LES of recirculation and vortex breakdown in swirling flames

In this study large eddy simulation (LES) technique has been applied to predict a selected swirling flame from the Sydney swirl burner experiments. The selected flame is known as the SM1 flame operated with fuel CH4 at a swirl number of 0.5. In the numerical method used, the governing equations for continuity, momentum and mixture fraction are solved on a structured Cartesian grid. Smagorinsky eddy viscosity model with the localised dynamic procedure of Piomelli and Liu is used as the subgrid scale turbulence model. The conserved scalar mixture fraction based thermo-chemical variables are described using the steady laminar flamelet model. The GRI 2.11 is used as the chemical mechanism. The Favre filtered scalars are obtained from the presumed beta probability density function (beta-PDF) approach. The results show that with appropriate inflow and outflow boundary conditions LES successfully predicts the upstream recirculation zone generated by the bluff body and the downstream vortex breakdown zone induced by swirl with a high level of accuracy. Detailed comparison of LES results with experimental measurements show that the mean velocity field and their rms fluctuations are predicted very well. The predictions for the mean mixture fraction, subgrid variance and temperature are also reasonably successful at most axial locations. The study demonstrates that LES together with the laminar flamelet model in general provides a good technique for predicting the structure of turbulent swirling flames

Seletividade de acaricidas e inseticidas a ácaros predadores (Acari: Phytoseiidae) encontrados em seringueira no centro-oeste do Brasil Side-effect of acaricides and insecticides to predatory mites (Acari: Phytoseiidae) found in rubber-trees in mid-west Brazil

Euseius concordis (Chant) e Neoseiulus anonymus (Chant & Baker) são ácaros predadores da família Phytoseiidae comumente encontrados em seringueira (Hevea brasiliensis Muell. Arg.) em Mato Grosso, região centro-oeste do Brasil. Este trabalho foi realizado para verificar o efeito de acaricidas e inseticidas-acaricidas empregados em plantações de seringueira, e outros que teriam potencial para serem empregados contra insetos e ácaros considerados pragas dessa cultura, sobre E. concordis e N. anonymus. Utilizou-se o método residual de pulverização em superfície, recomendado como padrão pelo Grupo de Trabalho "Pesticidas e Artrópodes Benéficos", da Organização Internacional de Controle Biológico e Integrado de Plantas e Animais Nocivos/Seção Regional do Paleártico Oeste. Duas concentrações de cada um dos seguintes ingredientes ativos foram utilizadas: acefato, dicofol, endosulfan, formetanate, metomil, monocrotofós, óxido de fenbutatin e propargite. Uma das concentrações utilizadas foi uma média daquelas sugeridas pelos fabricantes para o controle de ácaros e insetos fitófagos presentes em outras culturas, uma vez que nenhum dos produtos testados tem registro para o uso em seringueira e a outra correspondeu à cerca de um terço da primeira. Endosulfan a 320ppm, dicofol a 100ppm e óxido de fenbutatin a 100 e 320ppm foram inócuos a E. concordis, enquanto que endosulfan a 320ppm e dicofol a 100ppm foram inócuos a N. anonymus. Acefato, formetanate e monocrotofós, nas concentrações testadas, foram nocivos às duas espécies.<br>Euseius concordis (Chant) and Neoseiulus anonymus (Chant & Baker) are predatory mites of the family Phytoseiidae commonly found on rubber trees (Hevea brasiliensis Muell. Arg.) in the State of Mato Grosso, in the mid-west Brazil. This work was conducted to verify the effect of acaricides and insecticides-acaricides occasionally used in rubber tree plantations, and other products that could be used against different pests (insects and mites) in this crop, on E. concordis and N. anonymus. The residual contact spray method in glass surface was used, which is recommended by the Working Group on "Pesticides and Benefic Arthropods" of the International Organization of Biologic and Integrated Control of Noxious Plants and Animals/Regional Section of the West Paleartic (IOBC/WPRS). Two concentrations of the following active ingredients were used: acephato, dicofofol, endosulfan, formetanate, metomil, monocrotophos, oxid of fenbutanin and propargit. For each product, one of the concentrations used was an average of the concentrations recommended by the manufacturers for the control of mites and phytophagous insects in other crops, since none of the tested products are registered for use on rubber tree. The other concentration corresponded to ca. a third of the former concentration. Endosulfan at 320ppm, dicofol at 100ppm and fenbutanin oxid at 100 and 320ppm were harmless to E. concordis, while endosulfan at 320ppm and dicofol at 100ppm were harmless to N. anonymus. Acephate, formetanate and monocrotofós, in concentrations, were harmful to both species

The Near-Earth Object Surveyor Mission

The Near-Earth Object (NEO) Surveyor mission is a NASA Observatory designed to discover and characterize asteroids and comets. The mission’s primary objective is to find the majority of objects large enough to cause severe regional impact damage (>140 m in effective spherical diameter) within its 5 yr baseline survey. Operating at the Sun-Earth L1 Lagrange point, the mission will survey to within 45° of the Sun in an effort to find objects in the most Earth-like orbits. The survey cadence is optimized to provide observational arcs long enough to distinguish near-Earth objects from more distant small bodies that cannot pose an impact hazard reliably. Over the course of its survey, NEO Surveyor will discover ∼200,000-300,000 new NEOs down to sizes as small as ∼10 m and thousands of comets, significantly improving our understanding of the probability of an Earth impact over the next century. © 2023. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]