Windward Edge Research Articles

On the influence of windward edge structure and stand density on the flow characteristics at forest edges

Experimental investigations in an atmospheric boundary layer wind tunnel were carried out in order to study both the influence of the windward edge structure and the stand density on the flow characteristics near the canopy top of forest edges. For the edge structure investigation, two different types of forest edges were used. The taper angle was varied three times for both edge types, and all tapered edges were combined with both dense and sparse forest stands. In addition, a configuration was investigated where the airflow in the trunk space of the dense forest was blocked completely by an impermeable wall. In order to study the influence of stand density, forest stands were varied three times by removing whole rows of the originally dense model forest. The measurements show that a forest edge induces strong disturbances in the flow field at the near-edge region leading to an increased momentum transfer and to an increased wind loading on trees. The region of significant disturbances extends to a distance of about eight tree heights. Both edge density and taper angle determine the amount of volume influx through the edge, which seems to be primarily responsible for the flow field properties near the canopy top. It was found that for sparse forest stands, sloping tapered edges reduce the wind velocities nearest to the canopy. It could also be shown that the positive skewness of the near-canopy longitudinal velocity distribution is diminished with decreasing taper angle indicating that higher wind velocity fluctuations are reduced.

A comprehensive two-moment warm microphysical bulk scheme. II: 2D experiments with a non-hydrostatic model

A new bulk microphysical scheme containing advanced parametrizations to predict both concentration and mixing ratio of cloud droplets and raindrops (see Part I) is implemented in a three-dimensional non-hydrostatic model. This paper presents results obtained with the complete scheme for two specific experiments of idealized precipitating clouds. In the first case, an orographic cloud is produced at the windward edge of a plateau. The study focuses on the sensitivity of the microphysical fields and precipitation patterns to the upwind cloud condensation nuclei (CCN) activation spectrum. In the second case, a heavily precipitating tropical rainband of the Hawaiian Rainband Project is simulated in a kinematic framework. Analysis of simulated radar-reflectivity time evolution indicates that a realistic development of large raindrops can be obtained as compared to either observations or to results produced by a bin-resolving model. The overall control of raindrop tail distribution by collisional break-up is re-emphasized in the light of earlier results. The rather simple tests lead to the conclusion that a complete bulk microphysical scheme can simulate warm rain processes with reasonable accuracy. The ability of the model to account for realistic CCN activation spectra with modest programming effort makes the scheme suitable for three-dimensional precipitation simulations that properly take into consideration aerosol dynamics at mesoscale.

Large-eddy simulation of the flow around a freight wagon subjected to a crosswind

The purpose of the research reported in this paper is to investigate the aerodynamic response of a freight train subjected to a crosswind at 90° yaw angle using large-eddy simulation (LES). The freight train under investigation consists of many identical wagons. The wagons of the train are of the single-stacked container type that is having a box-like shape. In order to reduce the computational cost, attention is confined to the aerodynamic loads and flow structures around a selected single wagon from the middle of the train. The influences of the neighbouring wagons are simulated by imposing spanwise periodicity. The Reynolds number of the flow, based on the time-averaged speed of the crosswind and the height of the wagon from the ground, is 300,000. The standard Smagorinsky model with model constant of 0.1 and the Van Driest damping function, implemented in the commercial CFD package CFX, are used. The assessment of LES accuracy was carried out by performing three different computations using three different meshes; coarse, medium and fine. The fine mesh simulation gives results similar to that of the medium mesh simulation. The LES results showed that the flow moves in the gaps between the containers and under the wagon with high speed resulting in a much more complex flow topology in the wake of the wagon compared to that previously published around passenger trains. The flow separates at the sharp windward edge of the container to form a large separated flow region on the roof of the container. Aerodynamic forces on the container and freight wagon were computed and their time history was used to reveal the characteristic frequencies of the flow motion around the body. Further, the effect of the moving ground on aerodynamic coefficients is investigated by performing simulation on a moving ground. As a result of the floor motion, the side force coefficient was reduced by about 2.5% while the lift force was increased by about 11%.

