The evaluation of wastewater concentrations in coastal environments has to be accurate for water ... more The evaluation of wastewater concentrations in coastal environments has to be accurate for water quality control. The description of the physical process in a comprehensive model is a complex task. Due to the different spatial and temporal scales involved, the use of different numerical models is required: far-field hydrodynamic models; near-field and pollutant transport models. In this paper, a coupled application of these models is described. Capabilities and limitations of modelling techniques applied to wastewater mixing and dispersion from submerged multiport discharges are discussed for environmental impact analysis. The recommended procedure combines a near-field mixing zone model, such as NRFIELD, with the Lagrangian far-field flow and water quality models within SisBaHia ® (http://www.sisbahia.coppe.ufrj.br/). The results showed that the model coupling improves the description and analysis of treated wastewater discharges over large scales. This allows a more realistic evaluation of the environmental impact due to domestic sewage discharges in coastal waters.
A procedure for the optimisation of hydrokinetic turbine array layout through surrogate modelling... more A procedure for the optimisation of hydrokinetic turbine array layout through surrogate modelling is introduced. The method comprises design of experiments, computational fluid dynamics simulations, surrogate model construction, and constrained optimisation. Design of experiments are used to build polynomial and Radial Basis Function surrogates as functions of two design parameters: inter-turbine longitudinal and lateral spacing, with a view to approximating the capacity factor of turbine arrays with inline and staggered layouts, each of which having a fixed number of turbines. For this purpose, two scenarios have been used as case studies, considering uniform and non-uniform free-stream flows. The major advantage of this method in comparison to those reported in the literature is its capability to analyse different design parameter combinations that satisfy optimality criteria in reasonable computational time, while taking into account complex floweturbine interactions and different turbine types.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2014
ABSTRACT This paper presents a simple and effective method to model the wetting and drying of coa... more ABSTRACT This paper presents a simple and effective method to model the wetting and drying of coastal areas by the tide. The approach considers an equivalent "rough-porous layer" (RPL), wetting and drying method. The method can be easily implemented in finite elements, which makes it useful in numerical modeling of natural water bodies with intricate topographies. Some benchmark tests are devised to examine the performance and robustness of the method at extreme conditions, with satisfactory results. Finally, the effectiveness of the RPL is evaluated in modeling the complex Vitória Bay in Brazil, with its extensive mangrove areas, where the predicted variations in the inundation areas and the velocity fields were reproduced more accurately for different stages of the tide. At field measurement sites, the predicted water levels and velocities agreed favorably with the measured data.
ABSTRACT This paper presents a simple and effective method to model wetting and drying processes ... more ABSTRACT This paper presents a simple and effective method to model wetting and drying processes in natural water bodies. The proposed method has been nicknamed \“rough-porous layer”, or RPL. It bears similarities with the so called marsh porosity method, but is simpler to implement, mass conserving and does not affect wave celerity in wet areas. The method can be easily implemented in finite element models, what makes it useful in numerical modeling of natural water bodies with intricate topographies. A standard testing case of a basin with variable slope is used for validations and comparison with other methods. The effectiveness of the RPL is better evaluated in modeling the complex Vitória Bay estuary (Brazil) with its extensive mangrove areas. Keywords: wetting and drying, Vitória Bay estuary, mangrove swamps, finite element method. 1 Introduction Coastal water bodies such as bays and estuarine systems quite often present mangrove swamps, marsh and other wetlands. These regions play an important role in ecosystem productivities contributing to both territorial and marine biodiversity. These wetlands are maintained mainly by periodic drying and wetting processes [4]. Thus, the ability to represent such processes is essential in
In the literature, analytical models have been shown to be extremely useful for estimating the de... more In the literature, analytical models have been shown to be extremely useful for estimating the decay rates of coliform as fecal indicator microorganisms, providing reliable predictions of bathing conditions in coastal and continental waters. Although a number of different formulations have been developed in the literature, each one may only be suitable for specific environments, and no comparison between these methods has ever been carried out. In the present article, a comparative analysis of bacterial decay models, calculated by eight different formulations, was performed in coastal outfall plumes, considering identical environmental conditions of solar radiation, temperature and salinity. A statistical approach was applied to identify the differences in means and in behaviors of the results obtained in the various simulations. The results indicate good agreement between bacterial decay rates calculated with at least four methods that were considered more reliable, and at least one of the models was shown to be suitable for estimating bacterial decay rates under night-time conditions, considering only the combined influences of temperature and salinity. Moreover, under daytime conditions, it provides consistent decay rates when compared with measurements taken in the field.
