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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : Numerical analysis and validation of south valencia sewage collection system
Numerical analysis and validation of south valencia sewage collection system
Author : ARNAU BAYÓN-BARRACHINA(1), FRANCISCO JOSÉ VALLÉS-MORÁN(2) & PETRA AMPARO LÓPEZ-JIMÉNEZ(3)
ABSTRACT
The old Sewage Collection System (SCS) of south Valencia, Spain, had to be recently diverted to avoid interference with
the city high-speed railway works. Certain aspects of the proposed modification of this channel are complex from both the
geometric and the hydraulic point of view. Besides, the structure is a unitary collector and must handle torrential flow rates
up to 100m3/s. In the present work, the stretch most prone to suffer from hydraulic issues is numerically analyzed. This
part of the SCS diversion project involves complex sections, critical and subcritical flow regimes, hydraulic jumps, flow
expansions and contractions and other singularities not always easy to address. In order to analyze the hydraulic
performance of the described design, a three-dimensional model based on the open-source CFD platform OpenFOAM is
presented. In this model, turbulence is treated using three widely used RANS approaches, namely: Standard k-epsilon,
RNG k-epsilon and SST k-omega, whose accuracies are compared by means of a sensitivity analysis. Structured meshes
of different element size are tested, and the model sensitivity to this parameter is also studied. The air-water interface
must be accurately defined, as the flow under study is gravity-driven and water depths have to be controlled to avoid flow
pressurization. To do so, an Eulerian-Eulerian volume method is used. As a result, a full physically consistent description
of the flow is achieved and so a wealth of interesting variables can be computed. In order to assess the accuracy of the
numerical model, some variables regarding the water surface level are compared to experimental data. These
experimental results are obtained from a 1/20 scale physical model, where Froude similarity is achieved and scale effects
are proved not to be significant. Good agreement between numerical and experimental results is achieved despite the
complexity of the system under study. In the light of the results, the model proposed can be applied to accurately model
similar hydraulic structures.
File Size : 1,428,499 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 18/08/2015
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