Wind Conditions in Idealized Building Clusters: Macroscopic Simulations Using a Porous Turbulence Model

Simulating turbulent flows in a city of many thousands of buildings using general high-resolution microscopic simulations requires a grid number that is beyond present computer resources. We thus regard a city as porous media and divide the whole hybrid domain into a porous city region and a clear fluid region, which are represented by a macroscopic k–\({\varepsilon}\) model. Some microscopic information is neglected by the volume-averaging technique in the porous city to reduce the calculation load. A single domain approach is used to account for the interface conditions. We investigated the turbulent airflow through aligned cube arrays (with 7, 14 or 21 rows). The building height H, the street width W, and the building width B are the same (0.15 m), and the fraction of the volume occupied by fluid (i.e. the porosity) is 0.75; the approaching flow is parallel to the main streets. There are both microscopic and macroscopic simulations, with microscopic simulations being well validated by experimental data. We analysed microscopic wind conditions and the ventilation capacity in such cube arrays, and then calculated macroscopic time-averaged properties to provide a comparison for macroscopic simulations. We found that the macroscopic k–\({\varepsilon}\) turbulence model predicted the macroscopic flow reduction through porous cube clusters relatively well, but under-predicted the macroscopic turbulent kinetic energy (TKE) near the windward edge of the porous region. For a sufficiently long porous cube array, macroscopic flow quantities maintain constant conditions in a fully developed region.

Fog Water and Ecosystem Function: Heterogeneity in a California Redwood Forest

Fog is thought to influence ecological function in coastal forests worldwide, yet few data are available that illuminate the mechanisms underlying this influence. In a California redwood forest we measured water and nitrogen (N) fluxes from horizontally moving fog and vertically delivered rain as well as redwood tree function. The spatial heterogeneity of water and N fluxes, water availability, tree water use, and canopy N processing varied greatly across seasons. Water and N fluxes to soil (annual average of 98% and 89%, respectively) across the whole forest occurred primarily in the rain season and was relatively even across the whole forest. In contrast, below-canopy flux of fog water and N declined exponentially from the windward edge to the forest interior. Following large fog events, soil moisture was greater at the windward edge than anywhere else in the forest. Physiological activity in redwoods reflected these differences in inputs across seasons: tree physiological responses did not vary spatially in the rain season, but in the fog season, water use was greater, yet water stress was less, in trees at the windward edge of the forest versus the interior. In both seasons, vertical passage through the forest changed the amount of water and form and concentration of N, revealing the role of the tree canopy in processing atmospheric inputs. Although total fog water inputs were comparatively small, they may have important ecosystem functions, including relief of canopy water stress and, where there is fog drip, functional coupling of above- and belowground processes.

Form–flow interactions of an aeolian saucer blowout

AbstractAirflow patterns through a saucer blowout are examined from wind speed and direction measurements made during a chinook wind event. The blowout long‐axis is oriented east–west with a broad depositional apron on the east side. Wind directions during the event rotated from south‐westerly to westerly, permitting an assessment of oblique and axis‐parallel flows. Results show that airflow passing over the windward rim of the saucer blowout expands and decelerates, leading to flow separation and a small re‐circulation zone on sheltered lee slopes. Near the deflation basin, airflow re‐attaches to the blowout surface and accelerates up to a small opening in the east rim, where it can be up to 50% faster than on the windward edge. Beyond the downwind rim the airflow expands and decelerates and sand is deposited onto a broad apron. Similar to coastal trough blowouts, the degree of airflow steering and acceleration along the deflation basin is determined by the angle of incidence between the approach wind and the long‐axis of the blowout. As the angle of incidence increases wind speed accelerates at 0·3 m above the surface of the deflation basin and the degree of airflow steering increases. Overall, a two‐fold process is identified, where south‐westerly flows have greater potential for eroding the deflation basin, while westerly flows have greater potential for evacuating sand from within the blowout. Visual observations indicate that sand eroded from the deflation basin during south‐westerly flows is re‐distributed to adjacent zones of low wind speed until axis‐parallel winds evacuate the sand through the opening in the east rim. Morphometric changes since 1994 indicate that the blowout morphology has remained relatively constant, suggesting a persistent interplay between oblique and axis‐parallel wind erosion events. Collectively, these findings indicate that the angle of approach winds is an important control on saucer blowout morphodynamics. Copyright © 2009 John Wiley & Sons, Ltd.

