ABSTRACT: Two-dimensional flows over harmonically oscillating symmetrical aerofoil at reduced frequency of 0.1 were investigated for a Reynolds number of 135,000, with focus on the unsteady aerodynamic forces, pressure and vortex dynamics at post-stall angles of attack. Numerical simulations using ANSYS® FLUENT CFD solver, validated by wind tunnel experiment, were performed to study the method of sliding mesh employed to control the wing oscillation. The transport of flow was solved using incompressible, unsteady Reynolds-Averaged Navier-Stokes equations. The 2-equation k-ε realizable turbulence model was used as turbulence closure. At large angle of attack, complex flows structure developed on the upper surface of the aerofoil induced vortex shedding from the activity of separated flows and interaction of the leading edge vortex with the trailing edge one. This interaction at some stage promotes the generation of lift force and delays the static stall. In this investigation, it was found that the sliding mesh method combined with the k-ε realizable turbulence model provides better aerodynamic loads predictions compared to the methods reported in literature.

Este estudo foi realizado para determinar aspectos morfológicos, fisiológicos e nutricionais (teor vitamínico) de 45 acessos de beldroegas coletadas em diferentes locais da Península Ocidental da Malásia. Observaram-se diferenças significativas (p<0,05) para todos os caracteres avaliados, considerando-se características morfológicas, fisiológicas e de composição. Para as características morfológicas observaram-se as seguintes variações: altura das plantas (20,06-40,8 cm); número de ramos principais (1,4-4,4); número de nós (8,4-31); distância entre internódio (2,1-3,43 cm); diâmetro do caule (2,12-3,8 mm); número de folhas (97-1.019); área foliar (1,03-2,21 cm²); número de flores (14-826,8); comprimento da raiz (5,09-11,7 cm); peso fresco (40-280 g); e massa seca (2,71-29,16 g). Dentre as características fisiológicas verificaram-se as seguintes variações: teor de clorofila total (26,2-39,52; valor SPAD); fotossíntese líquida (20,8-28,73 mol CO2/m²/s); condutância estomática (0,02-0,28 cm/s); taxa de transpiração (0,46-2,48 mol/m²/s); e déficit de vapor d'água (0,51-2,65 mol H2O/m²/s). As análises de macro e micronutrientes indicaram que todos os acessos apresentam quantidade significativa de nutrientes essenciais. Entre os macronutrientes: N, P, K, Ca e Mg variaram, respectivamente, entre 31,2-100; 2,51-8,2; 78,4-276; 9,1-62,2; e 8,7-32,55 ppm. Enquanto os micronutrientes; Zn, Fe e Mn variaram, respectivamente, entre 0,31-1,09; 1,01-13,09; e 0,06-1,32 ppm. Essa grande variabilidade entre os acessos de beldroegas pode contribuir para o melhoramento genético dessa espécie.

This study was carried out to determine, evaluation and characterization of the morphological, physiological as well as mineral nutrient vitiations among all forty five purslane accessions collected from different locations of West Peninsular, Malaysia. Significant differences (p<0.05) were observed for all those traits measured regarding morphological, physiological and mineral composition. Morphological traits viz. plant height varied between 20.06-40.8 cm; number of main branch, 1.4-4.4; number of nodes, 8.4-31; internode distance, 2.1-3.43 cm; stem diameter, 2.12-3.8 mm; number of leaves, 97-1019; leaf area, 1.03-2.21 cm², number of flowers, 14-826.8; root length, 5.09-11.7 cm; fresh weight, 40-280 g; and dry weight varied between 2.71-29.16 g. Among physiological traits, total chlorophyll content varied between 26.2-39.52 (SPAD value), net photosynthesis, 20.8-28.73 µmol CO2/m²/sec; stomatal conductance, 0.02-0.28 cm/sec; transpiration rate, 0.46-2.48 mol/m²/sec; and water vapor deficit varied between 0.51-2.65 mol H2O/m²/sec. Analysis of mineral macro and micro nutrient compositions showed that all accessions contained appreciable amount of essential nutrients. Among the macro nutrient elements; N, P, K, Ca and Mg contents ranged respectively between 31.2-100, 2.51-8.2, 78.4-276, 9.1-62.2 and 8.7-32.55 ppm. Whereas micro nutrient elements; Zn, Fe and Mn ranged respectively between 0.31-1.09; 1.01-13.09 and 0.06-1.32 ppm. This great variability among the purslane accessions may contribute enhancing the genetic improvement of the species for desired traits.

As análises de qualidade de Lençol de Água incluíram pH, EC, e os cations,(Ca2+, Mg2+, Na+, K+, Zn2+, Cu2+, Mn2+, Fe3+ e As3+), aníons ( CO32-, HCO3-, NO3-, SO42-, PO43- e Cl-e TDS do noroeste do Bangladesh. As amostras continham Ca2+, Mg2+ e Na+ e como o cations dominante HCO3- e Cl foram os aníons dominantes. Segundo o TDS e valores de SAR, todas as amostras foram classificadas como categorias 'de água doce' e 'excelentes'. O SSP de todas as águas foi nas classes 'excelentes' e 'boas'. Todas as amostras foram dentro da classe 'suave' quanto à dureza com RSC 'conveniente'. Baseado As3+, Zn2+, Mn2+, Fe3+, SO42-, NO3- e Cl- - todas as amostras de lençol de água foram dentro do limite 'seguro' como água de bebida mas impróprias para algumas indústrias que emprega íons específicos.

Groundwater quality analyses included pH, EC, cations (Ca2+, Mg2+, Na+, K+, Zn2+, Cu2+, Mn2+, Fe3+ and As3+), anions (CO32-, HCO3-, NO3-, SO42-, PO43- and Cl-) and TDS of northwestern Bangladesh. The samples contained Ca2+, Mg2+ and Na+ as the dominant cations and HCO3- and Cl- were the dominant anions. Ratios of major cations and anions of water samples suggest the predominance of Ca and Mg-containing minerals over Na-containing minerals. According to TDS and SAR values, all samples were classed as 'freshwater' and 'excellent' categories. The SSP of all waters was under 'excellent' and 'good' classes. All samples were within 'soft' class regarding hardness with 'suitable' RSC. Based on As3+, Zn2+, Mn2+, Fe3+, SO42-, NO3- and Cl- all groundwater samples were within the 'safe' limit for drinking but unsuitable for some industries for specific ions.