... L. da N. Cunha a , Corresponding Author Contact Information , E-mail The Corresponding Author... more ... L. da N. Cunha a , Corresponding Author Contact Information , E-mail The Corresponding Author , Paulo CC Rosman b , Aldo Pacheco Ferreira c ... Turbulent stress is parameterized according to filtering techniques derived from the approach known as large eddy simulation (LES ...
RESUMO A investigação de processos inerentes a um sistema estuarino permite inferir de forma mais... more RESUMO A investigação de processos inerentes a um sistema estuarino permite inferir de forma mais precisa sua complexa dinâmica, possibilitando o balizamento de estratégias de ação em planos de gestão e projetos ambientais em regiões costeiras. Este trabalho apresenta um estudo da hidrodinâmica do Sistema Estuarino de Santos (SP), com enfoque na análise da renovação de suas águas, pelo efeito da maré e pelas vazões fluviais afluentes. Por meio do SisBaHiA ® (Sistema Base de Hidrodinâmica Ambiental) foi implementado um modelo hidrodinâmico computacional para a reprodução dos padrões de circulação do sistema. A partir de simulações com o Modelo de Transporte Euleriano, foram então calculadas as taxas de renovação de suas águas, para os períodos representativos de verão e de inverno. Os resultados, apresentados na forma de mapas e na forma de séries temporais de renovação, indicaram que após 30 dias todo o sistema apresenta uma renovação total maior que 95%. Diferenças sazonais puderam ser verificadas apenas em regiões mais internas do estuário, e.g., no Canal de Piaçaguera. Palavras-chave: hidrodinâmica, modelagem de circulação, SisBaHiA ®. Water renewal analysis of the Santos Estuarine System using computational modeling ABSTRACT The investigation of processes inherent in an estuary system allows us to infer more precisely its complex dynamics, assisting in the development of action strategies for environmental management plans and projects in coastal areas. This paper describes a hydrodynamic study of the Santos Estuarine System (São Paulo State, Brazil), focused on its water renewal analysis. A computational model was implemented using SisBaHiA ® (Base System for Environmental Hydrodynamics) in order to reproduce the hydrodynamic patterns of the system. Simulations based on Eulerian Transport Model were performed to compute renewal rates for summer and winter representative periods. Results presented on maps and time series indicated that after 30 days the entire system has a total renewal greater than 95%.
The evaluation of wastewater concentrations in coastal environments has to be accurate for water ... more The evaluation of wastewater concentrations in coastal environments has to be accurate for water quality control. The description of the physical process in a comprehensive model is a complex task. Due to the different spatial and temporal scales involved, the use of different numerical models is required: far-field hydrodynamic models; near-field and pollutant transport models. In this paper, a coupled application of these models is described. Capabilities and limitations of modelling techniques applied to wastewater mixing and dispersion from submerged multiport discharges are discussed for environmental impact analysis. The recommended procedure combines a near-field mixing zone model, such as NRFIELD, with the Lagrangian far-field flow and water quality models within SisBaHia ® (http://www.sisbahia.coppe.ufrj.br/). The results showed that the model coupling improves the description and analysis of treated wastewater discharges over large scales. This allows a more realistic evaluation of the environmental impact due to domestic sewage discharges in coastal waters.
A procedure for the optimisation of hydrokinetic turbine array layout through surrogate modelling... more A procedure for the optimisation of hydrokinetic turbine array layout through surrogate modelling is introduced. The method comprises design of experiments, computational fluid dynamics simulations, surrogate model construction, and constrained optimisation. Design of experiments are used to build polynomial and Radial Basis Function surrogates as functions of two design parameters: inter-turbine longitudinal and lateral spacing, with a view to approximating the capacity factor of turbine arrays with inline and staggered layouts, each of which having a fixed number of turbines. For this purpose, two scenarios have been used as case studies, considering uniform and non-uniform free-stream flows. The major advantage of this method in comparison to those reported in the literature is its capability to analyse different design parameter combinations that satisfy optimality criteria in reasonable computational time, while taking into account complex floweturbine interactions and different turbine types.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2014
ABSTRACT This paper presents a simple and effective method to model the wetting and drying of coa... more ABSTRACT This paper presents a simple and effective method to model the wetting and drying of coastal areas by the tide. The approach considers an equivalent "rough-porous layer" (RPL), wetting and drying method. The method can be easily implemented in finite elements, which makes it useful in numerical modeling of natural water bodies with intricate topographies. Some benchmark tests are devised to examine the performance and robustness of the method at extreme conditions, with satisfactory results. Finally, the effectiveness of the RPL is evaluated in modeling the complex Vitória Bay in Brazil, with its extensive mangrove areas, where the predicted variations in the inundation areas and the velocity fields were reproduced more accurately for different stages of the tide. At field measurement sites, the predicted water levels and velocities agreed favorably with the measured data.
