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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Estudos de métodos numéricos para a simulação de escoamentos viscoelásticos com superfície livre / Numerical methods for viscoelastic free surface flows

Figueiredo, Rafael Alves 29 August 2011 (has links)
Neste projeto, é apresentado um método numérico com uma abordagem do tipoMAC para a simulação de escoamentos viscoelásticos incompressíveis tridimensionais com superfície livre governados pelo modelo de fluido SXPP. A formulação apresentada nesse trabalho é uma extensão dos resultados obtidos por Oishi et al. (2011), sobre o estudo de métodos numéricos para a simulação de escoamentos incompressíveis viscoelásticos com superfície livre a baixos números de Reynolds, para o caso bidimensional. No contexto de problemas transientes, metodologias explícitas para solução numérica das equações governantes apresentam restrições de estabilidade muito severas para a definição do passo temporal, acarretando em um custo computacional relativamente alto. Sendo assim, utilizamos um método implícito para resolver a equação de conservação da quantidade de movimento, eliminando assim, a restrição de estabilidade parabólica e diminuindo significativamente o custo computacional. Mas tal estratégia acopla os campos de velocidade e pressão. Dessa forma, para desacoplar esses campos, foi utilizado uma abordagem que combina método de projeção com uma técnica implícita para o tratamento da pressão na superfície livre. A equação constitutiva foi resolvida pelo método de Runge-Kutta de segunda-ordem. A validação do método numérico foi realizada utilizando refinamento da malha no escoamento em um canal. Como aplicação, apresentamos resultados numéricos sobre o problema do jato oscilante e do inchamento do extrudado / In this work, we present a numerical method with a MAC type approach to simulate tridimensional incompressible viscoelastic free surface flows governed by a SXPP (Single eXtended Pom-Pom) model. The formulation presented in this work is an extension to the work of Oishi et al. (2011). They have studied numerical methods for solving incompressible viscoelastic free surface flows with low Reynolds number, for the bidimensional case. In the context of transient problems, explicitmethodologies for the numerical solution of the governing equations present severe stability constraints for defining the time step, what highly increases the computational cost. Due to this fact, an implicit method is used to solve the momentum equation, eliminating the parabolic stability constraint and decreasing significantly the computational cost. However, this strategy couples velocity and pressure fields. To decouples this fields, it was used an approach that combines a projection method and an implicit technique for the treatment of the pressure at the free surface. The constitutive equation is solved by a second-order Runge-Kutta method. The numerical method validation was achieved by a mesh refinement for a flow in a channel. As applications, numerical results of the die-swell problem and the jet buckling phenomenon are presented
112

Finite difference and finite volume methods for wave-based modelling of room acoustics

Hamilton, Brian January 2016 (has links)
Wave-based models of sound propagation can be used to predict and synthesize sounds as they would be heard naturally in room acoustic environments. The numerical simulation of such models with traditional time-stepping grid-based methods can be an expensive process, due to the sheer size of listening environments (e.g., auditoriums and concert halls) and due to the temporal resolution required by audio rates that resolve frequencies up to the limit of human hearing. Finite difference methods comprise a simple starting point for such simulations, but they are known to suffer from approximation errors that may necessitate expensive grid refinements in order to achieve sufficient levels of accuracy. As such, a significant amount of research has gone into designing finite difference methods that are highly accurate while remaining computationally efficient. The problem of designing and using accurate finite difference schemes is compounded by the fact that room acoustics models require complex boundary conditions to model frequency-dependent wall impedances over non-trivial geometries. The implementation of such boundary conditions in a numerically stable manner has been a challenge for some time. Stable boundary conditions for finite difference room acoustics simulations have been formulated in the past, but generally they have only been useful in modelling trivial geometries (e.g., idealised shoebox halls). Finite volume methods have recently been shown to be a viable solution to the problem of complex boundary conditions over non-trivial geometries, and they also allow for the use of energy methods for numerical stability analyses. Finite volume methods lend themselves naturally to fully unstructured grids and they can simplify to the types of grids typically used in finite difference methods. This allows for room acoustics simulation models that balance the simplicity of finite difference methods for wave propagation in air with the detail of finite volume methods for the modelling of complex boundaries. This thesis is an exploration of these two distinct, yet related, approaches to wave-based room acoustic simulations. The overarching theme in this investigation is the balance between accuracy, computational efficiency, and numerical stability. Higher-order and optimised schemes in two and three spatial dimensions are derived and compared, towards the goal of finding accurate and efficient finite difference schemes. Numerical stability is analysed using frequency-domain analyses, as well as energy techniques whenever possible, allowing for stable and frequency-dependent boundary conditions appropriate for room acoustics modelling. Along the way, the use of non-Cartesian grids is investigated, geometric relationships between certain finite difference and finite volume schemes are explored, and some problems associated to staircasing effects at boundaries are considered. Also, models of sound absorption in air are incorporated into these numerical schemes, using physical parameters that are appropriate for room acoustic scenarios.
113

