Documents published in Scipedia

• Exploring Plasticity Material Models in Level-Set Topology Optimization

  M. Pozzi, A. Guibert, A. Kim, F. Braghin

  ECCOMAS 2024.

  
  

  Abstract

  This work investigates various elastoplastic material models in topology optimiza tion. A novel topology optimization framework using the level-set method and COMSOL Multi physics is proposed to handle the complexities introduced by nonlinear material behaviors. This method broadens the range of applicable plasticity models and streamlines nonlinear analysis in topology optimization.

  Abstract
  This work investigates various elastoplastic material models in topology optimiza tion. A novel topology optimization framework using the level-set method and COMSOL Multi [...]

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• Aero-Structural Design of a Medium-Altitude Medium-Endurance Fixed Wing UAV

  P. Cardoso, A. Marta, N. Matos

  ECCOMAS 2024.

  
  

  Abstract

  The UAV market is currently very populated, driving the manufacturers to design more efficient solutions to obtain a competitive edge. A cost-effective approach is to improve ex isting products using new technologies and design tools. This work addresses the desire of a UAV manufacturer to develop a growth version of an existing Medium-Altitude Medium-Endurance (MAME) Unmanned Aerial Vehicle (UAV). To that end, the aerostructural optimization of the wing is performed using coupled high-fidelity Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD). Gradient-based optimization fed with derivatives of functions of interest computed using the adjoint method are used for computational efficiency. The coupled problem is posed in the aerostructural optimization framework, targeting for max imum aircraft range, being the solution a result of the concurrent discipline analyses. The set of design variables include wing twist distribution, using the free-form deformation approach, material thicknesses and carbon fibre orientations. The optimized wing geometry exhibits a gain of 5% in aircraft range, with 2% better aerodynamic efficiency (L/D) and 63% wing weight reduction. The impact of multilayer composite manufacturing constraints, namely adjacency of ply angles in neighbouring regions and the orthogonality between ply angles, was found not to be significant. The studies identified weaknesses of the baseline wing and provided meaningful engineering insights for the next generation MAME UAV design

  Abstract
  The UAV market is currently very populated, driving the manufacturers to design more efficient solutions to obtain a competitive edge. A cost-effective approach is to improve [...]

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• El repte del finançament de la dependència a Catalunya mitjançant l’avançament dels lloguers, mantenint la propietat de l’habitatge

  D. Igual

  4rceec (2025). Vol. Finances per una transició sostenible, 101

  
  

  Abstract

  El fort impacte demogràfic a curt termini derivat dels augments del nombre de persones grans i de l’esperança de vida planteja un escenari sense precedents pel que fa al finançament de les depeses que requereixen les persones més grans, amb dependència. En aquests darrers anys de la vida cal fer front a un augment molt important de les despeses, que no es poden assumir amb els ingressos recurrents de les pensions. Aquest fet, conjuntament amb la manca de previsió individual i les limitacions de les administracions per donar aquesta cobertura, plantegen la necessitat de cercar noves alternatives. La proposta plantejada en aquest treball consisteix en una innovació que pot ajudar a donar sostenibilitat al sistema, ja que un elevat percentatge dels ciutadans disposen d’un habitatge en propietat susceptible de facilitar la liquiditat necessària mitjançant l’avançament de lloguers per fer front al pagament de les despeses de la dependència.

  Abstract
  El fort impacte demogràfic a curt termini derivat dels augments del nombre de persones grans i de l’esperança de vida planteja un escenari sense precedents [...]

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• Diagnosi de mobilitat i proposta de canvi ferroviari català.

  S. Montero, J. Sisó, D. Jaumandreu

  4rceec (2025). Vol. Infraestructures i gestió sostenible del territori, 162

  
  

  Abstract
  Proposa la planificació bàsica del ferrocarril a Catalunya.

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• Finite Element Formulations for Axisymmetric Solids: A New Approach Based on the Petrov-Galerkin Method

  F. Zähringer, P. Betsch

  ECCOMAS 2024.

  
  

  Abstract

  The sensitivity of conventional finite element formulations to distorted meshes is a well-known problem. In this work, it is investigated whether an 8-node Petrov-Galerkin f inite element formulation can reduce this mesh-sensitive behavior when simulating linear-elastic axisymmetric problems. The numerical investigations show that the Petrov-Galerkin formulation exhibits significantly better behavior than the Bubnov-Galerkin formulation in certain cases. However, the results also indicate that this is not generally the case.

