1,004 research outputs found
Efficient algebraic multigrid preconditioning of Krylov solvers for an incompressible SPH scheme
No full textEfficient algebraic multigrid preconditioning of Krylov solvers for an incompressible SPH scheme
No full textOn the approximate zeroth and first-order consistency in the presence of 2-D irregular boundaries in SPH obtained by the virtual boundary particle methods
No full textIn this paper, a new method to impose 2-D solid wall boundary conditions in smoothed particle hydrodynamics is presented. The wall is discretised by means of a set of virtual particles and is simulated by a local point symmetry approach. The extension of a previously published modified virtual boundary particle (MVBP) method guarantees that arbitrarily complex domains can be readily discretised guaranteeing approximate zeroth and first-order consistency. To achieve this, three important new modifications are introduced: (i) the complete support is ensured not only for particles within one smoothing length distance, h, from the boundary but also for particles located at a distance greater than h but still within the support of the kernel; (ii) for a non-uniform fluid particle distribution, the fictitious particles are generated with a uniform stencil (unlike the previous algorithms) that can maintain a uniform shear stress on a particle-moving parallel to the wall in a steady flow; and (iii) the particle properties (density, mass and velocity) are defined using a local point of symmetry to satisfy the hydrostatic conditions and the Cauchy boundary condition for pressure. The extended MVBP model is demonstrated for cases including hydrostatic conditions for still water in a tank with a wedge and for curved boundaries, where significant improved behaviour is obtained in comparison with the conventional boundary techniques. Finally, the capability of the numerical scheme to simulate a dam break simulation is also shown. ? 2015 John Wiley & Sons, Ltd
Local Uniform Stencil (LUST) boundary condition for arbitrary 3-D boundaries in parallel smoothed particle hydrodynamics (SPH) models
No full textThis paper presents the development of a new boundary treatment for free-surface hydrodynamics using the smoothed particle hydrodynamics (SPH) method accelerated with a graphics processing unit (GPU). The new solid boundary formulation uses a local uniform stencil (LUST) of fictitious particles that surround and move with each fluid particle and are only activated when they are located inside a boundary. This addresses the issues currently affecting boundary conditions in SPH, namely the accuracy, robustness and applicability while being amenable to easy parallelization such as on a GPU. In 3-D, the methodology uses triangles to represent the geometry with a ray tracing procedure to identify when the LUST particles are activated. A new correction is proposed to the popular density diffusion term treatment to correct for pressure errors at the boundary. The methodology is applicable to complex arbitrary geometries without the need of special treatments for corners and curvature is presented. The paper presents the results from 2-D and 3-D Poiseuille flows showing convergence rates typical for weakly compressible SPH. Still water in a complex 3-D geometry with a pyramid demonstrates the robustness of the technique with excellent agreement for the pressure distributions. The method is finally applied to the SPHERIC benchmark of a dry-bed dam-break impacting an obstacle showing satisfactory agreement and convergence for a violent flow
Factors affecting trust and communication in global virtual teams
No full textAuthor Georgios GousiasMasterarbeit Universität Linz 2022Arbeit auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
Factors affecting trust and communication in global virtual teams
No full textAuthor Georgios GousiasMasterarbeit Universität Linz 2022Arbeit auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
Improved density diffusion term for long duration wave propagation
No full textThis paper presents the applicability of a new density diffusion term recently proposed by Fourtakas et al. [Computers & Fluids, 2019] for the weakly compressible smoothed particle hydrodynamics scheme as part of the DualSPHysics solver. We show that the new density diffusion term is suitable for long duration simulations without the computationally expensive renormalized density gradient usually present in such terms. By using this formulation the higher order terms are computed locally as a hydrostatic density difference that deems the scheme computationally inexpensive. In this study, the diffusion term formulation is shown to reproduce accurately the pressure and velocity field for long duration simulations without any free-surface diffusion or pressure noise. The test cases simulated are a still water (hydrostatic) case, a regular wave generated by a paddle and finally a sloshing tank to demonstrate the applicability of the term with moving boundaries
Improved density diffusion term for long duration wave propagation
No full textThis paper presents the applicability of a new density diffusion term recently proposed by Fourtakas et al. [Computers & Fluids, 2019] for the weakly compressible smoothed particle hydrodynamics scheme as part of the DualSPHysics solver. We show that the new density diffusion term is suitable for long duration simulations without the computationally expensive renormalized density gradient usually present in such terms. By using this formulation the higher order terms are computed locally as a hydrostatic density difference that deems the scheme computationally inexpensive. In this study, the diffusion term formulation is shown to reproduce accurately the pressure and velocity field for long duration simulations without any free-surface diffusion or pressure noise. The test cases simulated are a still water (hydrostatic) case, a regular wave generated by a paddle and finally a sloshing tank to demonstrate the applicability of the term with moving boundaries
Improved density diffusion term for long duration wave propagation
No full textThis paper presents the applicability of a new density diffusion term recently proposed by Fourtakas et al. [Computers & Fluids, 2019] for the weakly compressible smoothed particle hydrodynamics scheme as part of the DualSPHysics solver. We show that the new density diffusion term is suitable for long duration simulations without the computationally expensive renormalized density gradient usually present in such terms. By using this formulation the higher order terms are computed locally as a hydrostatic density difference that deems the scheme computationally inexpensive. In this study, the diffusion term formulation is shown to reproduce accurately the pressure and velocity field for long duration simulations without any free-surface diffusion or pressure noise. The test cases simulated are a still water (hydrostatic) case, a regular wave generated by a paddle and finally a sloshing tank to demonstrate the applicability of the term with moving boundaries
- …