Solução numérica do modelo PTT para escoamentos viscoelásticos com superfícies livres / Numerical solution of the PTT model for viscoelastic surface flows

Paulo, Gilcilene Sanchez de 15 September 2006 (has links)
O objetivo deste trabalho é desenvolver um método numérico capaz de simular escoamentos viscoelásticos com superfícies livres governados pela equação constitutiva não-linear PTT (Phan-Thien-Tanner). Neste trabalho foram apresentados três métodos numéricos para simular escoamentos viscoelásticos modelados pela equação PTT. Dois desses métodos foram desenvolvidos para simular escoamentos viscoelásticos bidimensionais enquanto o terceiro método foi desenvolvido para simular escoamentos viscoelásticos tridimensionais. Estes métodos numéricos foram incorporados aos ambientes de simulação FreeDow2D e FreeDow3D, extendendo estes ambientes para escoamentos viscoelásticos descritos por uma equação constitutiva não-linear. Inicialmente, uma descrição de FreeDow2D e FreeDow3D é apresentada. As equações governantes para escoamentos descritos pelo modelo PTT são dadas na forma de tensorial e as formulações matemáticas para obtenção dos métodos numéricos são apresentadas. As equações que descrevem os métodos numéricos são resolvidas pela técnica de diferenças finitas numa malha deslocada e o fluido é representado por partículas arcadoras usando o método Marker-and-Cell. As condições de contorno para cada tipo de contorno são descritas em detalhes e o cálculo do tensor extra-tensão no contorno rígido é obtido utilizando as idéias de Tomé et al. [84] para o modelo Oldroyd-B. Seguindo a metodologia de Alves et al. [2], a solução analítica do modelo PTT para escoamentos totalmente desenvolvidos em um canal bidimensional é apresentada em detalhes. Esta solução analítica é então usada para validar o método numérico desenvolvido neste trabalho. Os métodos numéricos desenvolvidos nesse trabalho foram aplicados para simular os seguintes problemas: um jato de fluido viscoelástico incidindo numa placa rígida; o inchamento do extrudado e o problema de uma gota esférica de fluido viscoelástico incidindo perpendicularmente contra uma superfície rígida plana / The aim of this work is to develop a numerical method capable of simulating viscoelastic free surface flows governed by the non-linear constitutive equation PTT (Phan-Thien-Tanner). In this work three numerical methods to simulate vicoelastic Flows of fluids modelled by the PTT equation are presented. Two of these methods were developed to simulate two-dimensional viscoelastic flows while the third method was developed to simulate three-dimensional viscoelastic flows. These numerical methods were incorporated into the codes FreeFlow2D and FreeFlow3D, extending these codes to viscoelastic flows described by the non-linear constitutive equation PTT. Initially, a description of FreeFlow2D and FreeFlow3D is presented. The governing equations for flows described by the PTT model are given in index form and the mathematical formulations for obtaining the numerical methods are presented. The equations describing the numerical methods are solved by the finite difference method on a staggered grid and the fluid is modelled using a Marker-and-Cell type method. The boundary conditions for each type of boundary are described in details and the calculation of the extra-stress tensor on rigid boundaries is performed using the ideas of Tomé et al. [84] for an Oldroyd-B Fluid. Following the methodology presented by Alves et al. [2], the analytic solution of the PTT model for fully developed flows in a two-dimensional channel is presented in details. This analytic solution is then used to validate the numerical method developed in this work. Finally, the numerical methods developed in this work were applied to simulate viscoelastic flows such as a viscoelastic jet flowing onto a rigid plate, the extrudate swell of viscoelastic fluids and the simulation of a viscoelastic drop hitting a rigid plate
114

