern Mexico

A new species of Arracacia (Apiaceae) is described from the high mountains of Chiapas and Oaxaca, Mexico. Although sharply distinct in many respects, it is contrasted with A. pringlei J. Coulter & Rose, the Oaxacan taxon it most closely resembles. Arracacia Bancroft is one of the largest and most important apioid genera of Umbelliferae in the New World, not least because some of its members served as important food plants for the Incas. The genus is central to a number of other Mesoamerican genera, such as Tauschia, Coaxana, Coulterophytum, Myrrhidendron, and Neonelsonia, all of which have been confused with it in one way or another. It continues to yield well-marked but previously undescribed forms from throughout its extensive range. Attention is called to the following example to facilitate its inclusion in Flora Mesoamericana. Arracacia ravenii Constance & Affolter, sp. nov. TYPE: Mexico. Chiapas: Municipio de Tenejapa, steep heavily wooded slope of Cerro Zontehuitz, with Quercus, Drimys & Magnolia on NE side of hill, paraje of Matsab, alt. 9200 ft. (2804 m), 25 Aug. 1966, D. E. Breedlove 15311 (holotype, DH; isotype, UC). Figure la-f. Species Arracaciae pringlei J. Coulter & Rose affinis sed habitu procumbenti, non glauco-caulibus, divisionibus foliorum confertis acutis non acuminatis, pedunculo solitario terminali, involucello evidenti, floribus flavo-virentibus, fructibus late ovoideis differt. Slender, caulescent, branching, woody-based perennial herbs forming trailing mats to 60 cm long, the foliage glabrous, the inflorescence scaberulous; leaves triangular-ovate, 5-15 cm diam., ternatebipinnate or 2-3-pinnately dissected, the ultimate divisions oblong-ovate to lanceolate, 5-15 mm long, 1-10 mm broad, crowded, sessile, acute, spinuloses rrate and pinnately incised toward base, the uppermost confluent, conspicuously reticulate, squamosely tufted on the rachis above, a well-defined nodal ring lacking; petiole 5-10 cm long, oblongsheathing; cauline leaves numerous, like the basal; inflorescence of a solitary rather stout terminal peduncle 10-20 cm long; umbels 8-12 cm diam.; involucre lacking, or of inconspicuous filiform bracts; rays 12-18, mostly fertile, slender, 3.5-5 cm long, subequal, slightly webbed; umbellets 30-40-flowered, the 2-8 fertile pedicels slender, 5-10 mm long; involucel of 5-8 linear-lanceolate, scariousmargined, acuminate bractlets to 10 mm long, equaling flowers but shorter than fruit; flowers greenish yellow, the petals oval; stylopodium conical, the styles slender; carpophore apparently bipartite; fruit broadly ovoid, 4-5 mm long, 3-4 mm broad, glabrous, tapering at apex, the ribs very prominent; vittae large, usually solitary in intervals, 2 on commissure; seed channeled under intervals, the face sulcate; chromosome number unknown. Distribution. Known only from mountains of central Chiapas (Cerro Zontehuitz) and southern Oaxaca (Cerro Zempoaltepetl). Habitat. Steep slopes with Quercus, Drimys, Magnolia, Ilex, and Podocarpus, in wet montane or cloud forest, at 2400-3000 m. Arracacia ravenii keys readily to the group of woody-based species comprising A. fruticosa Rose, A. ebracteata (Rose) Mathias & Constance, A. aegopodioides (Kunth) J. Coulter & Rose, and A. pringlei J. Coulter & Rose, more particularly the last. It differs from A. pringlei in its sprawling habit, green rather than glaucous stems and rachises, crowded leaf divisions, solitary terminal peduncle rather than terminally clustered peduncles, evident involucel, yellowish green rather than purple flowers, and broadly ovoid rather than oblong-fusiform fruit. We are pleased to name the plant for Peter Raven, who, among so many other accomplishments, played a very significant role in initiating the Flora of Chiapas project. NovoN 5: 22-23. 1995. This content downloaded from 157.55.39.163 on Sat, 19 Nov 2016 04:22:51 UTC All use subject to http://about.jstor.org/terms Volume 5, Number 1 Constance & Affolter 23 1995 Arracacia ravenii

