
Ana Maria Ferreira da SilvaQueen's University | QueensU · Department of Civil Engineering
Ana Maria Ferreira da Silva
Ph.D., P.Eng.
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76
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Introduction
Ana Maria Ferreira da Silva currently works at the Department of Civil Engineering, Queen's University.
Skills and Expertise
Publications
Publications (76)
Focusing on the effect of the meandering planform, two functions are investigated by a numerical experiment: the first represents the ratio between the intensities of the resisting forces acting on a meandering flow and its corresponding straight flow; and the second represents the ratio between the intensities of the resisted meandering flow itsel...
The flow in every meandering channel with a specific sinuosity has its own convective pattern. However, most of the previous numerical works did not take this nature as an essential aspect when validating their computed flows, and even some typical works turned out to fail to capture the correct convective patterns of meandering flows. In this pape...
Waste stabilization ponds (WSPs) rely on natural processes to improve water quality. WSPs require less capital or operational resources than traditional treatment and are commonly used in rural communities or for secondary disinfection. Typically, WSPs designs use empirical equations without three-dimensional (3D) circulation, thermal stratificatio...
Waste stabilization ponds (WSPs) are a common wastewater treatment approach throughout the world. Typically, WSPs are designed with the aid of empirical equations that may not incorporate complex hydrodynamics. Whereas numerical models have been presented as an alternative, they have been limited to two dimensions or lacked validation. In the prese...
A new empirical equation for alternate bar height is introduced. It is assumed that the bars are formed under a steady and uniform flow; the stage of interest is that where bars have grown to their fully developed state. The equation is developed on the basis of dimensional considerations and all data available to the authors; the formulation also...
Hyporheic flow, the flow of water through the permeable material immediately surrounding a river, is important for nutrient cycling, dissolved oxygen transport, and contaminant transport. In addition, there is recent concern regarding the role of hyporheic flow on the contamination of rivers following oil spills. To better understand hyporheic flow...
One of the most uncertain hydraulic designs in urban stormwater management concerns sediment control wet ponds as the event mean total suspended sediment concentration that is discharged into a receiving watercourse depends on many complex factors. The primary factors that influence the performance of wet ponds include design storm event volume, se...
This work considers flow past a bar in a gravel stream. A novel experiment detailing the interaction between surface flow and hyporheic flow induced by the bar is presented. The focus is on effects on the mean velocity and turbulence characteristics of the surface flow.
Hyporheic flows induced by bed forms in rivers.
There is disagreement in the literature as to whether a shear stress-based approach can be used to accurately predict sediment transport over dunes. This study aims to address this disagreement. To this end, use is made of an experiment involving the study of naturally formed, fully developed dunes produced in a laboratory flume. The bed shear stre...
Investigation of hydrodynamic patterns within a wastewater stabilization pond to improve treatment modeling
This paper, written to mark the 60th anniversary of the Journal of Hydraulic Engineering, focuses on the nature of meandering flow and its coupling to bed and bank deformation. An outline of the present understanding of the kinematics of meandering flow and how the flow shapes the bed, with a view towards the conditions in real alluvial meandering...
An experimental and numerical study of the turbulent hyporheic and free surface flows associated with a gravel bar is presented. The hyporheic flow is visualized and quantified with the aid of dye injections; and further resolved with the aid of a numerical model. The mean and turbulence characteristics of the free surface flow are analyzed on the...
A stream flowing in alluvium deforms its bed surface, forming ripples, dunes, bars, etc., and, in many instances, it deforms its channel entirely, thereby creating meandering or braiding patterns. It could be said that, in general, an alluvial stream and its deformable boundary undergo a variety of fluvial processes leading to the emergence of a mu...
A new set of laboratory data is used to investigate the bathymetry change of a steep sand dune exposed to waves and high water levels, and subsequently compared to the results of numerical simulations using XBeach.
Bichromatic wave boundary conditions are used to simulate a combined short-wave and long-wave field for two
water level elevations corr...
p class="p1">La creciente necesidad del recurso hídrico para los diferentes usos, tanto en la naturaleza como en las actividades del ser humano, ha estimulado un incremento en el estudio detallado de cada una de las fases del ciclo hidrológico. Costa Rica, un país con muchos ríos a lo largo de todo el territorio y situado en el trópico, tiene mucha...