Modelagem bidimensional do movimento da água em condições de solo não saturado / Two-dimensional modeling of water movement in unsaturated soils

Arraes, Francisco Dirceu Duarte 28 August 2014 (has links)
O conhecimento da distribuição da umidade no solo para diferentes tipos de solos e diferentes vazões pode ser aplicado na otimização do dimensionamento de um sistema de irrigação, no manejo da água na zona radicular, bem como, auxiliar na aplicação eficiente de fertilizantes na rizosfera. Portanto, objetivou-se com a presente pesquisa desenvolver um modelo numérico bidimensional capaz de simular a distribuição da umidade no perfil de solo para diferentes sistemas de irrigação. Sendo que para tal, o modelo utiliza o método das diferenças finitas, mediante uma discretização da solução da equação de Richards e o método iterativo de Picard, o qual foi utilizado para garantir a conservação da massa. O modelo numérico ainda torna possível considerar a extração de água pelas plantas e a evaporação da água na superfície do solo. E para avaliar o seu desempenho foi feita uma análise de sensibilidade. O modelo matemático foi desenvolvido no Departamento de Engenharia de Biossistemas, pertencente à Escola Superior de Agricultura \"Luiz de Queiroz\" - ESALQ/USP. A linguagem de programação utilizada foi Fortran 90. A estrutura computacional foi feita de forma a permitir ao usuário a entrada de informações tais como: a) dados do perfil do solo, no que se refere às suas propriedades físico-hídricas, b) informações sobre o tipo de irrigação, tempo de simulação, tempo de aplicação de água via irrigação. O programa permite ao usuário a opção entre simular a extração de água pela as plantas ou não. Para a validação do modelo foram utilizados os dados obtidos por Rivera (2004), em um experimento conduzindo no antigo Departamento de Engenharia Rural da Escola Superior de Agricultura \"Luiz de Queiroz\". O desempenho do modelo foi avaliado com base nos parâmetros estatísticos: índice de concordância de Willmott; coeficiente de eficiência, raiz quadrada do erro médio, erro médio e o erro máximo absoluto. A análise de sensibilidade do modelo foi avaliada em função dos parâmetros: densidade de fluxo de água, condutividade hidráulica do solo saturado, alfa e n (parâmetros de ajuste da curva de retenção). Pelos resultados obtidos, o modelo apresentou um desempenho satisfatório na simulação dos perfis de umidade em relação aos dados medidos em condições de experimento em solo não saturado. Em relação à análise de sensibilidade, o modelo apresentou maior sensibilidade aos parâmetros de fluxo de entrada e ao parâmetro n da equação de retenção, indicando que tais parâmetros de entrada, necessitam ser determinados com maior precisão. Houve baixa sensibilidade ao parâmetro \"alfa\" da curva de retenção. / The soil moisture distribution for different soil types under different flow regimes can be used to optimize the design of an irrigation system, water manage water in the root zone, or increase the precision of the application of fertilizers in the rhizosphere. Therefore, the objective of this research was to develop a two-dimensional numerical model capable of simulating the soil moisture distribution in soil profile for different irrigation systems. The model is a finite difference solution of the Richards equation solution, in which the Picard iteration method is used to ensure the conservation of mass. The numerical model also takes water extraction by plants and water evaporation on the soil surface into account. The mathematical model was developed in the Department of Biosystems Engineering, College of Agriculture \"Luiz de Queiroz\", ESALQ / USP. It was coded in Fortran 90, and structured to allow interactive input of a) physical and hydraulic properties soil profile, and b) type of irrigation, irrigation application time, and simulation. The simulation of water extraction by the plants is optional. And to evaluate its performance a sensitivity analysis was done. Data obtained in an experiment carried out in the older Rural Engineering Department, College of Agriculture \"Luiz de Queiroz\" by Rivera (2004), were used to validate the model. Model performance was evaluated using the Willmott index of agreement; efficiency coefficient, root mean square error, average error and the maximum absolute error. Sensitivity analyses were performed on the density of water flow, saturated hydraulic conductivity, and on alpha and n (setting parameters of the soil water retention curve). From the results obtained, the model satisfactory simulated the measured soil moisture distributions in the experimental soil moisture profiles. The model was most sensitive to variations in the parameters of the input stream and to n, a parameter in the soil water retention equation (van Genuchten model, 1980). This results is indicative that these input parameters need to be determined with greater accuracy. The model output was not very sensitive to alpha, a shape parameter in the soil water retention curve.
115

