Three-dimensional compressible turbulent computations for a diffusing S-duct

The purpose of the present study was to evaluate the capability of the computational fluid dynamics computer program PARC3D to model flow in a typical diffusing subsonic S-duct, with strong secondary flows. This evaluation is needed to provide confidence in the analysis of aircraft inlets, which have similar geometries. The performance predictions include total pressure profiles, static pressures, velocity profiles, boundary layer data, and skin friction data. Flow in the S-duct is subsonic, and the boundary layers are assumed to be turbulent. The results for both H and O grid solutions, are compared with existing test data

Three-dimensional compressible turbulent computations for a nondiffusing S-duct

The PARC3D code was used to compute the compressible turbulent flow within a three dimensional, nondiffusing S-duct. A frame of reference is provided for future computational fluid dynamics studies of internal flows with strong secondary flows and provides an understanding of the performance characteristics of a typical S-duct with attached flow. The predicted results, obtained with both H- and O-grids, are compared with the experimental wall pressure, static and total pressure fields, and velocity vectors. Additionally, computed boundary layer thickness, velocity profiles in wall coordinates, and skin friction values are presented

Einfluss von Mischanbau mit Hafer, flacher Bodenbearbeitung und Biofumigationsbrassicaceen auf Beikrautbesatz, Erbsenkrankheiten und Erträge in der Fruchtfolge mit Winterweizen

Experiments were conducted to determine how tillage intensity, the use of biofumigation brassica cover crops and mixed cropping with oats affect the performance of organic peas with respect to weed pressure, diseases, and yield. Fields were either ploughed to a depth of about 15-20 cm or only to about 8 cm in late summer followed by either Sinapis alba (low glucosinolate (GSC) content), Raphanus sativus (medium GSC) or Brassica juncea (high GSC). Brassicas were mulched in fall right before flowering and incorporated in the top soil. In mixtures with oats seed rate for peas was as in pure stands, for oats it was 20 %. There was a dramatic spring drought in 2011 resulting in severe water stress for the peas in 2011. Weeds were significantly reduced by about 45 % by oats in both years. Neither tillage nor any of the brassica cover crops or mixing with oats had a significant effect on root disease severity of peas or the pathogen composition. In both years pea lower stems and roots were mostly infected by Phoma medicaginis. In 2011, about half of the infected plants were also infected by Mycosphaerella pinodes and up to 20 % with Ascochyta pisi. Pea yields were 2.2 t ha-1 and 2.1 t ha-1 in 2010 and 2011, respectively. Oat yields were 3.0 and 4.9 t ha-1, respectively. Mixing with oats reduced pea yields by 32 and 63 % in 2010 and 2011, respectively while the oats yielded about 45 % of the pure stands. Tillage did not affect yields, however, pea yields in plots that had been planted to R. sativus as cover crop were significantly reduced. Subsequent wheat yields in the rotation were significantly higher after peas and the pea-oat mixture than after oats alone

Effekte von Kompostapplikationen auf Fußkrankheiten und Grünmasseertrag von Wintererbsen

Abstract: Effects of compost applications on foot diseases and biomass yield of winter peas. A field experiment was conducted to assess the effects of compost applications on the growth and health of winter peas from September 2009 to May 2010. A total of 5 t DM ha-1 of a 12 month old yard waste compost were applied in plots that were either uninoculated or inoculated with Phoma medicaginis grown on infested oat kernels. The control treatment received no compost and was left uninocu-lated. Main plots received all four treatments and were replicated four times. Compost slightly reduced the incidence of Mycosphaerella pinodes and Phoma medicaginis in March and the foot disease severity in May. Overall fresh matter production was significantly reduced by inoculation. These reductions were compensated by compost applications. There was great variation among main plots in the performance of the peas. Where peas performed poorly in the controls (i.e. low fresh matter yield) com-posts improved the performance considerably. Where performance was high, there were no more additional benefits of adding compost to the system