An efficient flamelet progress-variable method for modeling non-premixed flames in weak electric fields

Combustion stabilization and enhancement of the flammability limits are mandatory objectives to improve nowadays combustion chambers. At this purpose, the use of an electric field in the flame region provides a solution which is, at the same time, easy to implement and effective to modify the flame structure. The present work describes an efficient flamelet progress-variable approach developed to model the fluid dynamics of flames immersed in an electric field. The main feature of this model is that it can use complex ionization mechanisms without increasing the computational cost of the simulation. The model is based on the assumption that the combustion process is not directly influenced by the electric field and has been tested using two chemi-ionization mechanisms of different complexity in order to examine its behavior with and without the presence of heavy anions in the mixture. Using a one- and two-dimensional numerical test cases, the present approach has been able to reproduce all the major aspects encountered when a flame is subject to an imposed electric field and the main effects of the different chemical mechanisms. Moreover, the proposed model is shown to produce a large reduction in the computational cost, being able to shorten the time needed to perform a simulation up to 40 times.Comment: 26 pages, 13 figures, paper accepted for publication on Computers and Fluid

A Conjugate-heat-transfer Immersed-boundary Method for Turbine Cooling

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A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

In this paper we show and discuss the use of a versatile interaction potential approach coupled with an immersed boundary method to simulate a variety of flows involving deformable bodies. In particular, we focus on two kinds of problems, namely (i) deformation of liquid-liquid interfaces and (ii) flow in the left ventricle of the heart with either a mechanical or a natural valve. Both examples have in common the two-way interaction of the flow with a deformable interface or a membrane. The interaction potential approach (de Tullio & Pascazio, Jou. Comp. Phys., 2016; Tanaka, Wada and Nakamura, Computational Biomechanics, 2016) with minor modifications can be used to capture the deformation dynamics in both classes of problems. We show that the approach can be used to replicate the deformation dynamics of liquid-liquid interfaces through the use of ad-hoc elastic constants. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as deforming drop in a shear flow or a cross flow. We show that the same potential approach can also be used to study the flow in the left ventricle of the heart. The flow imposed into the ventricle interacts dynamically with the mitral valve (mechanical or natural) and the ventricle which are simulated using the same model. Results from these simulations are compared with ad- hoc in-house experimental measurements. Finally, a parallelisation scheme is presented, as parallelisation is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies on hundreds of distributed memory computing processors

Correlação entre produção e componentes do leite em gado de corte.

Este experimento teve como objetivo avaliar a produção e a composição do leite de vacas das raças Canchim e Nelore, tendo em vista o manejo da fase de cria de bovinos de corte

Relação do peso a desmama de bezerros da Raça Canchim e cruzados canchim x Nelore com constituintes do leite.

O trabalho teve como objetivo avaliar a importância das produções totais de proteÍnas, gordura e extrato seco total no leite, em 34 semanas de bezerros da raca Canchim e cruzados 1/2 Canchim + 1/2 Nelore.Resumo

Comportamento de pastejo de vacas das raças Canchim e Nelore.

Avaliação do tempo de pastejo de vacas das raças Canchim e Nelore paridas de agosto a outubro de 1989, amamentando bezerros canchins e 1/2 Camchi + 1/2 Nelore, respectivamente.Resumo

Associação entre características da amamentação e peso de bezerros da raça Canchim e cruzados Canchim X Nelore.

Avaliação da relação do numero de mamadas diárias (NM), duração da mamada (DM), e tempo total diário de amamentação (TT) com o peso de bezerros canchim (14) e 1/2 Canchim + 1/2 Nelore (13) e com produção de leite das vacas Canchim e Nelore

Dynamics of the aortic root functional unit using Direct Numerical Simulation

The dynamics of the functional unit aortic valve/aortic root/coronary arteries/ascending aorta is very complex owing to the interaction of several mechanisms that interfere each other; this makes in vivo and in vitro analyses very expensive and numerical simulations a desirable option. In this paper we describe an integrated tool that has been developed over the last decade capable of performing high-fidelity simulations which include the fluid/structure interaction, the deformability of the aortic wall and several other relevant features of the problem. Some representative results are described in order to show the capabilities of the method