Analysis and design of planar active and passive quasi-optical components using new FDTD techniques

Vazquez, Javier January 2002 (has links)
New Quasi-optical sensor technology, based on the millimetre and submillimetre band of the electromagnetic spectrum, is actually being implemented for many commercial and scientific applications such as remote sensing, astronomy, collision avoidance radar, etc. These novel devices make use of integrated active and passive structures usually as planar arrays. The electromagnetic design and computer simulation of these new structures requires novel numerical techniques. The Finite Difference Time Domain method (FDTD) is well suited for the electromagnetic analysis of integrated devices using active non-linear elements, but is difficult to use for large and/or periodic structures. A rigorous revision of this popular numerical technique is performed in order to permit FDTD to model practical quasi-optical devices. The system impulse response or discrete Green's function (DGF) for FDTD is determined as a polynomial then the FDTD technique is reformulated as a convolution sum. This new alternative algorithm avoids Absorbing Boundary Conditions (ABC's) and can save large amounts of memory to model wire or slot structures. Many applications for the DGF can be foreseen, going beyond quasi-optical components. As an example, the exact ABC based on the DGF for FDTD is implemented for a single grid wall is presented. The problem of time domain analysis of planar periodic structures modelling only one periodic cell is also investigated. Simple Periodic Boundary Conditions (PBC) can be implemented for FDTD, but they can not handle periodic devices (such as phased shift arrays or dichroic screens) which produce fields periodic in a 4D basis (three spatial dimensions plus time). An extended FDTD scheme is presented which uses Lorentz type coordinate transformations to reduce the problem to 3D. The analysis of non-linear devices using FDTD is also considered in the thesis. In this case, the non linear devices are always model using an equivalent lumped element circuit. These circuits are introduced into the FDTD grid by means of the current density following an iterative implicit algorithm. As a demonstration of the technique a quasi-optically feed slot ring mixer with integral lens is designed for operation at 650 GHz.
116

