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The Journal contains scientific and technical material of broader interest in the areas of theoretical, experimental and computational hydraulics and fluid mechanics in various fields of application (rivers, coasts, environment, structures and industrial flows). This may also include results of field studies and interdisciplinary studies. Further included is publication of state-of-the-art papers, information which is suitable for the end-user (design and consultancy) and forum articles. Discussions to papers and technical notes are welcomed. The scope of the Journal covers the fields in which IAHR is active.
The Journal of Hydraulic Research has been published (currently six issues per year) since 1964 by IAHR and is distributed to all IAHR Members as part of the Membership Subscription, together with the IAHR HydroLink newsletter. JHR is published in print and electronic format. Abstracts are available on-line from 1996,and Full papers from 2001.

Abstract of Papers - JHR Volume 48 Issue extra

Foreword: SPH for free-surface flows
by MONCHO GOMEZ-GESTEIRA, BENEDICT D. ROGERS, DAMIEN VIOLEAU, JOSE MARIA GRASSA and ALEX J.C. CRESPO
Vol: 48 / Issue: extra

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State-of-the-art of classical SPH for free-surface flows
by MONCHO GOMEZ-GESTEIRA, BENEDICT D. ROGERS, ROBERT A. DALRYMPLE and ALEX J.C. CRESPO
Vol: 48 / Issue: extra
Smoothed Particle Hydrodynamics (SPH) is the most widely established mesh-free method which has been used in several fields as astrophysics, solids mechanics and fluid dynamics. In the particular case of computational fluid dynamics, the model is beginning to reach a maturity that allows carrying out detailed quantitative comparisons with laboratory experiments. Here the state-of-the-art of the classical SPH formulation for free-surface flow problems is described in detail. This is demonstrated using dam-break simulations in 2-D and 3-D. The foundations of the method will be presented using different derivations based on the method of interpolants and on the moving least-squares approach. Different methods to improve the classic SPH approach such as the use of density filters and the corrections of the kernel function and its gradient are examined and tested on some laboratory cases.
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Smoothed particle hydrodynamics (SPH) simulation of a tuned liquid damper (TLD) with angular motion
by GABRIELE BULIAN, ANTONIO SOUTO-IGLESIAS, LOUIS DELORME and ELKIN BOTIA-VERA
Vol: 48 / Issue: extra
The roll motion response of a single degree of freedom (SDOF) structural system to which a rigid rectangular partially filled liquid tank has been attached is considered. The SDOF structural system with the empty tank is first described with a mathematical model and this model is validated by performing decay experiments as well as experiments in which periodic excitations are applied to the system. The responses are accurately predicted by the model. The accuracy of these predictions allows us to study both experimentally and numerically, with weakly compressible SPH, the performance of the partially filled tank as a tuned liquid damper (TLD). The sloshing flows inside the tank comprise the onset of breaking waves which make the TLDs devices extremely difficult to model, especially for the potential flow multimodal approaches commonly used to simulate these sorts of coupled systems. In order to characterise the wave breaking effects on the response curves, tests have been performed with liquids of different viscosity, the increasing viscosity preventing the onset of breaking waves. The capabilities of SPH to treat this coupling problem are assessed and the results show that SPH is able to capture a substantial part of the physics involved in the addressed phenomena but further work remains still to be done relating to a more accurate treatment of the laminar viscosity and turbulence effects.
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Free surface flows simulations in Pelton turbines using an hybrid SPH-ALE method
by JEAN-CHRISTOPHE MARONGIU, FRANCIS LEBOEUF, JOËLLE CARO and ETIENNE PARKINSON
Vol: 48 / Issue: extra
AnArbitrary Lagrange Euler (ALE) description of fluid flows is used together with the meshless numerical method Smoothed Particle Hydrodynamics (SPH) to simulate free surface flows. The ALE description leads to an hybrid method that can be closely connected to the finite volume approach. It is then possible to adapt some common techniques like upwind schemes and preconditioning to remedy some of the well known drawbacks of SPH like stability and accuracy. An efficient boundary treatment based on a proper upwinding of fluid information at the boundary surface is settled. The resulting SPH-ALE numerical method is applied to simulate free surface flows encountered in Pelton turbines.
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Application of weakly compressible and truly incompressible SPH to 3-D water collapse in waterworks
by EUN-SUG LEE, DAMIEN Violeau, Réza Issa and STÉPHANE PLOIX
Vol: 48 / Issue: extra
Two algorithms of the SPH Lagrangian numerical method, the first weakly compressible, the second truly incompressible, are presented and applied to two free-surface three-dimensional flows. The first (schematic) case consists of a water column collapsing in a rectangular tank with a central rectangular obstacle, and allows the comparison and validation of both algorithms. It appears that the incompressible method is superior to predict the total strength experienced by the obstacle, while the weakly compressible method shows weaknesses under this criterion. The second application case, very close to an industrial study, represents a “ski-jump” spillway connecting the reservoir of a river dam to a valley with complex bottom shape. The global flow pattern is compared to laboratory observations from a physical model, leading to satisfactory conclusions which prove SPH has the potential to be a promising method for the design of complex waterworks.