Biological soil crust distribution is related to patterns of fragmentation and landuse in a dryland agricultural landscape of southern Australia

The dryland agricultural landscape of north-west Victoria, Australia, includes isolated remnants of eucalypt woodland that are exposed to ongoing disturbance from sheep grazing and cropping activity. Biological soil crusts are a functionally important feature of these woodland communities. We used a modern form of regression (boosted regression tree (BRT) models) to investigate relationships between crust abundance and environmental and landscape variables. We also investigated whether the use of broad morphological groups of crust organisms is more informative than simply measuring total crust cover. Remnant size was the single most influential variable for crust abundance, with negligible crust cover in small patches (<5 ha). The BRT model also identified relationships between crust abundance and available P, soil C and perennial grass. We argue that disturbance from stock grazing and camping is the mechanism driving these relationships. Other variables related to crust abundance were proximity to the windward edge, litter cover and tree cover. Morphological groups showed a differential response to some variables, suggesting assessment of total cover may mask important patterns in community structure. Crust disturbance represents a serious issue for maintenance of ecosystem function in the study region, particularly loss of crusts from small remnants because the majority of remnants are small.

Blowing in the wind? Nutrient enrichment of remnant woodlands in an agricultural landscape

Increasing fertiliser use in agricultural landscapes is likely to threaten the viability of remnant native vegetation in many parts of the world. Australia’s prime grain production landscapes have nutrient poor soils, which formerly supported semi-arid woodland. The ecological function and capacity for regeneration of these remnants may be particularly susceptible to nutrient enrichment. The key sources of nutrients are wind and water deposition from crop fertilisation, and manure and feed from sheep. We hypothesised that these sources would result in unequal deposition of nutrients within and among remnant vegetation patches. We surveyed soil nutrients (Total N, Available P and K, C:N ratio, and soil pH) in the edges and interiors of 60 remnant woodland patches of various sizes, and in adjacent cultivated paddocks. Nutrient load was negatively correlated with remnant size and patterns were particularly strong for available P. Small remnant patches (<3 ha) were accumulation zones for nutrients, with levels comparable or higher than within crop lands. The patterns are consistent with the hypothesis that small remnants are strongly enriched as a result of being used for livestock shelter. In larger remnants, the primary cause of enrichment is consistent with edge accumulation of nutrients due to wind and water movement. In large patches, remnant edges, particularly the windward edge, were elevated compared to interiors of large patches. In these semi-arid crop lands, current trends in intensification of cropping and a shift away from livestock may reduce the input of nutrients to small patches but increase the nutrient threat to larger remnants.

Stability of Rice Pollination in The Field Under Hot And Dry Conditions in The Riverina Region of New South Wales, Australia

Even Under Extremely Hot (40ºC) Conditions During Anthesis, Heat-induced Floret Sterility Does Not Appear To Be A Serious Issue For Australian Rice Growers. This Contradicts Previously Reported Temperature Thresholds For Floret Sterility. To Determine The Factors Associated With Stable Rice Production Under Hot and Dry Conditions in The Riverina Region of New South Wales (Australia), We Examined Rice (Cv. ‘Langi’) Pollination At Different Distances From The Windward Edge of A Paddy Field and Its Association With Canopy Microclimate. With An Air Temperature of 34.5ºC and A Relative Humidity of 20.7% During Anthesis, Poor Pollination of Florets Occurred At The Windward Edge, But Pollination Remained Stable Farther From The Edge. The Temperature Difference Between The Air and The Panicles in The Canopy Reached As High As 6.8ºC Under These Conditions Because of Low Humidity and Strong Transpirational Cooling. Moreover, The Length of The Dehiscence At The Base of The Thecae During Anthesis Was Long; This Is A Desirable Trait For Heat Tolerance. The Long Basal Dehiscence of The Thecae of This Cultivar and The Lower Panicle Temperatures Relative To The Ambient Temperature Caused By High Transpirational Cooling Appear To Be The Key Factors Responsible For Stable Pollination Under The Extremely High Temperatures of The Riverina Region.