FDTD modelling of nanostructures at microwave frequency

Turati, Paolo January 2014 (has links)
The thesis which is hereby presented describes a study of the numerical modelling of the coupled interaction of nanostructures with electromagnetic fields in the range of microwaves. This is a very ambitious task and requires a thorough and rigorous implementation of new algorithms designed to this purpose. The first issue to be encountered is the characterisation and the physical understanding of the behaviour of a nanostructure. The term itself, nanostructure, defines any device which has a nanometric size in at least one dimension, regardless of its material and geometry, hence it is a very wide definition. Carbon Nanotubes (CNT), quantum dots and quantum wells fall into this category, for example, and in electronics these structures are generally composed of semiconductor materials, like Silicon or Gallium Arsenide. The first step to take, in order to model such objects from an electronics point of view, is to solve the Schrodinger equation. The Schrodinger equation is a very general formula, widely used in quantum physics, which, when provided with a certain electrical potential in a material, determines the behaviour of the electrons in this material. Needless to say, the electrical potential is the DNA of a material or, in other words, it is the physical property which affects the propagation of electrons and therefore makes a material conducting or non-conducting. Nanostructures are often composed of several materials, hence the potential is not constant and, with opportune geometries, it is possible, in principle, to guide the electron currents through the device, as, for example, a channel in a MOSFET. This principle holds for very small structures where the electron transport can be considered ballistic, i.e. when the structures are smaller than the free mean path of the particle. The behaviour of the electrons is affected both by external factors, such as temperature or applied electric and magnetic fields, and internal factors, such as the electron mobility or the doping concentration, which are dependent on the used materials. This parameters play a very important role whilst modelling the behaviour of particles such as electrons and in this work the main focus is the study of the impact of external electromagnetic fields. The electromagnetic fields (EM fields) are composed of an electric field component and of a magnetic field component, which can be analysed separately in order to better understand the response of nanostructures to their application. A rigorous analysis is presented by showing numerical results, obtained with the modelling of the Schrodinger equation, compared with the expected theoretical results, exploiting simple structures, where it is possible to calculate the solutions analytically. The second part of thesis focuses on the impact of the EM fields on the nanostructure, hence the combined effect of both electric and magnetic fields affecting the electrons' propagation, and the mutual coupling of the fields with the quantum effects. Indeed the study of nanodevices for microwave applications requires to consider the contribution of a parameter called quantum current density, which accounts for the quantum effects generated by the structure. This is normally ignored in conventional devices because the quantum contributions are negligible but, by using opportune materials and opportune geometries, these currents become relevant and they may have an impact on the propagation of the EM fields. For this reason a consistent part of the thesis is dedicated to investigate the mutual coupling between EM fields and quantum effects, by implementing the Maxwell-Schrodinger coupled model. A chapter is dedicated to the novel approaches taken in order to tackle the issues and the limits of the numerical implementation; in particular two solutions are presented, nonuniform domains and the parallelisation of the algorithm. These approaches are vital whilst modelling numerically such physical problems since the required computational capacity increases with the accuracy requirements. Solving the presented algorithms conventionally would limit the potential of the method and thus a thorough study has been made in order to improve the efficiency of the simulations. In the last chapter, three different scenarios are presented, each one of them showing different features of the coupled model. The results are illustrated and discussed, including the limits due to the chosen approximations. References to the analytical solutions are provided in order to validate the obtained numerical results.
117

Implementation of Some Finite Difference Methods for the Pricing of Derivatives using C++ Programming.

Ampadu, Ebenezer 18 May 2007 (has links)
In this project,European Call and Put options,and also American Call and Put options have been priced by some finite difference methods using the C++ programming language.The report describes the following:The theory behind the pricing of options,some pricing methods,and how some finite difference pricing methods have been implemented in C++.
118

On the Performance of In-Body RF Localization Techniques

Swar, Pranay P 01 June 2012 (has links)
"Localization inside the human body using Radio Frequency (RF) transmission is gaining importance in a number of applications such as Wireless Capsule Endoscopy. The accuracy of RF localization depends on the technology adopted for this purpose. The two most common RF localization technologies use Received Signal Strength (RSS) and Time-Of-Arrival (TOA). This research first provides bounds for accuracy of localization of a Endoscopy capsule inside the human body as it moves through the gastro-Intestinal track with and without randomness in transmit power using RSS based localization with a triangulation algorithm. It is observed that in spite of presence of a large number of anchor nodes; the localization error is still in range of few cm, which is quite high; hence we resort to TOA based localization. Due to lack of a widely accepted model for TOA based localization inside human body we use a computational technique for simulation inside and around the human body, named Finite Difference Time Domain (FDTD). We first show that our proprietary FDTD simulation software shows acceptable results when compared with real empirical measurements using a vector network analyzer. We then show that, the FDTD method, which has been used extensively in all kinds of electromagnetic modeling due to its versatility and simplicity, suffers seriously because of its demanding requirement on memory storage and computation time, which is due to its inherently recursive nature and the need for absorbing boundary conditions. In this research we suggest a novel computationally efficient technique for simulation using FDTD by considering FDTD as a Linear Time Invariant (LTI) system. Then we use the software to simulate the TOA of the narrowband and wideband signals propagated inside the human body for RF localization to compare the accuracies of the two using this method. "
119