Preliminary analysis from rapid-fire experiment over Whiskey Hole; ARSRP ’93

This paper presents a preliminary analysis of the rapid-fire data taken over Whiskey Hole during the Cory ’93 cruise. The data were collected at 90-s ping intervals to investigate variability between pings and to map the basement under the Whiskey Hole sediment pond. Analysis shows that the sediments at this site have a maximum thickness of 150 m. Over a range of grazing angle 30°<γ<90°, attenuation due to the sediments is modest, maximum of 3 dB, both over the pond and on the hill sides surrounding the pond. Heterogeneity of the sediments is unimportant. Surface waves effects are not seen in the data, which is discrete in both cross and along track directions. A scatterer density of O(10) per square kilometer is estimated with an average lineal spacing between scatterers of 250 m. Most of the data observed are vertically propagating multipath reverberation. In a small window near the beginning of the record direct scatter is seen. Also, occasionally in the late-time record a few high-energy direct scatter events are seen punching through the reverberant noise floor. [Work supported by ONR.]

Regulation of the environmental impacts of coal mining in the USA

Decades of environmentally unregulated coal mining in the USA have resulted in thousands of polluted streams, contaminated groundwater aquifers, subsidence effects, scarred hill sides and massive waste dumps. Similar environmental damage due to coal mining has occurred in Eastern Europe. In the USA, to correct the environmental damage due to coal mining, the Surface Mining Control and Reclamation Act was passed in 1977. This paper examines the provisions of the Act in detail and ends with a warning to the Eastern European countries. ‘The lessons to he learned from the US experience may be reduced to one essential observation: unregulated coal mining in a free market economy can cause extremely serious environmental harm with attendant adverse social and economic impacts which cannot be effectively resolved without comprehensive and strict governmental regulation’.

Giant urban cavern stretches existing soft ground limits : Wallis, S Tunn TunnlgV22, N6, June 1990, P19–22

The NATM, known as the shotcrete method in Southern Germany, is being used to excavate a 180m long 250 square metre cross section cavern for an underground car park into the side of a steep hill in an urban area of the historic town of Landsberg near Munich. Financial aid for the expensive project was given by the Federal Government because the car park is adapted to provide a civil defence shelter for 5000 people and the scheme also improves an inner city centre. All the property above the cavern, some of which is due to be demolished for redevelopment, is owned by the local council. The project was complicated by the need to locate and seal off a collapsed 1944 civilian bomb shelter close to the cavern zone. Extensive monitoring of the surface levels above the excavation showed that surface settlement on opening up the crown top heading following full excavation of the two side wall drifts was around 15mm, much less than the 25mm predicted. Excavation of the 4m deep invert will be undercut from the far end of the cavern back towards the main entrance and the interior concrete construction for 345 cars on three floors will be from the base up. The cavern will be finished by a 45cm thick lightly reinforced concrete lining, any water ingress will be pumped out from a central sump drain. (TRRL)

Landing Places of Migratory Planthoppers, Nilaparvata lugens (STÅL) and Sogatella furcifera (HORVATH) (Homoptera : Delphacidae) in Japan

Migratory planthoppers, Nilaparvata lugens (STÅL) and Sogatella furcifera (HORVATH), both migrate from abroad to Japan every year. Tsubo is the term used for lowland paddy fields where the planthoppers usually make their first landing. In order to identify and examine the general features of Tsubo, a nationwide questionnaire survey was conducted in 1986 and 1987. Two typical types of Tsubo were identified by topographical conditions and wind direction. One type is located on the east side of hills sheltered from westerly winds and is generally found along the coast. The other type is located at the end of valleys facing windward. Migration of planthoppers to Japan takes place during the rainy season (usually early June to mid July) when the prevailing wind is from the southwest. The airborne insects generally land on the side of hills away from the wind or in a protected valley facing windward. Survey of the planthopper population in Tsubo early in the season will aid in the assessment of planthopper abundance in any given year.

