Neste trabalho é proposta uma metodologia numérica como ferramenta para avaliação de ambientes térmicos com manequins. A simulação de CFD do ambiente térmico em simulador comercial é integrada à simulação do sistema térmico do corpo humano realizada em código acadêmico. As soluções dos fluxos de calor e temperaturas nas peles são retroalimentadas e a transferência de informações é realizada via arquivo. A geometria do ambiente térmico é simplificada para minimizar os efeitos de problemas com a malha computacional na simulação de CFD, permitindo uma melhor análise do método interativo proposto. O manequim é separado em 15 segmentos cilíndricos representando cabeça, pescoço, tronco, braços, antebraços, mãos, coxas, pernas e pés. Cada segmento é subdividido em quatro quadrantes, totalizando 60 zonas, para capturar assimetrias térmicas e aerodinâmicas. Foi conduzido estudo de validação geométrica de manequim virtual pela comparação de resultados dos coeficientes térmicos obtidos com CFD e resultados obtidos de ensaios experimentais da literatura. A qualidade da malha e o tratamento de parede são discutidos. Os resultados tornam evidente que uma geometria simplificada do manequim é suficiente para estudos e avaliações de ambiente térmico e de conforto térmico quando se utiliza técnicas numéricas de CFD. Os resultados a partir da integração dos simuladores mostram que o método numérico pode ser instável nos segmentos com baixo metabolismo e baixa vazão de sangue, como nos pés e mãos. Pretende-se introduzir na metodologia proposta algum mecanismo que identifique automaticamente este fenômeno, para evitar a divergência do método e tornar a ferramenta mais robusta. / In this work is proposed a new numerical methodology as a tool for thermal comfort evaluation. This method promotes the interaction of the thermal environment simulation and the thermal system of the human body simulation. The commercial CFD simulator FLUENT R and an academician code for human body simulation are used. The solutions are fed back and the transfer is made by file. The geometry of the room is simplified to minimize the effects of problems with the computational mesh in the CFD simulation, allowing a better analysis of the proposed interactive method. The dummy is separated into 15 cylindrical segments representing head, neck, trunk, arms, forearms, hands, thighs, legs and feet. Each segment is subdivided into four quadrants, totaling 60 zones, to capture asymmetries in the heat flux field and temperature field. Was conducted a geometric validation of virtual dummy by comparing results of heat transfer coefficients from literature and CFD simulation. The mesh quality and near wall treatment are discussed. The results show that a simplified geometry of the dummy is sufficient for thermal environment studies and evaluations in CFD simulations. The results from coupled simulations show that the numerical method can be unstable in the segments with low metabolism and low blood flow, as the feet and hands. So, its intended to introduce mechanisms in the methodology to automatically identify this phenomenon and to avoid the divergence of the method to make more robust this methodology.