Simulação numérica da fase líquida na deposição de filmes finos via sol-gel: aplicações para dióxido de estanho

Sano, Dayene Miralha de Carvalho [UNESP] 18 March 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-18Bitstream added on 2014-06-13T21:02:05Z : No. of bitstreams: 1 sano_dmc_dr_bauru.pdf: 2390435 bytes, checksum: c70bb14dca9d8503f9a9ce373ebe90a2 (MD5) / Neste trabalho foi realizada a simulação numérica da fase líquida no processo de deposição de filmes finos pela técnica de molhamento (dip-coating), via sol-gel, utilizando como aplicação soluções precursoras de dióxido de estanho (Sn'IND. 2'). Dióxido de estanho é um semicondutor transparente de gap largo, amplamente utilizado em muitos tipos de dispositivos. Além da técnica convencional, o trabalho analisa uma nova proposta da técnica de deposição dip-coating onde a solução se encontra em uma temperatura diferente da ambiente. Para ambas as técnicas foram realizadas a modelagem matemática dos problemas e desenvolveu-se um método numérico apropriado baseado no método MAC (Marker and Cell). O problema foi resolvido em coordenadas cartesianas bidimensionais e as equações foram discretizadas pela técnica de diferenças finitas. Os resultados numéricos são visualizados por meio da distribuição de temperatura e vetores velocidade da solução precursora, que fornecem subsídios para investigação da influência dos vetores velocidade na obtenção de filmes com boas propriedades, em relação à uniformidade e homogeneidade. Verifica-se que estas características refletem diretamente na qualidade óptica dos filmes investigados, tornando-se parâmetros importantes para aplicações em dispositivos opto-eletrônicos. Através dos resultados numéricos verificou-se que nas regiões do fluido próximas ao substrato, os módulos dos vetores velocidade são maiores, há uma maior quantidade de material sendo depositado. Notou-se também, através da distribuição de velocidades em direção ao substrato que o filme tem uma melhor uniformidade na sua espessura quando os vetores velocidade possuem os valores de seus módulos mais próximos uns dos outros. Portanto, mudando os parâmetros iniciais de viscosidade, densidade, velocidade de imersão/emersão do substrato ou temperatura no fluido pode-se estudar o comportamento. / In this work, the numerical simulation of liquid phase in the thin film deposition, by the sol-gel-dip-coating technique, was carried out. The method was applied to tin dioxide (Sn'IND. 2') solutions. Tin dioxide is a transparent semiconductor of wide bandgap, extensively used in many types of devices. Besides the conventional procedure, this work analyses a new proposal for the deposition technique, where the solution is heated above room temperature. In both cases, the mathematical modeling was done and the appropriated numerical method was developed, based on MAC (Marker and Cell) approach. The problem was solved in two-dimensional Cartesian coordinates and the equations were discretized by the finite difference technique. The numerical results are visualized through temperature and vector velocity distributions in the precursos solution, yielding subsides to the investigation of the influence of vectors velocity in the deposition of good property films, concerning uniformity and homogeneity. It was verified that these characteristics point directly toward the optical quality of investigated films, becoming important parameters for application in optoelectronic devices. The numerical results allow verifying that in the fluid regions close to the substrate, where the velocity modulus is highter, there is a larger amount of material being deposited. It was also noticed, through the velocity distribution towards the substrate, that the film has a better thickness uniformity when the vectors velocity have modulus values closer to each other. Therefore, changing initial parameters such as viscosity, density, substrate dipping rate or fluid temperature, it is possible to evaluate the fluid behavior during the thin film deposition.
120

Modelagem bidimensional do movimento da água em condições de solo não saturado / Two-dimensional modeling of water movement in unsaturated soils