Stratigraphical sections along transects Z306–Z311 and Z313 on the west side of Rabbit Hill and Z305 on the north side of West Island in West Embayment (see Part 1, figure 2 for locations)

Stratigraphical sections along transects Z306–Z311 and Z313 on the west side of Rabbit Hill and Z305 on the north side of West Island in West Embayment (see Part 1, figure 2 for locations)

Stratigraphical sections along transect Z33 across the mouth of East Embayment and transects Z6–Z12 and Z101 on the south side of Rabbit Hill in the main basin (see Part 1, figure 2 for locations)

Stratigraphical sections along transect Z33 across the mouth of East Embayment and transects Z6–Z12 and Z101 on the south side of Rabbit Hill in the main basin (see Part 1, figure 2 for locations)

Dynamic electron transfers in B2H6 and Cu(PH3)2(BH4)

In order to investigate the coupling of molecular vibrations and electron distribution, dynamic electron transfers in B2H6 and Cu(PH3)2(BH4) are lated by using a new variational method. In both molecules, the dynamic electron density near bridging hydrogen atoms decreases to form the density valley by exciting specific vibrational modes. On the other hand, in both sides of the valley density hills grow up. For these molecules, similar contour maps are given by the modes with different symmetry which have large contribution of the bridging ligands. While the dynamic electron transfer of B2H6 arises in symmetric form, the vibrational modes of the Cu complex gives the asymmetric redistribution of the dynamic electron density. This is attributed to the difference of the symmetry between the two molecules.

Effect on the introduction of 4 wheel drive tractor in hill side area

Effect on the introduction of 4 wheel drive tractor in hill side area

Survey of damages during the Dhamar earthquake of 13 December 1982 in the Yemen Arab Republic

Abstract The Dhamar province of the Yemen Arab Republic was shaken on 13 December 1982 by a moderate earthquake. The earthquake caused considerable loss of life and different degrees of damage to the traditional houses in the area. The most common forms of construction, consisting of stone masonry and adobe, suffered very extensive damage. The destruction of houses was mainly due to failure of the superstructure and none due to the movement of foundations. An above-ground reinforced concrete water tank also collapsed. Ground fissures, rupture of stones on a hill side, rock falls, and slides were also observed. An isoseismal map of the earthquake-damaged area is also presented.

Taro Irrigation: A Descriptive Account from Wamira, Papua New Guinea

All gardeners know that their plants must have water or they die. But sometimes the sun shines too hot and fierce, and the clouds won't do their work and send down the rain. Then the gardener has to sit and see his plants wither, and he knows that his [taro tubers] will be small ones: and by and by he will go hungry . . . But long ages ago some gardeners made a discovery. They saw their gardens dry and dying, and they thought, 'Why wait for the rain which doesn't come? Why not bring the water onto our gardens by our own work? So they turned aside the streams that flowed on the hill sides; and they led the water by channels or 'races' down to their gardens on the flat (Papuan Villager 1929:6).

The Far Side of the Hill

The Far Side of the Hill

The bracken problem in the Highlands and Islands

SynopsisThe only serious attempt to quantify the area of bracken in Scotland took place in 1957. At that time the Department of Agriculture for Scotland, through the medium of the June Agricultural Census, asked farmers to assess the area of bracken on each holding.The survey produced a figure of 187,500 ha of bracken-infested land throughout Scotland, of which some 50% was found in the Central, North and West Highland counties of Perth, Inverness and Argyll. One quarter (46,875 ha) of the Scottish total was located on the mainland and islands of Argyll.Distribution is governed to a great extent by the soil type, exposure and rainfall, with the free-draining slopes of brown soil on the lower hill faces and glen sides providing the ideal habitat for the plant. The poorly drained acid peat as found over much of the Highland areas is an unsuitable medium for bracken growth but thin peat overlying mineral soil may be subject to bracken encroachment.The crux of the problem lies in the imbalance of brown soils to peat land.The limited areas of the mineral soils, which are located on the accessible lower slopes, have a marked potential for improved grazing and, by virtue of better drainage, are capable of more complete utilisation in an intensive stocking system.Bracken control and subsequent grass sward establishment can form the key to greatly increased levels of productivity. This is illustrated by detailed reference to one farm in Argyll where over the past five years an attempt has been made to operate the Hill Farming Research Organization (H.F.R.O.) concept of a Two Pasture System.