Rain Forest Islands in the Chilean Semiarid Region: Fog-dependency, Ecosystem Persistence and Tree Regeneration

Tree presence in semiarid ecosystems is generally constrained by insufficient annual rainfall. However, in semiarid Chile, rainforest patches dominated by Aextoxicon punctatum are unexpectedly found on coastal mountaintops (450–600 m) at 30°S, surrounded by a xerophytic vegetation matrix that receives only 147 mm of annual precipitation. It has been proposed that these forests persist as a result of fog-water inputs. If so, then because fog-water deposition is spatially heterogeneous and shows strong edge effects, the potential environmental gradient created by the direction of fog input should determine forest structure and tree regeneration patterns. To investigate this hypothesis, we measured fog inputs, forest structural attributes (age and size distribution, basal area, and coarse woody debris), and tree regeneration in three different habitats: the windward edges (WE), leeward edges (LE), and the interior (center) of rainforest patches varying in area from 0.2 to 22 ha. Mean fog-water input was estimated from passive collectors over 1 year in WE and LE of patches. Tree regeneration was greater in the WE and forest interior (FI) and decreased toward the LE of patches, following a marked pattern of decline in fog inputs. Older trees and coarse woody debris were concentrated in the FI and LE of patches. Tree regeneration and patch structure appear to be largely controlled by fog-input direction and edge effects. We propose that forest patches may be slowly growing toward the incoming fog edge, while dying at the opposite edge.

流れと風圧の同時測定による立方体屋根面上流れの時空間構造と風圧特性の評価

In order to clarify characteristics of temporal-spatial flow structures above and wind pressures on the roof of a cubic structure, a wind tunnel experiment was carried out in two types of turbulent boundary layers. The flow was measured by Particle Image Velocimetry (PIV) system and simultaneous multi-pressure measurements on the surface were also performed. The time-averaged separation bubble on the roof had flat shape with a gradual curvature. When the intensity of turbulence of the approaching flow was large, and strong local negative pressure was generated in the windward edge corner, a flat conical vortex was formed, and the spatial structure of the flow was different from the time-averaged flow.

Airflow Patterns through Roof Openings of a Naturally Ventilated Greenhouse and their Effect on Insect Penetration

Experiments were carried out to study the airflow through continuous vertical roof openings of a naturally ventilated greenhouse. The major objectives of this work were to investigate the effect of ambient wind speed and direction, with respect to the greenhouse, on the mean and turbulent characteristics of the airflow. The air velocity was measured simultaneously at the two edges of each of the greenhouse openings by one-dimensional sonic anemometers and at the mid-span of the openings by a three-dimensional sonic anemometer. It is shown that when the wind is not perpendicular to the plane of the openings there are outflow and inflow, at the windward and leeward edges of the openings, respectively. A wind blowing from the back of the openings and nearly perpendicular to them reduced the mean air velocity at the two edges but did not change the turbulent velocity much. Over a considerable part of the day the mean and turbulent air velocities scale with the ambient wind. Monitoring whitefly population in the roof openings and around the greenhouse indicated a main daily activity period between 08:00 and 12:00. The number of whiteflies trapped under the eastern roof opening was significantly higher than the number trapped under the other roof openings. This was in agreement with the higher probability to have inflow in the eastern opening than in the western one as measured by the sonic anemometers.

Heat Fluxes and Airflow Patterns Through Roof Windows in a Naturally Ventilated Enclosure

Experiments were carried out to study the airflow and heat transfer through continuous vertical roof openings of a naturally ventilated greenhouse. The major goals of this work were to investigate the effect of ambient wind speed and direction with respect to the greenhouse on the mean and turbulent characteristics of the air velocity and heat transfer through openings with and without insect-proof screens. Air velocity and temperature were measured simultaneously at two edges of the opening using one-dimensional sonic anemometers and miniature thermocouples. It is shown that when the wind is not perpendicular to the plane of the openings there are outflow and inflow, at the windward and leeward edges of the openings respectively. A wind blowing from the back of the openings and nearly perpendicular to them reduced the mean air velocity at the two edges but did not change the turbulent velocity much. Over a considerable part of the day the mean and turbulent air velocities scale with the ambient wind; the total heat flux (mean plus turbulent) scales with the product of the ambient wind and temperature while the turbulent heat flux does not. The integral length scale of the inflow was approximately equal to the height of the opening and was larger than that of the outflow. Installing screens on the openings generated smaller scales and increased the spectral decay rate in comparison with openings without screens. A quadrant analysis enabled the determination of the events that significantly contribute to the turbulent heat flux. It is shown that at the outflow the turbulent heat flux is mainly due to eddies of cool air entering from the surrounding to the greenhouse while at the inflow it is due to both warm and cool eddies leaving and entering the greenhouse respectively.