Francisco Dirceu Duarte Arraes 28 August 2014 (has links)
O conhecimento da distribuição da umidade no solo para diferentes tipos de solos e diferentes vazões pode ser aplicado na otimização do dimensionamento de um sistema de irrigação, no manejo da água na zona radicular, bem como, auxiliar na aplicação eficiente de fertilizantes na rizosfera. Portanto, objetivou-se com a presente pesquisa desenvolver um modelo numérico bidimensional capaz de simular a distribuição da umidade no perfil de solo para diferentes sistemas de irrigação. Sendo que para tal, o modelo utiliza o método das diferenças finitas, mediante uma discretização da solução da equação de Richards e o método iterativo de Picard, o qual foi utilizado para garantir a conservação da massa. O modelo numérico ainda torna possível considerar a extração de água pelas plantas e a evaporação da água na superfície do solo. E para avaliar o seu desempenho foi feita uma análise de sensibilidade. O modelo matemático foi desenvolvido no Departamento de Engenharia de Biossistemas, pertencente à Escola Superior de Agricultura \"Luiz de Queiroz\" - ESALQ/USP. A linguagem de programação utilizada foi Fortran 90. A estrutura computacional foi feita de forma a permitir ao usuário a entrada de informações tais como: a) dados do perfil do solo, no que se refere às suas propriedades físico-hídricas, b) informações sobre o tipo de irrigação, tempo de simulação, tempo de aplicação de água via irrigação. O programa permite ao usuário a opção entre simular a extração de água pela as plantas ou não. Para a validação do modelo foram utilizados os dados obtidos por Rivera (2004), em um experimento conduzindo no antigo Departamento de Engenharia Rural da Escola Superior de Agricultura \"Luiz de Queiroz\". O desempenho do modelo foi avaliado com base nos parâmetros estatísticos: índice de concordância de Willmott; coeficiente de eficiência, raiz quadrada do erro médio, erro médio e o erro máximo absoluto. A análise de sensibilidade do modelo foi avaliada em função dos parâmetros: densidade de fluxo de água, condutividade hidráulica do solo saturado, alfa e n (parâmetros de ajuste da curva de retenção). Pelos resultados obtidos, o modelo apresentou um desempenho satisfatório na simulação dos perfis de umidade em relação aos dados medidos em condições de experimento em solo não saturado. Em relação à análise de sensibilidade, o modelo apresentou maior sensibilidade aos parâmetros de fluxo de entrada e ao parâmetro n da equação de retenção, indicando que tais parâmetros de entrada, necessitam ser determinados com maior precisão. Houve baixa sensibilidade ao parâmetro \"alfa\" da curva de retenção. / The soil moisture distribution for different soil types under different flow regimes can be used to optimize the design of an irrigation system, water manage water in the root zone, or increase the precision of the application of fertilizers in the rhizosphere. Therefore, the objective of this research was to develop a two-dimensional numerical model capable of simulating the soil moisture distribution in soil profile for different irrigation systems. The model is a finite difference solution of the Richards equation solution, in which the Picard iteration method is used to ensure the conservation of mass. The numerical model also takes water extraction by plants and water evaporation on the soil surface into account. The mathematical model was developed in the Department of Biosystems Engineering, College of Agriculture \"Luiz de Queiroz\", ESALQ / USP. It was coded in Fortran 90, and structured to allow interactive input of a) physical and hydraulic properties soil profile, and b) type of irrigation, irrigation application time, and simulation. The simulation of water extraction by the plants is optional. And to evaluate its performance a sensitivity analysis was done. Data obtained in an experiment carried out in the older Rural Engineering Department, College of Agriculture \"Luiz de Queiroz\" by Rivera (2004), were used to validate the model. Model performance was evaluated using the Willmott index of agreement; efficiency coefficient, root mean square error, average error and the maximum absolute error. Sensitivity analyses were performed on the density of water flow, saturated hydraulic conductivity, and on alpha and n (setting parameters of the soil water retention curve). From the results obtained, the model satisfactory simulated the measured soil moisture distributions in the experimental soil moisture profiles. The model was most sensitive to variations in the parameters of the input stream and to n, a parameter in the soil water retention equation (van Genuchten model, 1980). This results is indicative that these input parameters need to be determined with greater accuracy. The model output was not very sensitive to alpha, a shape parameter in the soil water retention curve.

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