Predicting the geometric characteristics of a regime channel is of utmost importance in the context of river engineering and management, as regime channels require minimum protection and minimum expenses for their maintenance. There are numerous empirical and analytical methods to predict these geometric characteristics. This paper develops and tes...
This paper originates from a study to evaluate the long term effect of river sediment contamination by oil spills, recently initiated at Queen’s University. The paper presents results of the first phase of the study, dedi-cated to exploring a suitable computational framework for the simulation of hyporheic flow through gravel bars. Results of a ful...
A model solving the RANS equations coupled with the k-ω SST turbulence closure is used to simulate the steady state flow over rough dunes. The results of the numerical model are validated against detailed velocity measurements over fixed rough dunes carried out at Queen's University. Both smooth-wall and rough wall boundary conditions are considere...
The hydraulic interactions of water and sediments in hyporheic zone.
It is generally recognized that large-scale turbulent coherent structures play an important role in the transport of sediment and contaminants in rivers. They are also believed to be related to the origin and development of a variety of fluvial bed and plan forms. While intensive laboratory and field research has been devoted in recent years to the...
This paper presents a review of the present understanding of the kinematics of meandering flow, and its relationship to bed deformation as well as downstream migration and lateral expansion of meander loops. Taking into account the conditions prevailing in natural, low-land alluvial meandering rivers, the paper focuses primarily on the behaviour of...
This paper concerns the prediction of the bed development time of alluvial meandering streams. It is assumed that the stream centreline follows a sine-generated curve; the banks are rigid; the flow is turbulent and subcritical; and the width-to-depth ratio is “large”. The bed is flat at the beginning of an “experiment”. The bed development consists...
Coastal morphological changes occur at different scales and at different rates that depend on the surface wave forcing conditions and mean water level elevations. Storms deliver both energetic waves and elevated mean water levels, and can cause large volumes of sediment to erode and induce major changes over a short time. The present study uses a s...
This paper presents a review of the present understanding of the kinematics of meandering flow, and its relationship to bed deformation as well as downstream migration and lateral expansion of meander loops. Taking into account the conditions prevailing in natural, low-land alluvial meandering rivers, the paper focuses primarily on the behaviour of...
This paper is intended as a contribution towards the development of better predictors of the geometric characteristics of alternate bars. The specific objective of the paper is to introduce a new equation for alternate bar length. It is assumed that the bars are formed under a steady and uniform flow; the bed is flat at the beginning of the experim...
A method to fix movable beds in river-related laboratory research or physical model studies is proposed and investigated. The motivation was to develop a method that would: (1) not involve the use of harsh chemicals and (2) ensure that the granular roughness of the original movable bed was maintained. The method involves coating the surface with a...
In this paper, an attempt is made to explain why, in the absence of geological
constraints, some rivers remain regular, in which case they tend to closely follow
sine-generated curves, while others become irregular. The considerations rest on
the present understanding of physical mechanisms determining both meandering
bed deformation and bank erosi...
This study aims to further the understanding of cross-shore flows, sediment transport and beach evolution by combining physical model results with numerical predictions. The wave and morphological numerical model XBeach will be compared with laboratory results for a variety of erosive conditions, bed shear stresses and near bed velocities to unders...
The existence region plan of alternate bars, multiple bars, meandering and braiding, introduced by da Silva in 1991 and presented in its most recent form by Yalin and da Silva in the 2001 IAHR monograph Fluvial Processes, is updated and revised. For this purpose, the plan is extended by adding available laboratory and field data from the recent lit...
Despite substantial research on various aspects of bed deformation in meandering streams, no systematic effort has yet been made to establish the timescales of the process. Additionally, in past experiments, as a rule, the bed was not monitored throughout the development, which has left undocumented essential features of the growth of meandering po...
This paper concerns the large-scale horizontal coherent structures (HCS’s) in open-channel
flows. In contrast to large-scale vertical coherent structures, HCS’s have not yet been the focus of directed,
systematic studies, and as a result the exact role they play in river morphodynamics remains elusive.
This paper, which is to be viewed as an extens...