強風下における機械的固定工法による防水層の挙動の風洞実験による観察

A waterproofing membrane is partially fixed to a substrate by fasteners in mechanically anchored systems. For designing a safer anchored waterproofing system against typhoons, it is needed to make clear the behavior of it under strong wind. Two kinds of full size specimens with a parapet and without one were exposed to high wind speed of a wind tunnel. The behavior of the system was investigated from the three aspects such as wind forces to a membrane, deformation of a membrane and tensile forces of fasteners induced by high wind. Strong wind force was observed in the area close to the windward edge for the roof without a parapet and about 1m on the leeward from a parapet for the roof with a parapet. The membrane was lifted up by wind to about 60mm in maximum height and was extended to about 0.6% in maximum elongation and it oscillated about 5-20Hz in periodic time. The tensile force of more than 160N was observed in some fasteners, depending on the location in the roof.

Vulnerability to wind damage in managed landscapes of the coastal Pacific Northwest

Managed forested landscapes in the coastal Pacific Northwest follow a pattern of transition from dominance by naturally regenerated second growth to dominance by planted stands. This transition should have dramatic influence on many characteristics of these landscapes and the larger region, including susceptibility to wind damage. In this paper, inventory and spatial information from an example landscape are integrated using the Landscape Management System to produce alternative management scenarios and evaluate the projections using a wind damage vulnerability rating system. Planted Douglas-fir stands tend to develop higher height to diameter ratios in the dominant trees, are thinned more often, and tend to have more exposed windward edges; characteristics which increase susceptibility to wind damage. In this analysis, the increasing vulnerability factors are mostly compensated for by the reduced rotation lengths expected in the plantations. The pattern of transition in managed landscapes generates an associated pattern of vulnerability to wind damage. Homogeneously and heterogeneously aged landscapes have distinct patterns of vulnerability. These differences could be harnessed to enhance the particular goals associated with managing individual ownerships.

Changes in soil properties after afforestation in Horqin Sandy Land, North China

We studied the changes in soil properties after afforestation on desertification-affected sandy soils to estimate how much time would be required for soils to recover enough for use in sustainable food production. We surveyed soils near and within 3-, 9-, and 19year- old plantations of poplar (Poplus simonii) in the central part of Naiman County, eastern Inner Mongolia, China. Changes in the soil properties following afforestation included an accumulation of fine particles (clay + silt) and soil organic carbon (SOC) in the surface horizons. The contents of fine particles and SOC increased slowly in the first 9-year period and then rapidly between 10 and 19 years, being higher at concave than convex sites. Soil parameters such as available moisture level, amounts of available N and available P, and CEC that control soil fertility showed a similar trend to that of the contents of fine particles and SOC. The contents of fine particles and SOC were higher at the windward edge than in the center of the 19-year-old poplar plantation, suggesting that the accumulation of fine particles was caused by the decrease in wind velocity due to the presence of vegetation. The increase in the SOC content may be caused by the increased carbon input to soils from the vegetation and by the deposition of fine particles with a higher C concentration than that of native sandy soils. Soil fertility, represented by the amounts of available N in the upper 20 cm layer of the soil, recovered after 19 years under poplars, and was similar to that of adjacent fertile cropland. However, the amount of available N under plantations younger than 10 years was lower than that in cropland soils, suggesting that a period of between 10 and 20 years is required for soils to recover from desertified conditions and be utilized for intensive crop farming once again.

The impact of trampling on feldmark vegetation in Kosciuszko National Park, New South Wales

A popular walking track in Kosciuszko National Park, New South Wales, passes through areas of feldmark vegetation, a windswept community of sparse dwarf shrubs, cushion plants and herbs. The prevailing westerly winds in this area prune the windward edges of the dominant Epacris gunnii shrubs. Layering on the protected side effectively means that the shrubs slowly move across the ridgetops. Twenty-five transects were placed perpendicular to the track in a patch of feldmark north of Mt Kosciuszko. The density of selected species and the total number of species were recorded in quadrats placed in the track centre, track edges and feldmark vegetation at 5 and 10 m from both sides of the track to determine whether the track has interrupted feldmark processes and affected species abundance. The abundance of all species and the number of species per quadrat was lowest in the track centre. Three species (including E. gunnii) were found to be less abundant on the leeward edge of the track than on the windward edge, suggesting that the track has indirectly interfered with feldmark processes. Two of the species were as abundant on track edges as at 5 and 10 m from the track. The area of affected vegetation is currently very small and it may take decades before the effect is obvious to people using the track. Management options for reducing or eliminating the impact are discussed.

