Infoscience

Thesis

Simulation of Silt Erosion Using Particle-Based Methods

Increasing demand for clean sources of energy have forced electricity providers to paymore attention to their hydropower assets. Silt erosion is a destructive phenomenon that may occur in hydropower plants. The power plant subjected to silt erosion requires more repair and maintenance operations. In severe erosion conditions,machines can be shut down for several times in a working season therefore affecting total production. Hence,mitigation of silt erosion is desired by power plants owners. To this day, there are no accurate instrumentation to monitor silt erosion in hydropower facilities. Moreover, due to the complexity of the phenomena, analytical studies are unable to provide reliablemodels. Meanwhile, there are now studies employing numerical approaches to investigate this phenomena. However, to the best of the author’s knowledge, no erosion model exists in which all the interfering phases are modeled numerically. This work presents a new model for silt erosion in which the fluid flow, solid deformation, mass removal and silt motion are simulated. The fluid flow is assumed viscous and weakly compressible. The solid deformation is found from an elasto-plastic constitutive model with isotropic linear hardening. Silt particles are assumed rigid and spherical and their motions are driven by Newton’s second law. The contact force between silt and solid material is modeled according to theHertz contact theory. Fluid and solid equations are discretized using Finite Volume ParticleMethod (FVPM). The interaction between fluid-silt and fluid-solid is accomplished by boundary particles moving with silt or solid velocity. Applying the no-slip wall condition for fluid flow, hydrodynamic forces directly affect the silt or solid. FVPMis a particle-basedmethodwhich includesmany of the desirable features ofmesh-based finite volumemethods. FVPMuses particle interaction vectors to compute the conservative fluxes exchanged between particles. These vectors are equivalent to the intercell area vectors in themesh-based finite volumemethod. To compute the interaction vectors, either numerical or exact integration is applied. Numerical integration based on quadrature rules is approximate and costly, whereas the exactmethod employing circular top-hat kernel is precise and fast. To date, the exactmethod is developed only for 2-Dcomputations. In thiswork,we innovate a 3-D version of FVPM. Thismethod features rectangular top-hat kernels, a reasonable compromise between efficiency and accuracy. [...]

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