On the basis of previous work by the late Professor M. Selim Yalin and the author, the process of self-formation of alluvial streams and the final (equilibrium or regime) geometry of the self-formed stream are considered in the light of thermodynamic principles, including the first and second laws, and the Gibb's equation; the stream is treated as...
The size of the largest horizontal coherent structures (HCSs) of turbulence in open-channel flows is investigated experimentally on the basis of three series of flow velocity measurements. These are further used to explore the dynamics and morphological consequences of HCSs. The flow velocity measurements were carried out in a 21 m long and 1 m wid...
This paper concerns the quantitative evaluation of the time of bed development of alluvial meandering streams. In agreement with the prevailing approach, it is assumed that the stream centerline follows a sine-generated curve; the banks are rigid. The flow is turbulent and subcritical, and the flow width is much larger than the flow depth. The mova...
This paper concerns the location in flow plan of the laterally adjacent erosion–deposition zones (“deeps” and “hills”) in sine–generated meandering streams. The aim of the paper is to gain insight into how the location of the aforementioned erosion–deposition zones is affected by stream sinuosity, as well as other geometric and flow–related paramet...
The effect of channel sinuosity on flow pattern in meandering streams is investigated. The centerlines of the idealized meandering streams under consideration follow sine-generated curves, and the banks are rigid; the flow is turbulent and subcritical. This study focuses on the vertically averaged flow over a flat (horizontal at any cross section)...
Mr. President, Dear colleagues, Ladies and gentlemen, I am very honoured, and deeply grateful to the IAHR Awards Committee and the IAHR Council for making me the recipient of this year's Arthur Thomas Ippen Award. It is a great pleasure for me to be here today to deliver this lecture. It has also been a great pleasure to attend this Congress, which...
The effect of geometric and flow related parameters on the location in flow plan of the laterally adjacent erosion "deeps" and deposition "hills" of meandering streams is investigated. The centerlines of the regular meandering streams follow sine-generated curves; the banks are rigid; the flow is turbulent and subcritical. A series of experimental...
Paper presented at The Seventh International Conference on HydroScience and Engineering (ICHE) hosted by the College of Engineering at Drexel Univeristy on September 10-13, 2006 in Philadelphia, Pennsylvania. The conference theme was IT in the Field of HydroSciences. It included several mini-symposia that emphasized IT topics in HydroSciences and t...
In this paper the numerical simulation of scour by a free falling jet is presented. It is assumed that the flow is two-dimensional, the alluvium is cohesionless, and that at the beginning of a run, i.e. at t = 0, the movable bed is flat. The scour simulation involves three basic steps: simulation of a turbulent flow in the stilling basin of a free...
This paper concerns the initiation and time-development of large-scale plan forms (meandering and braiding) of alluvial streams. The initiation of these forms is attributed to the horizontal macroturbulence of the flow. The subsequent time- development of the so-initiated alluvial forms is attributed to the regime trend - with the streams altering...
A general method for the formulation of flow characteristics which are functions of the Reynolds number of the system is presented. It is assumed that the flow characteristics exhibit a strong variation with the Reynolds number when the Reynolds number is "small," and that they become independent of it when the Reynolds number is "large." The metho...
The present paper concerns the computation of regime channel characteristics in cohesionless alluvium. The computational method proposed rests on the channel formation criterion derived from the thermodynamic principles, and on the expression of the aspect ratio determined in the earlier works of the authors on the basis of zero cross-transport rat...
The meaning of the regime channels is explained and the prominent ways of their investigation are outlined. A particular attention is given to the determination of regime channels by the current "rational" methods: the present paper is the authors' contribution to this approach. The computational method suggested herein rests on the regime channel...
An expression for the friction factor of rough turbulent meandering flows is suggested: flow cross section is rectangular, the plan shape of the meandering channel is sine-generated. This expression gives the value of the friction factor as a function of position (which is determined by, among other factors, the local channel curvature) and channel...
Thesis (Ph. D.)--Queen's University at Kingston, 1995. Includes bibliographical references.
Alternate bars have been explained on the basis of horizontal bursts, which occur in an open-channel turbulent flow. It has been found that the length of alternate bars, namely 6B, is but the length of horizontal bursts producing them. The criteria of their occurrence are also derived and discussed. (from authors' abstract)