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Hydrodynamics and fluid-structure interaction by coupled SPH-FE method
by PAUL H.L. GROENENBOOM and BRUCE K. CARTWRIGHT
Vol: 48 / Issue: extra
In this contribution the coupling of the Smoothed Particle Hydrodynamics (SPH) method for fluid dynamics to Finite Elements (FE) for structures is discussed. The accuracy of the SPH method for hydrodynamics will be demonstrated by the case of a dam break in a container in which it will be made plausible that the experimentally observed free surface profile is influenced by a wet floor. The application of the coupled SPH-FE method to fluid-structure interaction is proven by the simulation of the drop of a flexible cylinder in water. A novel approach to generate free surface waves in an arbitrary domain and validation for second-order Stokes’ waves will be presented. Practical application of the methodology will be demonstrated by a study on waves inside flooded docks of an Amphibious Transport Ship and by the drop of a large canister into waves.
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SPH on GPU with CUDA
by ALEXIS HÉRAULT, GIUSEPPE BILOTTA and ROBERT A. DALRYMPLE
Vol: 48 / Issue: extra
A Smoothed Particle Hydrodynamics (SPH) method for free surface flows has been implemented on a graphical processing unit (GPU) using the Compute Unified Device Architecture (CUDA) developed by Nvidia, resulting in tremendous speed-ups. The entire SPH code, with its three main components: neighbor list construction, force computation, and integration of the equation of motion, is computed on the GPU, fully exploiting its computational power. The simulation speed achieved is one to two orders of magnitude faster than the equivalent CPU code. Example applications are shown for paddle-generated waves in a basin and a dam-break wave impact on a structure. GPU implementation of SPH permits high resolution SPH modeling in hours and days rather than weeks and months on inexpensive and readily available hardware.
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SPH modelling of water waves generated by submarine landslides
by TATIANA CAPONE, ANDREA PANIZZO and JOE J. MONAGHAN
Vol: 48 / Issue: extra
The present work introduces a numerical representation of the rheological non Newtonian Bingham model by means of the Smoothed Particle Hydrodynamics (SPH) approach. The model is first re-written using the SPH formalism. Then, it is tested using an annular viscometer test case. Finally, the generation of tsunami waves due to underwater landslide is faced, considering the experimental work of Rzadkiewicz et al. (1997). The implemented rheological SPH model is used to simulate the landslide deformation, and its interaction with water, thus simulating also the generation and propagation of surface tsunami waves.
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SPHysics-FUNWAVE hybrid model for coastal wave propagation
by MUTHUKUMAR NARAYANASWAMY, ALEJANDRO JACOBO CABRERA CRESPO, MONCHO GÓMEZ-GESTEIRA and ROBERT ANTHONY DALRYMPLE
Vol: 48 / Issue: extra
It is difficult to study the process of wave propagation from the deep ocean to the nearshore region using a single model due to the presence of multiple scales both in time and in space. Numerical models based on the Boussinesq equations are well known to accurately propagate waves from intermediate water depth to the nearshore region. Since they are 2D models, they are computationally efficient and can be applied to study wave transformations over large domains. Numerical models based on Smoothed Particle Hydrodynamics can inherently capture multiply connected free surfaces and hence can be naturally used to capture breaking free surfaces and estimate breaking induced runup and overtopping. Here, a hybrid model (SPHunwave) is developed combining the main advantages of a Boussinesq model (FUNWAVE) and a SPH model (SPHysics). The details of the coupling procedure along with preliminary validation tests are presented.
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A study of violent sloshing wave impacts using an improved SPH method
by ANDREA COLAGROSSI, GIUSEPPINA COLICCHIO, CLAUDIO LUGNI and MAURIZIO BROCCHINI
Vol: 48 / Issue: extra
The flip-through phenomenon has been observed in several conditions characterized by a steep wave approaching a vertical wall (Peregrine 2003). One of the cases where this phenomenon has been observed and studied experimentally is the sloshing in a partially filled tank. This case has been described in Lugni et al. (2006) and in Faltinsen and Timoka (2009). Those experiments detail the features of the flip-through dynamics with an ad hoc distributions of miniaturized pressure sensors and with the records of a fast video-camera. Here, the same flow conditions have been reproduced numerically with an improved SPH method (cSPH), i.e. with MLS integral interpolators (Fries and Matthies 2003). This allows to solve the Euler equations in the case of free surfaces impacting at a wall. The extremely intense local features of the phenomenon highlight the capabilities and limits of the numerical algorithms proposed.