ABSTRACT This paper presents a simple and effective method to model wetting and drying processes ... more ABSTRACT This paper presents a simple and effective method to model wetting and drying processes in natural water bodies. The proposed method has been nicknamed \“rough-porous layer”, or RPL. It bears similarities with the so called marsh porosity method, but is simpler to implement, mass conserving and does not affect wave celerity in wet areas. The method can be easily implemented in finite element models, what makes it useful in numerical modeling of natural water bodies with intricate topographies. A standard testing case of a basin with variable slope is used for validations and comparison with other methods. The effectiveness of the RPL is better evaluated in modeling the complex Vitória Bay estuary (Brazil) with its extensive mangrove areas. Keywords: wetting and drying, Vitória Bay estuary, mangrove swamps, finite element method. 1 Introduction Coastal water bodies such as bays and estuarine systems quite often present mangrove swamps, marsh and other wetlands. These regions play an important role in ecosystem productivities contributing to both territorial and marine biodiversity. These wetlands are maintained mainly by periodic drying and wetting processes [4]. Thus, the ability to represent such processes is essential in
In the literature, analytical models have been shown to be extremely useful for estimating the de... more In the literature, analytical models have been shown to be extremely useful for estimating the decay rates of coliform as fecal indicator microorganisms, providing reliable predictions of bathing conditions in coastal and continental waters. Although a number of different formulations have been developed in the literature, each one may only be suitable for specific environments, and no comparison between these methods has ever been carried out. In the present article, a comparative analysis of bacterial decay models, calculated by eight different formulations, was performed in coastal outfall plumes, considering identical environmental conditions of solar radiation, temperature and salinity. A statistical approach was applied to identify the differences in means and in behaviors of the results obtained in the various simulations. The results indicate good agreement between bacterial decay rates calculated with at least four methods that were considered more reliable, and at least one of the models was shown to be suitable for estimating bacterial decay rates under night-time conditions, considering only the combined influences of temperature and salinity. Moreover, under daytime conditions, it provides consistent decay rates when compared with measurements taken in the field.
... L. da N. Cunha a , Corresponding Author Contact Information , E-mail The Corresponding Author... more ... L. da N. Cunha a , Corresponding Author Contact Information , E-mail The Corresponding Author , Paulo CC Rosman b , Aldo Pacheco Ferreira c ... Turbulent stress is parameterized according to filtering techniques derived from the approach known as large eddy simulation (LES ...
RESUMO A investigação de processos inerentes a um sistema estuarino permite inferir de forma mais... more RESUMO A investigação de processos inerentes a um sistema estuarino permite inferir de forma mais precisa sua complexa dinâmica, possibilitando o balizamento de estratégias de ação em planos de gestão e projetos ambientais em regiões costeiras. Este trabalho apresenta um estudo da hidrodinâmica do Sistema Estuarino de Santos (SP), com enfoque na análise da renovação de suas águas, pelo efeito da maré e pelas vazões fluviais afluentes. Por meio do SisBaHiA ® (Sistema Base de Hidrodinâmica Ambiental) foi implementado um modelo hidrodinâmico computacional para a reprodução dos padrões de circulação do sistema. A partir de simulações com o Modelo de Transporte Euleriano, foram então calculadas as taxas de renovação de suas águas, para os períodos representativos de verão e de inverno. Os resultados, apresentados na forma de mapas e na forma de séries temporais de renovação, indicaram que após 30 dias todo o sistema apresenta uma renovação total maior que 95%. Diferenças sazonais puderam ser verificadas apenas em regiões mais internas do estuário, e.g., no Canal de Piaçaguera. Palavras-chave: hidrodinâmica, modelagem de circulação, SisBaHiA ®. Water renewal analysis of the Santos Estuarine System using computational modeling ABSTRACT The investigation of processes inherent in an estuary system allows us to infer more precisely its complex dynamics, assisting in the development of action strategies for environmental management plans and projects in coastal areas. This paper describes a hydrodynamic study of the Santos Estuarine System (São Paulo State, Brazil), focused on its water renewal analysis. A computational model was implemented using SisBaHiA ® (Base System for Environmental Hydrodynamics) in order to reproduce the hydrodynamic patterns of the system. Simulations based on Eulerian Transport Model were performed to compute renewal rates for summer and winter representative periods. Results presented on maps and time series indicated that after 30 days the entire system has a total renewal greater than 95%.
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