[pt] O objetivo principal do presente trabalho foi investigar computacionalmente o escoamento e a dispersão de poluentes atmosféricos sobre topografias complexas tridimensionais em escala de laboratório. Foram realizadas simulações numéricas de escoamentos neutros e estavelmente estratificados sobre colinas e também sobre terreno plano. A modelagem matemática, baseada na solução das equações gerais de conservação, inclui o modelo de tensões de Reynolds para a turbulência e um modelo de duas camadas para o tratamento do escoamento na região próxima à parede. O código comercial Fluent (Versão 6.0.12), que emprega o método de volumes finitos, foi utilizado nas simulações computacionais. Os resultados numéricos foram comparados a dados obtidos em experimentos em túnel de vento disponíveis na literatura. Também foram realizadas comparações com resultados obtidos com a utilização do modelo (k menos épsilon) clássico. A comparação entre os resultados obtidos com as diversas modelagens numéricas e os dados experimentais mostrou que a utilização conjunta do modelo de tensões de Reynolds e do tratamento em duas camadas produziu os melhores resultados na predição do escoamento. O desempenho dessa modelagem foi particularmente superior na representação da recirculação no escoamento na região a jusante da colina. Com relação ao cálculo das concentrações, os resultados obtidos foram razoáveis nas regiões mais distantes da fonte quando comparados aos experimentais. Na região mais próxima à fonte emissora, foram calculadas concentrações excessivamente altas ao nível do solo. Estas discrepâncias foram atribuídas ao fato de ter-se utilizado um modelo de difusividade turbulenta isotrópica para os cálculos da dispersão turbulenta do poluente. Ainda assim, os campos de concentrações apresentados mostraram importantes aspectos qualitativos relativos ao problema como, por exemplo, os efeitos da estabilidade atmosférica na dispersão do poluente, que foram adequadamente previstos. / [en] The main objective of the present work was to investigate computationally the flow and the dispersion of atmospheric pollutants over three dimensional complex topographies in laboratory scale. The investigations included the numerical simulation on the neutral and stably stratified flows over hills and flat terrain. The mathematical model was based on the solution of the general conservation equations and included the Reynolds stress model for turbulence and a two layer zonal model for the flow treatment in the near wall region. The commercial code Fluent (Version 6.0.12), which is based on the finite volume method, was employed in the computational simulations. The numerical results were compared to data obtained in wind tunnel experiments, available in the literature. Comparisons were also made with results obtained by employing the standard (k less épsilon) model for turbulence. The comparisons between the experimental data and the numerical results showed that the combined use of the Reynolds stress model and the two layer treatment provided the best results for the flow representation. This modeling approach was particularly superior in representing the flow recirculation on the leeside of the hill. The predicted concentrations results were reasonably good at regions far away from the emission source. In the near source regions, the ground level concentrations were overestimated by the numerical modeling. These discrepancies were attributed to the employment of an isotropic turbulent diffusivity model in the turbulent dispersion calculations. Nevertheless, the calculated concentration fields represented well important qualitative features of PUC Rio.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2018. / A membrane distillation crystallization (MDC) experimental setup was designed, constructed and commissioned with rectangular mixing crystallizer tanks. The advantages and disadvantages of a rectangular mixing tank are compared to the traditional cylindrical mixing tank with baffling by means of a computational fluid dynamic (CFD) analysis in Ansys Fluent. The effect of tank configuration and geometry on the hydrodynamic and mixing characteristics for efficient momentum, solid suspension, heat and mass transfer were investigated. The hydrodynamic conditions in a crystallizer-mixing tank determine the quality of fluid mixing essential for optimal crystallization. Forty-five degree pitched blade turbines (PBT) were used to provide the agitation in the stainless steel rectangular jacketed tanks. Clear polycarbonate replicas of the rectangular tanks were manufactured to visually observe the mixing process in the tanks. Silica particles were used to represent the calcium carbonate crystals in the experiment. The data gathered from these experiments showed that the tanks should be operated between 600 to 750 rpm in the CFD simulations to simulate partial to complete suspension. In the numerical simulations a rectangular tank was compared to a cylindrical tank with baffling of the same volume. The partial differential equations solved in the numerical simulation were the conservation of mass (continuity), conservation of momentum and additional turbulence equations. In order to solve the turbulent fluid flow characteristics, the industry standard two-equation model, namely the K-epsilon model was used. This model was refined by the addition of the Wen-Yu drag model, the Simonin turbulent dissipation and the Simonin et al. turbulence interaction models. The RANS based RNG (k-ε), derived from the instantaneous Navier-Stokes equation was selected as the preferred model to analyse the hydrodynamic flow fields in the tanks. The 3D sliding mesh method was used to compute a time accurate solution. The Eulerian-granular multiphase model was used to predict the degree of solids suspension in the tanks. The efficiency of mixing within the tank was measured by the tank’s ability to keep the crystals in suspension and preventing any particle from settling at the bottom for more than 1-2 second(s). The mixing tanks were initially loaded with 5% v/v, which equates to a loaded height of approximately 10 mm. The simulations were done with the use of the volume fraction function to visually observe the cloud height and gauge the homogeneity and distribution of the particulates within the fluid flow fields. The results from the experimental setup were compared to the CFD simulations to qualify the use of CFD simulations for the comparison of the geometrically different tanks. Lastly, the findings from the CFD simulations were used to compare the tanks and determine if the rectangular tank built for the MDC experiment perform satisfactorily to replace a standard cylindrical tank with baffling for this application.

For aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis is based on Rapid Distortion Theory (RDT), which describes the linear evolution of turbulent eddies as they are stretched by a mean flow distortion. Providing that the gust does not distort the mean flow streamlines the solution for a mean flow with shear is found to be the same as the solution for a mean potential flow with the addition of a potential flow gust. By investigating the inflow distortion of small-scale turbulence for various simple flows and rotor inflows with weak shear, it is shown that RDT can be applied to incompressible shear flows to determine the flow distortion. It is also shown that RDT can be applied to more complex flows modeled by the Reynolds Averaged Navier Stokes (RANS) equations. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

Boundary layers are regions where turbulence develops easily. In the case where the flow occurs on a surface showing a certain degree of roughness, turbulence eddies will interact with the roughness elements and will produce an acoustic field. This thesis aims at predicting this type of noise with the help of the Computational Fluid Dynamics (CFD) simulation of a wall jet using the Reynolds Average Navier-Stokes (RANS) equations. A frequency spectrum is reconstructed using a representation of the turbulence with uncorrelated sheets of vorticity. Both aerodynamic and acoustic results are compared to experimental measurements of the flow. The CFD simulation of the flow returns consistent results but would benefit from a refinement of the grid. The surface pressure spectrum presents a slope in the high frequencies close to the experimental spectrum. The far field noise spectrum has a 5dB difference to the experiments. / by Jean-Baptiste Blanc. / Thesis (M.S.C.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

The objective of this thesis is to analyze the flow past an ocean current turbine using a finite volume Navier-Stokes CFD solver. A full 3-D RANS approach in a moving reference frame is used to model the flow. By employing periodic boundary conditions, one-third of the flow-field is analyzed and the output is replicated to other sectors. Following validation of the computation with an experimental study, the flow fields and particle paths for the case of uniform and sheared incoming flows past a generic turbine with various blade pitch angles are evaluated and analyzed. Flow field and wake expansion are visualized. Eddy viscosity effects and its dependence on flow field conditions are investigated. / by Zaqie Reza. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

A common technique to improve the performance of shell and tube heat exchangers (STHE) is by redirecting the flow in the shell side with a series of baffles. A key aspect in this technique is to understand the interaction of the fluid dynamics and heat transfer. Computational fluid dynamics simulations and experiments were performed to analysis the 3-dimensional flow and heat transfer on the shell side of an STHE with and without baffles. Although, it was found that there was a small difference in the average exit temperature between the two cases, the heat transfer coefficient was locally enhanced in the baffled case due to flow structures. The flow in the unbaffled case was highly streamed, while for the baffled case the flow was a highly complex flow with vortex structures formed by the tip of the baffles, the tubes, and the interaction of flow with the shell wall. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Studies of composite multihull structure under wave loads, extreme loads, and blast loads have been conducted using finite element and computational fluid dynamics (CPF) tools. A comprehensive finite element tool for structural analysis of composite multi-hull structures is developed. Two-way fluid structure interaction (FSI) is implemented by coupling finite element analysis (FEA) and CFD. FEA models have been developed using sandwich construction having composite face sheets and a foam core. Fluid domain was modeled using the CFD code, CFX and a wave motion was simulated based on Sea State 5... In addition to hydrodynamic loads, the simulation of composite ship under extreme loads is performed. Stress analysis was performed and dynamic response of the hull was determined in time domain. In the final analysis, an underwater explosion model was developed to study the composite hull resistance to blast load. / by Siyuan Ma. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

