1,721,075 research outputs found
An augmented HLLEM ADER numerical model parallel on GPU for the porous Shallow Water Equations
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3D SPH numerical simulation of the wave generated by the Vajont rockslide
No full textA 3D numerical modeling of the wave generated by the Vajont slide, one of the most destructive ever occurred, is presented in this paper. A meshless Lagrangian Smoothed Particle Hydrodynamics (SPH) technique was adopted to simulate the highly fragmented violent flow generated by the falling slide in the artificial reservoir. The speed-up achievable via General Purpose Graphic Processing Units (GP-GPU) allowed to adopt the adequate resolution to describe the phenomenon. The comparison with the data available in literature showed that the results of the numerical simulation reproduce satisfactorily the maximum run-up, also the water surface elevation in the residual lake after the event.
Moreover, the 3D velocity field of the flow during the event and the discharge hydrograph which overtopped the dam, were obtained
Scenari di Allagamento conseguenti a brecce arginali mediante un modello bidimensionale parallelizzato su scheda video
No full textA general design for a scalable MPI-GPU multi-resolution 2D numerical solver
No full textThis paper presents a multi-GPU implementation of a Finite-Volume solver on a multi-resolution grid. The implementation completely offloads the computation to the GPUs and communications between different GPUs are implemented by means of the Message Passing Interface (MPI) API. Different domain decomposition techniques have been considered and the one based on the Hilbert Space Filling Curves (HSFC) showed optimal scalability. Several optimizations are introduced: One-to-one MPI communications among MPI ranks are completely masked by GPU computations on internal cells and a novel dynamic load balancing algorithm is introduced to minimize the waiting times at global MPI synchronization barriers. Such algorithm adapts the computational load of ranks in response to dynamical changes in the execution time of blocks and in network performances; Its capability to converge to a balanced computation has been empirically shown by numerical experiments. Tests exploit up to 64 GPUs and 83M cells and achieve an efficiency of 90% in weak scalability and 85% for strong scalability. The framework is general and the results of the paper can be ported to a wide range of explicit 2D Partial Differential Equations solvers
An advanced study on discretization-error-based adaptivity in Smoothed Particle Hydrodynamics
No full textThis contribution is concerned with a novel, purely methodological strategy enabling to automatically adjust the local spatial resolution in Smoothed Particle Hydrodynamics (SPH). It is built upon the fact that the accuracy of the SPH interpolation is related to zeroth- and first-order moments. Ensuing from this knowledge, a suitable measure of the SPH spatial discretization error has been derived. Using this measure as an adaptivity criterion allows to dynamically adjust the local resolution in such a way that a uniform distribution of the spatial discretization error over the model domain is achieved. This is demonstrated in the present paper. To that end, the theoretical foundation of the proposed adaptivity criterion is discussed first. After that, its applicability to both SPH fluid and solid simulations is thoroughly examine
Experimental and numerical evaluation of the force due to the impact of a dam-break wave on a structure
Full text linkFlood events caused by the collapse of dams or river levees can have damaging consequences on buildings and infrastructure located in prone areas. Accordingly, a careful prediction of the hydrodynamic load acting on structures is important for flood hazard assessment and potential damage evaluation. However, this represents a challenging task and requires the use of suitable mathematical models. This paper investigates the capability of three different models, i.e. a 2D depth-averaged model, a 3D Eulerian two-phase model, and a 3D Smoothed Particle Hydrodynamics (SPH) model, to estimate the impact load exerted by a dam-break wave on an obstacle. To this purpose, idealised dam-break experiments were carried out by generating a flip-through impact against a rigid squat structure, and measurements of the impact force were obtained directly by using a load cell. The dynamics of the impact event was analyzed and related to the measured load time history. A repeatability analysis was performed due to the great variability typically shown by impact phenomena, and a confidence range was estimated. The comparison between numerical results and experimental data shows the capability of 3D models to reproduce the key features of the flip-through impact. The 2D modelling based on the shallow water approach is not entirely suitable to accurately reproduce the load hydrograph and predict the load peak values; this difficulty increases with the strength of the wave impact. Nevertheless, the error in the peak load estimation is in the order of 10% only, thus the 2D approach may be considered appropriate for practical applications. Moreover, when the shallow water approximation is expected to work well, 2D results are comparable with the experimental data, as well as with the numerical predictions of far more sophisticated and computationally demanding 3D solvers. All the numerical models overestimate the falling limb of the load hydrograph after the impact. The SPH model ensures good evaluation of the long-time load impulse. The 2D shallow water solver and the 3D Eulerian model are less accurate in predicting the load impulse but provide similar results. A sensitivity analysis with respect to the model parameters allows to assess model uncertainty
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