IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2024-03-29T05:31:45ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2018-03-28T13:20:52Z2018-03-28T13:20:52Zhttp://eprints.imtlucca.it/id/eprint/4065This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40652018-03-28T13:20:52ZPartitioned coupling of advection–diffusion–reaction systems and Brinkman flowsWe present a partitioned algorithm aimed at extending the capabilities of existing solvers for the simulation of coupled advection–diffusion–reaction systems and incompressible, viscous flow. The space discretisation of the governing equations is based on mixed finite element methods defined on unstructured meshes, whereas the time integration hinges on an operator splitting strategy that exploits the differences in scales between the reaction, advection, and diffusion processes, considering the global system as a number of sequentially linked sets of partial differential, and algebraic equations. The flow solver presents the advantage that all unknowns in the system (here vorticity, velocity, and pressure) can be fully decoupled and thus turn the overall scheme very attractive from the computational perspective. The robustness of the proposed method is illustrated with a series of numerical tests in 2D and 3D, relevant in the modelling of bacterial bioconvection and Boussinesq systems.Pietro LenardaMarco Paggimarco.paggi@imtlucca.itR. Ruiz Baier2017-09-28T06:24:42Z2017-09-28T06:32:17Zhttp://eprints.imtlucca.it/id/eprint/3804This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38042017-09-28T06:24:42ZComputational and experimental characterization of thermo-oxidative and corrosion phenomena in photovoltaic modulesIrene Berardoneirene.berardone@polito.itMariacristina Gagliardimariacristina.gagliardi@imtlucca.itPietro Lenardapietro.lenarda@imtlucca.itMarco Paggimarco.paggi@imtlucca.it2017-03-01T11:41:43Z2017-03-01T11:41:43Zhttp://eprints.imtlucca.it/id/eprint/3656This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36562017-03-01T11:41:43ZSimulation of reaction-diffusion systems to assess EVA degradation in accelerated and environmental ageing conditions: a tool to design novel accelerated climate testsMariacristina Gagliardimariacristina.gagliardi@imtlucca.itPietro Lenardapietro.lenarda@imtlucca.itMarco Paggimarco.paggi@imtlucca.it2017-03-01T11:37:15Z2017-03-01T11:38:28Zhttp://eprints.imtlucca.it/id/eprint/3655This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36552017-03-01T11:37:15ZA reaction-diffusion formulation to simulate EVA polymer degradation in environmental and accelerated ageing conditionsAmong polymers used as encapsulant in photovoltaic (PV) modules, poly(ethylene-co-vinyl acetate), or EVA, is the most widely used, for its low cost and acceptable performances. When exposed to weather conditions, EVA undergoes degradation that affects overall PV performances. Durability prediction of EVA, and thus of the module, is a hot topic in PV process industry. To date, the literature lacks of long-term predictive computational models to study EVA aging. To fill this gap, a computational framework, based on the finite element method, is proposed to simulate chemical reactions and diffusion processes occurring in EVA. The developed computational framework is valid in either case of environmental or accelerated aging. The proposed framework enables the identification of a correspondence between induced degradation in accelerated tests and actual exposure in weathering conditions. The developed tool is useful for the prediction of the spatio-temporal evolution of the chemical species in EVA, affecting its optical properties. The obtained predictions, related to degradation kinetics and discoloration, show a very good correlation with experimental data taken from the literature, confirming the validity of the proposed formulation and computational approach. The framework has the potential to provide quantitative comparisons of degradation resulting from any environmental condition to that gained from accelerated aging tests, also providing a guideline to design new testing protocols tailored for specific climatic zones.Mariacristina Gagliardimariacristina.gagliardi@imtlucca.itPietro Lenardapietro.lenarda@imtlucca.itMarco Paggimarco.paggi@imtlucca.it2016-12-27T09:12:41Z2016-12-27T09:12:41Zhttp://eprints.imtlucca.it/id/eprint/3613This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36132016-12-27T09:12:41ZA geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminatesA comprehensive computational framework based on the finite element method for the simulation of coupled hygro-thermo-mechanical problems in photovoltaic laminates is herein proposed. While the thermo-mechanical problem takes place in the three-dimensional space of the laminate, moisture diffusion occurs in a two-dimensional domain represented by the polymeric layers and by the vertical channel cracks in the solar cells. Therefore, a geometrical multi-scale solution strategy is pursued by solving the partial differential equations governing heat transfer and thermo-elasticity in the three-dimensional space, and the partial differential equation for moisture diffusion in the two dimensional domains. By exploiting a staggered scheme, the thermo-mechanical problem is solved first via a fully implicit solution scheme in space and time, with a specific treatment of the polymeric layers as zero-thickness interfaces whose constitutive response is governed by a novel thermo-visco-elastic cohesive zone model based on fractional calculus. Temperature and relative displacements along the domains where moisture diffusion takes place are then projected to the finite element model of diffusion, coupled with the thermo-mechanical problem by the temperature and crack opening dependent diffusion coefficient. The application of the proposed method to photovoltaic modules pinpoints two important physical aspects: (i) moisture diffusion in humidity freeze tests with a temperature dependent diffusivity is a much slower process than in the case of a constant diffusion coefficient; (ii) channel cracks through Silicon solar cells significantly enhance moisture diffusion and electric degradation, as confirmed by experimental tests.Pietro Lenardapietro.lenarda@imtlucca.itMarco Paggimarco.paggi@imtlucca.it2016-08-29T09:08:06Z2016-08-29T09:08:06Zhttp://eprints.imtlucca.it/id/eprint/3522This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/35222016-08-29T09:08:06ZA computational method to simulate thermo-oxidative degradation phenomena of poly(ethylene-co-vinyl acetate) used in photovoltaics.Mariacristina Gagliardimariacristina.gagliardi@imtlucca.itPietro Lenardapietro.lenarda@imtlucca.itMarco Paggimarco.paggi@imtlucca.it