Effects of routine late-season field operations on numbers of boll weevils (Coleoptera: Curculionidae) captured in large-capacity pheromone traps.

Flat and cylindrical adhesive boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), pheromone traps captured significantly more (P < or = 0.05) boll weevils than the Hercon (Hercon Environmental, Emigsville, PA) trap during the late cotton-growing season, and larger adhesive areas were associated with higher captures; a flat plywood board collected the most boll weevils because it had the largest surface area. The flat board trap, chosen for measuring large late-season adult boll weevil populations common to the Lower Rio Grande Valley of Texas in 2000 and 2001, collected more (P < or = 0.05) weevils when deployed in proximity to natural and cultivated perennial vegetation, and mean numbers of captured boll weevils were higher (P < or = 0.0001) on the leeward sides of the board traps than on the windward sides. The board trap had an estimated potential capacity of approximately 27,800 boll weevils, and the large capacity of the board trap allowed for more accurate measurements of large adult boll weevil populations than the more limited Hercon trap. Measurement of adult boll weevil numbers after the routine field operations of defoliation, harvest, shredding, and stalk-pulling, demonstrated that large populations of boll weevils persist in cotton fields even after the cotton crop has been destroyed. Increases (P < or = 0.05) in the percentage variation of trapped boll weevils relative to the numbers collected just before each field operation were observed after defoliation, harvest, shredding, and stalk-pulling, but the percentage variations followed a quadratic pattern with significant correlation (P < 0.0001; 0.59 < adjusted r2 < 0.73). Numbers of adult boll weevils caught on board traps deployed at 15.24-m intervals on windward and leeward edges of cotton fields suggested that boll weevil populations in flight after field disturbances might be affected by large-capacity trapping.

Unsteady flow on the sides of a 6 m cube

Four ultrasonic anemometers have been used to measure flow velocities at two groups of positions at mid-height on a 6 m cube. One other ultrasonic anemometer, located upstream at cube height, provided reference wind data. The results obtained provide a picture of the mean and fluctuating parts of the flow. Mean velocity results indicate that with the wind perpendicular to one face, the flow detaches at the windward edge but is reattached to the sides by about x/ h=0.83. However, probability analysis shows that the velocity at this point is reversed for 54% of the time. In addition it is shown that while some of the fluctuations can be attributed to a quasi-steady response to variations in wind direction, the influence of building-induced turbulence is also very apparent. These results illustrate the highly turbulent and unsteady nature of flow on the sides of the cube.

A 6 m cube in an atmospheric boundary layer flow -Part 2. Computational solutions

Computation solutions for the flow around a cube, which were generated as part of the Computational Wind Engineering 2000 Conference Competition, are compared with full-scale measurements. The three solutions shown all use the RANS approach to predict mean flow fields. The major differences appear to be related to the use of the standard <TEX>$k-{\varepsilon}$</TEX>, the MMK <TEX>$k-{\varepsilon}$</TEX> and the RNG <TEX>$k-{\varepsilon}$</TEX> turbulence models. The inlet conditions chosen by the three modellers illustrate one of the dilemmas faced in computational wind engineering. While all modeller matched the inlet velocity profile to the full-scale profile, only one of the modellers chose to match the full-scale turbulence data. This approach led to a boundary layer that was not in equilibrium. The approach taken by the other modeller was to specify lower inlet turbulent kinetic energy level, which are more consistent with the turbulence models chosen and lead to a homogeneous boundary layer. For the <TEX>$0^{\circ}$</TEX> case, wind normal to one face of the cube, it is shown that the RNG solution is closest to the full-scale data. This result appears to be associated with the RNG solution showing the correct flow separation and reattachment on the roof. The other solutions show either excessive separation (MMK) or no separation at all (K-E). For the <TEX>$45^{\circ}$</TEX> case the three solutions are fairly similar. None of them correctly predicting the high suctions along the windward edges of the roof. In general the velocity components are more accurately predicted than the pressures. However in all cases the turbulence levels are poorly matched, with all of the solutions failing to match the high turbulence levels measured around the edges of separated flows. Although all of the computational solutions have deficiencies, the variability of results is shown to be similar to that which has been obtained with a similar comparative wind tunnel study. This suggests that the computational solutions are only slightly less reliable than the wind tunnel.