Category Archives: Proceedings papers

Multi-GPU, multi-node SPH implementation with arbitrary domain decomposition

E. Rustico, J. Jankowski, A. Hérault, G. Bilotta and C. Del Negro

Abstract: We present a restructured version of GPUSPH, a CUDA-based implementation of SPH. The new version is extended to allow execution on multiple GPUs on one or more host nodes, making it possible to concurrently exploit hundreds of devices across a network, allowing the simulation on larger domains and at higher resolutions. Partitioning of the computational domain is not limited anymore to parallel planes and can follow arbitrary, user-defined shapes at the resolution of individual cells, where the cell is defined by the auxiliary grid used for fast neighbor search. Continue reading

A hardware-accelerated parallel implementation of a two-dimensional scheme for free surface flows

J.A. Jankowski

Abstract: This contribution concerns the verification and performance assessment of a hardware-accelerated parallel implementation of an algorithm for the semi-implicit finite difference method for solving the vertically integrated shallow water equations including a non-linear treatment of wetting and drying and conservative advection schemes. Continue reading

On the representation of bottom shear stress in z-layer models

F. Platzek, G.S. Stelling, J.A. Jankowski, R. Patzwahl

Abstract. Bottom friction plays an important role in modelling river flows. In three-dimensional (3D) models, the vertical discretization is commonly based on σ-layers or z-layers. In this paper we focus on a well-known problem encountered when applying z-layers: local truncation errors in the computation of bottom shear stress and near-bed turbulence along a sloping bottom as e.g. in the case of 3D river simulations. This problem stems from the ‘staircase’ representation of the bottom and results in difficulties in the computation of morphological changes. Continue reading

Very high resolution numerical modelling for inland waterway design

R. Patzwahl, J.A. Jankowski, T. Lege

Abstract. The paper discusses the advantages and disadvantages of numerical modelling of rivers with a grid of very high resolution using the new MPI version of UnTRIM as the computational engine. The main aim of the investigation is to assess the economy of this approach taking especially into account the effort required for the mesh generation and its modification, which is usually laborious in the case of coarser meshes requiring exact reproduction of structure lines defining the flow. Continue reading

Further developments of UnTRIM: parallel implementation and its verification

J.A. Jankowski

Abstract. This contribution deals with further developments of UnTRIM, an unstructured-grid, three-dimensional, semi-implicit finite difference finite volume model for the shallow water equations (Casulli, 2002). Attractive numerical properties of the method like its robustness due to the unlimited stability and successes in practical applications spawned efforts aimed at making the available code fit for the high performance computing in order to address larger, complex problems in hydraulic engineering. Continue reading