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Comparison of incompressible and weakly-compressible SPH models for free-surface water flows
by JASON P. HUGHES and DAVID I. GRAHAM
Vol: 48 / Issue: extra
Free surface flows represent a significant problem in computational fluid dynamics (CFD). The difficulties are multiplied when the free surfaces overturn or impact against solid surfaces, especially if air is entrapped in the process. Although many models capable of simulating such flows have been reported in the literature, particle-based methods such as SPH are arguably the most appealing conceptually and intuitively. In this paper, we model water flows with free surfaces.We assume that the flows are incompressible. There are many different implementations of SPH but there are two main approaches for modelling incompressible flows. In weakly-compressible SPH (WCSPH) computations of water flows, fluid pressure is related to particle density using a stiff equation of state. An alternative is incompressible SPH (ISPH). Here, a Poisson equation is solved to determine the pressure in an approach based upon the orthogonal decomposition method frequently used in grid-based methods. Recent work by Lee et al. (2008) has shown that, under certain circumstances, ISPH performs better than WCSPH for several flows. In this paper, we compare WCSPH and ISPH results for two standard dam-break problems and for regular water waves impacting against a vertical wall. Results are compared with experimental data where possible and show qualitative and quantitative agreement. In our version of WCSPH, MLS or Shephard filtering density ‘renormalisation’ methods are used and a variety of boundary condition formulations are tested and it is concluded that in the optimum configuration, WCSPH performs at least as well as ISPH, and in some respects clearly performs better.
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SPH modeling of shallow-water coastal flows
by MATTHIEU DE LEFFE, DAVID LE TOUZÉ and BERTRAND ALESSANDRINI
Vol: 48 / Issue: extra
In the present paper, a Smoothed Particle Hydrodynamics (SPH) modeling of the shallow water equations is presented. The objective of this modeling is to perform flooding simulations involving complex bathymetries of sea bottom and dry land. The formulation is first detailed. Its implementation is then described, including specific procedures making possible to follow the expansion of the fluid domain during flooding simulations. An anisotropic kernel with variable smoothing length is especially used, as well as a periodic redistribution of the particles.A number of validation tests are performed. The model results are first checked on the case of a dam break on a flat dry bottom in one and two dimensions. Then more complex two-dimensional cases are simulated and compared to other models and experiments, e.g. a dam break flooding a slope of complex shape, and a solitary wave running up an island.
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SPH high-performance computing simulations of rigid solids impacting the free-surface of water
by PIERRE MARUZEWSKI, DAVID LE TOUZÉ, GUILLAUME OGER and FRANÇOIS AVELLAN
Vol: 48 / Issue: extra
Numerical simulations of water entries based on a three-dimensional parallelized Smoothed Particle Hydrodynamics (SPH) model developed by Ecole Centrale Nantes are presented. The aim of the paper is to show how such SPH simulations of complex 3D problems involving a free surface can be performed on a super computer like the IBM Blue Gene/L with 8,192 cores of Ecole polytechnique fédérale de Lausanne. The present paper thus presents the different techniques which had to be included into the SPH model to make possible such simulations. Memory handling, in particular, is a quite subtle issue because of constraints due to the use of a variable-h scheme. These improvements made possible the simulation of test cases involving hundreds of million particles computed by using thousands of cores. Speedup and efficiency of these parallel calculations are studied. The model capabilities are illustrated in the paper for two water entry problems, firstly, on a simple test case involving a sphere impacting the free surface at high velocity; and secondly, on a complex 3D geometry involving a ship hull impacting the free surface in forced motion. Sensitivity to spatial resolution is investigated as well in the case of the sphere water entry, and the flow analysis is performed by comparing both experimental and theoretical reference results.
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Simulation of caisson breakwater movement using 2-D SPH
by BENEDICT D. ROGERS, ROBERT A. DALRYMPLE and PETER K. STANSBY
Vol: 48 / Issue: extra
Smoothed Particle Hydrodynamics (SPH) is used to simulate the movement of a caisson breakwater in the surf zone. The open-source code SPHysics is used with a Riemann solver-based formulation. The friction force between the moving caisson and the bed is modelled with a transition from static to dynamic friction force. Results are presented for two-dimensional simulations and compared with experiments for the movement of a caisson breakwater under the forcing of periodic waves. Promising agreement with experimental data is obtained for the displacement and the horizontal forces on the caisson. It is demonstrated that the peak impact forces are better captured using finer resolution and that a Riemann solver-based formulation produces a better agreement with experiment for the predicted caisson displacement than conventional SPH.
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Smoothed particle hydrodynamics model applied to hydraulic structures: a hydraulic jump test case
by DAVID LÓPEZ, ROBERTO MARIVELA and LUIS GARROTE
Vol: 48 / Issue: extra
The capability of Smoothed Particle Hydrodynamics (SPH) to reproduce a mobile hydraulic jump was investigated.A similar case was used to generate different upstream Froude numbers to obtain several jump shapes. A physical model was then constructed in a test flume to check the SPH outcomes. The results showed good agreement for Froude numbers <5. Higher Froude numbers require more sophisticated turbulence closure models to obtain better results. Good outcomes can be achieved with k-ε models, but the computational cost is higher than for basic SPH. Instead, a simple method was implemented to increase the viscosity in areas of higher vorticity. In this case, the main difference is related to the dependence of the viscosity on the vorticity. This approach yielded better adjustment. Finally, it was found that SPH provides correct estimates of the average pressures at the boundaries, but exhibits large dispersion for instantaneous water height values. This problem was considerably attenuated by introduction of a turbulence model.
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