A sudden expansion combustor (SUE) is analyzed using computation fluid dynamics (CFD). CO emissions and NOx emissions are computed for various operating conditions of the SUE combustor using a can type and an annular type geometrical configurations. The goal of this thesis is to see if the SUE combustor is a viable alternative to conventional combustors which utilize swirlers. It is found that for the can type combustor the NOx emissions were quite low compared to other combustor types but the CO emissions were fairly high. The annular combustor shows better CO emissions compared to the can type, but the CO emissions are still high compared to other combustors. Emissions can be improved by providing better mixing in the primary combustion zone. The SUE combustor design needs to be further refined in order for it to be a viable alternative to conventional combustors with swirlers. / by Daniel Rodriguez. / Thesis (M.S.C.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

ABE, V.C. Determinação de parâmetros de operação de sistema de distribuição de ar frio pelo piso em ambientes de escritórios. 2007. 132 p. Dissertação (Mestrado) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Atualmente, um dos principais requisitos para que um ambiente de escritório atenda plenamente às necessidades de uso e ocupação é a flexibilidade, mas com conforto. O sistema de distribuição de ar frio pelo piso (Underfloor Air Distribution System - UFAD) está sendo utilizado nos edifícios de escritórios para garantir a flexibilização integrada do sistema com o mobiliário. Trata-se de um sistema que fornece ar frio proveniente de um plenum, através de difusores localizados nos painéis do piso elevado. Os difusores de ar podem ser ajustados, ou reposicionados pelos próprios usuários dos ambientes, possibilitando o controle das condições térmicas no entorno próximo, de acordo com suas preferências individuais. Embora o sistema de distribuição de ar pelo piso apresente diversas vantagens com relação ao sistema de distribuição de ar convencional, ainda há falta de informações objetivas e diretrizes de projeto padronizadas, havendo a necessidade de realização de mais pesquisas na área. A introdução da Dinâmica dos Fluidos Computacional (Computational Fluid Dynamics - CFD) apresentou uma alternativa para as pesquisas experimentais relacionadas ao estudo do escoamento do ar. Assim, para o desenvolvimento do presente estudo foram utilizados recursos de dinâmica dos fluidos computacional, com o uso do código FLUENT. O objetivo do presente trabalho é apresentar uma estratégia para a determinação dos parâmetros de operação de sistemas de distribuição de ar pelo piso aplicados a ambientes de escritórios. A estratégia baseiase no estabelecimento de inter-relações entre os principais parâmetros que definem o escoamento do ar em ambientes com o sistema de distribuição de ar pelo piso: a vazão de ar insuflado, a temperatura do ar insuflado e a diferença de pressão entre o plenum pressurizado e o interior do ambiente. O emprego da estratégia possibilita que o projetista identifique as diversas combinações entre os parâmetros de operação que resultem numa mesma condição desejada, permitindo assim a escolha da opção mais satisfatória. / ABE, V.C. Determination of operation parameters of rooms with underfloor air distribution system. 2007. 132 p. Dissertation (Master Course) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Nowadays, one of the main requirements of an office room to fully attend the use and occupation needs is the flexibility, but with comfort. The underfloor air distribution system is being used in the office buildings to guarantee the integrated flexibility of the system with the furniture layout. The system supplies cooled air to the room from a pressurized plenum, passing through air diffusers located in the raised floor panels. The air diffusers can be adjusted or relocated by the room users themselves, making possible the control of the thermal conditions in their surroundings, according to their individual preferences. Though the underfloor air distribution system presents a lot of advantages with regard to conventional overhead distribution systems, there is still a lack of objective information and standardized guidelines, and the necessity of accomplishment of more researches about the subject. The introduction of Computational Fluid Dynamics presented an alternative for the experimental tests related to the study of airflow in rooms. Thus, for the development of the present study a CFD tool was used, the code FLUENT. The purpose of the present work is to develop a strategy for the determination of the operation parameters of an underfloor air distribution system applied to office rooms. The strategy is based on the establishment of interrelations between the main parameters that define the airflow in rooms with the underfloor air distribution system: the input volume flux, the input air temperature and the pressure difference between underfloor plenum and the room. The use of this strategy enables the designer to identify several combinations of the operation parameters that result in one desired condition, allowing the choice of the most satisfactory option.