PRELIMINARY RESULTS OF LARGE EDDY SIMULATIONS OF A HYDROCYCLONE

Subgrid-scale modeling, which characterizes Large Eddy Simulation (LES), has been used to predict the behavior of a water-fed hydrocyclone operating without an air core. The governing equations were solved by a fractional step method on a staggered grid. The Smagorinsky subgrid-scale model was employed to account for turbulent effects. Numerical results actually capture the main features of the flow pattern and agree reasonably well with experiments, suggesting that LES represents an interesting alternative to classical turbulence models when applied to the numerical solution of fluid flows within hydrocyclones

ON THE FLOW PAST RECTANGULAR CYLINDERS: PHYSICAL ASPECTS AND NUMERICAL SIMULATION

This paper concerns with unsteady incompressible flows around rectangular cylinders with side ratio varying from 1 to 10. Phenomenological aspects are discussed and numerical simulations are performed using a SIMPLEC finite volume code. A third-order QUICK scheme is employed for the advective terms in the Navier-Stokes equations, while a second-order fully implicit method is used for the time discretization. For validation purpose, preliminary simulations are carried out at Re = 300. Afterwards, the flow patterns and the wake periodic features are examined at Re = 1,000, 5,000, and 22,000, for which turbulent effects should not be neglected. In some of those cases, large-eddy simulation (LES) is employed, using the classical sub-grid Smagorinsky model. Important physical mechanisms determining vortex shedding frequency are placed in evidence. The present predictions are compared with numerical and experimental results from other works and a good agreement is reached

A PENDULUM-BASED MODEL FOR FLUID STRUCTURE INTERACTION ANALYSES

In the present contribution a pendulum-based model is used to represent fluid-structure interactions. For this purpose, a theoretical and experimentalanalysis of the dynamic behavior of a viscously damped spherical non rotational single-degree-of-freedom pendulum was performed. The dampingprocess is characterized according to two different regimes: in the first, it can be seen as a viscous low Reynolds’ number flow and, in the second, it can be considered as a viscously damped system. The pendulum was tested experimentally in a large reservoir containing a Newtonian fluid for validation purposes and good agreement was found between numerical and experimental results

NUMERICAL ANALYSIS OF THE NATURAL CONVECTION IN HORIZONTAL ANNULI AT LOW AND MODERATE Ra

The natural convection at low and moderate Rayleigh numbers (Ra) incylindrical horizontal annuli with imposed temperatures in both surfaces isnumerically studied. This flow inside concentric cylinders classic configuration has a wide range of practical and technological applications, which justifies its growing studies efforts. In this work, the governing equations are discretized by the volume finite technique over a staggered grid, with second-order accuracy in space and time. The flow pattern is presented by several Rayleigh numbers, with an analysis of the heat transfer coefficient and flow properties. Furthermore, a three-dimensional field is shown at a moderate Ra number. The results showed a good agreement with the experimental data

Influência da densidade de cultivo de Brachiaria ruziziensis sobre a germinação de apotécios de Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum é o agente causal do mofo branco em mais de 400 espécies hospedeiras e sobrevive no solo por vários anos por meio de estruturas de resistência (escleródios), e que dificilmente são afetados por fungicidas ou por algumas práticas culturais. Estas estruturas tendem a se esgotar após sua germinação e, desta forma, este trabalho teve como objetivo de verificar o efeito da espécie não-hospedeira Brachiaria ruziziensis cultivada sob diferentes densidades na germinação carpogênica de escleródios. Fo

Metodologia de amostragem, separação e quantificação de escleródios de Sclerotinia sclerotiorum a partir de solo naturalmente infestado.

Este trabalho apresenta uma metodologia para obtenção de escleródios a partir de amostras de solo possibilitando estimar o número de escleródios presentes na área

Conservação in vitro de germoplasma de mandioca.

A mandioca é nativa do continente americano, cultivada atualmente em muitos países, sendo o sexto produto alimentar da humanidade em volume de produção. Diante da relevância dessa cultura, a conservação in vitro constitui-se numa ferramenta importante para auxiliar na preservação de seus recursos genéticos

Efeito da densidade de Brachiaria ruziziensis na germinação carpogênica de escleródios em área naturalmente infestada por Sclerotinia sclerotiorum.

Entre as dificuldades para o controle do mofo branco, está a sobrevivência de escleródios do patógeno Sclerotinia sclerotiorum no solo por vários anos, que dificilmente são afetados por fungicidas ou por várias práticas culturais. Estes escleródios, porém, podem ser mortos por esgotamento após germinação ou parasitismo. Em um experimento realizado em Jataí, GO, avaliou-se a germinação de escleródios e posterior produção de apotécios, em tratamentos sem cobertura do solo, e sob cultivo de Brachiaria ruziziensis estabelecida em março de 2008, com 150, 300, 450 ou 600 pontos de valor cultural (PVC)