A New Approach to Quantify Shallow Water Hydrologic Exchanges in a Large Regulated River Reach

In this paper we present a new approach to describe the behaviour of a pollutant slick at the sea surface. To this end, we consider that the pollutant and the water are immiscible and we propose a two-layer model where the lower layer corresponds to the water and the upper layer represents the pollutant. Since the dimension of the pollutant slick is generally much smaller than the domain occupied by the sea, we propose to compute the motion of the pollutant with a shallow water model with free boundary only in the domain occupied by the pollutant. To discretize in time the problem with free boundary, we use an ALE formulation coupled with the characteristic method. Then, to solve the space discretized problem, we approximate the pollutant velocity by using a Galerkin method with a special basis which verifies the boundary conditions and simplifies significantly the resolution. Finally we test this work in a real situation: the dam of Calacuccia (Corsica).

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MODE AND WAVENUMBER INVERSION IN SHALLOW WATER USING AN ADJOINT METHOD

Journal of Computational Acoustics ◽

10.1142/s0218396x04002390 ◽

2004 ◽

Vol 12 (04) ◽

pp. 521-542 ◽

Cited By ~ 4

Author(s):

ISABELLE CHARPENTIER ◽

PHILIPPE ROUX

Keyword(s):

Shallow Water ◽

Adjoint Method ◽

Automatic Differentiation ◽

Pressure Field ◽

Water Environment ◽

Specific Treatment ◽

Oceanic Waveguide ◽

New Approach ◽

Vertical Arrays ◽

Shallow Water Environment

Modes and wavenumbers are the principal ingredients that characterize the pressure field in an oceanic waveguide. However, wavenumber and mode inversions are well-known to be a difficult task in underwater acoustics. Moreover, this double inversion has never been performed simultaneously from the same configuration of emitters and receivers. We present a new approach to this problem in a shallow water environment between two vertical arrays of sources and receivers. Starting from a classical modal decomposition of the pressure field, our algorithm focuses on a specific treatment of phase and amplitude variables. The key idea is to run a three-stage optimization by working separately on the phase and amplitude of the acoustic field. The high number of variables of the problem is turned into an advantage by using an adjoint code generated by an Automatic Differentiation software. Numerical results in the presence of noise show that modes and wavenumbers are estimated with a high accuracy.

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New Approach for Assessment of Flexible Risers Interference in Shallow Waters

Volume 4B: Pipeline and Riser Technology ◽

10.1115/omae2013-10936 ◽

2013 ◽

Author(s):

Elton J. B. Ribeiro ◽

Edson L. Labanca ◽

Roberto Alvim ◽

Otavio Veras

Keyword(s):

Shallow Water ◽

Water Depth ◽

Critical Issue ◽

Shallow Waters ◽

Wake Effect ◽

Hydrodynamic Coefficient ◽

New Approach ◽

Campos Basin ◽

Internal Fluid ◽

Flexible Risers

This paper presents a methodology to analyze the risers interference connected to an FPSO, which is using turret moored system in shallow water. It is not feasible in shallow water to use riser free hanging catenary configurations, since there is not enough length in order to dissipate FPSO dynamic response due to wave action, which can cause riser damage at TDP. Furthermore, FPSO static offset is very large, around 30% of water depth, when it is compared with deep water, around 11–12% of water depth. In order to become feasible a large number of risers connected to a FPSO using a turret moored system in shallow water are needed to use compliant configurations, such as: lazy wave, pliant wave and Lazy S. As mentioned above risers compliant configurations are capable to avoid riser damage at TDP, but they present a large lateral motion. Thus, riser interference becomes a critical issue to be overcome. As the applicable standards and rules are not entirely prescriptive about this issue, the riser analyst usually have to adopt independent criteria, such as load cases, internal fluid density, hydrodynamic coefficient considering or not wake effect and clashing criteria (allowable, partially allowable or not). Therefore, the proposed methodology is very robust and was used at FEED studies for FPSO OSX-2/3, both belong to OGX, which are planning to install them at the ending of 2013 in Campos Basin, offshore Brazil.

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Controls of River Dynamics on Residence Time and Biogeochemical Reactions of Hydrological Exchange Flows in A Regulated River Reach

10.31223/osf.io/gqn2w ◽

2019 ◽

Author(s):

Xuehang Song ◽

Xingyuan Chen ◽

John Zachara ◽

Jesus Gomez-Velez ◽

Pin Shuai ◽

...

Keyword(s):

Residence Time ◽

Regulated River ◽

River Dynamics ◽

Exchange Flows ◽

River Reach ◽

Hydrological Exchange

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Discharge hydrograph estimation at upstream-ungauged sections by coupling a Bayesian methodology and a 2-D GPU shallow water model

Hydrology and Earth System Sciences ◽

10.5194/hess-22-5299-2018 ◽

2018 ◽

Vol 22 (10) ◽

pp. 5299-5316 ◽

Cited By ~ 3

Author(s):

Alessia Ferrari ◽

Marco D'Oria ◽

Renato Vacondio ◽

Alessandro Dal Palù ◽

Paolo Mignosa ◽

...

Keyword(s):

Shallow Water ◽

Graphics Processing Units ◽

High Performance ◽

Optimization Procedure ◽

Water Model ◽

Computational Time ◽

Geostatistical Approach ◽

River Reach ◽

Graphics Processing ◽

Flow Propagation

Abstract. This paper presents a novel methodology for estimating the unknown discharge hydrograph at the entrance of a river reach when no information is available. The methodology couples an optimization procedure based on the Bayesian geostatistical approach (BGA) with a forward self-developed 2-D hydraulic model. In order to accurately describe the flow propagation in real rivers characterized by large floodable areas, the forward model solves the 2-D shallow water equations (SWEs) by means of a finite volume explicit shock-capturing algorithm. The two-dimensional SWE code exploits the computational power of graphics processing units (GPUs), achieving a ratio of physical to computational time of up to 1000. With the aim of enhancing the computational efficiency of the inverse estimation, the Bayesian technique is parallelized, developing a procedure based on the Secure Shell (SSH) protocol that allows one to take advantage of remote high-performance computing clusters (including those available on the Cloud) equipped with GPUs. The capability of the methodology is assessed by estimating irregular and synthetic inflow hydrographs in real river reaches, also taking into account the presence of downstream corrupted observations. Finally, the procedure is applied to reconstruct a real flood wave in a river reach located in northern Italy.

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