  Abstract
  The sensitivity of conventional finite element formulations to distorted meshes is a well-known problem. In this work, it is investigated whether an 8-node Petrov-Galerkin [...]

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• High-order Flux Reconstruction schemes for turbulent combustion

  R. TAMOU, J. BOHBOT, J. COATLÉVEN, V. PERRIER, Q. Tran

  ECCOMAS 2024.

  
  

  Abstract
  Download

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• A Multi-layered Integral Approach to the de-icing process

  H. Beaugendre, A. Benoit, F. Morency, M. Parisot

  ECCOMAS 2024.

  
  

  Abstract

  The modification of the shallow water icing model to handle de-icing phenomenon is the main focus of this study. As stated in the original model [1], the runback water is modeled utilizing a lubrication assumption for the water film velocity profile. A constant film temperature Tf(t,x) is then calculated under the thin-film hypothesis. Unlike the simplified icing model, the temperature field within the ice layer Tice(t,x,z) is no longer assumed to be constant. Instead, a temperature profile is utilized, enabling the generation of a static film on the wall when a heat conduction source term from a resistance is present [2]. A Temperature profile Ts(t,x,z) is also used in the static film layer if the model predicts the occurrence of this state. In the energy equation for both the solid ice and liquid portion of the static water film, transverse transfers are not considered, a 1D heat equation is then resolved. An integral approach and proper boundary conditions are used to close the problem. The validity of the integral method deteriorates as the thickness over which vertical integration is performed increases. To avoid this problem, a multi-layer approach is proposed. The thickness of the ice block is then divided into three layers of identical thickness. The purpose of this study is to offer a straightforward and robust method suitable for conducting industrial test cases. The model will first be introduced, followed by a description of the numerical approach. Subsequently, validation test cases will be conducted. Realistic de-icing scenarios will then be designed to evaluate the model [3]. Additionally, non uniform roughness effects will be examined.

  Abstract
  The modification of the shallow water icing model to handle de-icing phenomenon is the main focus of this study. As stated in the original model [1], the runback water is [...]

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• Calibration of Heston Stochastic Local Volatility Model by Numerical Solution of Nonlinear Fokker-Planck Equation

  S. Stoykov

  ECCOMAS 2024.

  
  

  Abstract

  The Fokker-Planck partial differential equation is used to compute the probability density function of the Heston stochastic local volatility model. The solution of the Fokker Planck equation is required for the calibration of the leverage function, which plays an important role in the Heston stochastic local volatility model. The current study describes a numerical method for solving the nonlinear Fokker-Planck partial differential equation. The solution is demonstrated to converge to the one generated from the implied volatility surface by comparing call option prices.

  Abstract
  The Fokker-Planck partial differential equation is used to compute the probability density function of the Heston stochastic local volatility model. The solution of the Fokker [...]

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• Immersed boundary methods for high-order discretization of the compressible Reynolds Averaged Navier-Stokes equations

  D. Lodares, J. Manzanero, E. Ferrer, E. Valero

  ECCOMAS 2024.

  
  

  Abstract

  The Immersed Boundary Method (IBM) presents clear advantages for CFD simu lation of compressible ows around complex geometries. In contrast to the standard body- tted approach, in which meshes are designed to conform to geometries, the IBM treats solid obsta cles via local modi cation of the governing equations. Popular modi cations rest on adding volumetric penalization terms to those mesh cells that are covered by immersed bodies [1] or on imposing special boundary conditions on mesh faces surrounding them [2]. In the context of the nodal Discontinuous Galerkin Spectral Element Method (DGSEM), one can also apply subcell based limiting strategies to further discretize the immersed mesh cells employing a compatible low-order method [3]. In this paper, we present a comparison between these three techniques in a high-order setting to solve compressible ows around 2D geometries using the RANS equations with the Spalart-Allmaras one-equation turbulence model. Our results show that introducing wall model-based terms is necessary for IBM formulations to yield correct RANS ow elds, and suggest that subcell-based limiting in the context of IBM can be advantageous in terms of convergence while maintaining solution accuracy.

  Abstract
  The Immersed Boundary Method (IBM) presents clear advantages for CFD simu lation of compressible ows around complex geometries. In contrast to the standard body- tted approach, [...]

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• Local Timestep Super-Time-Stepping Integration Methods Applied to Heat and Mass Transfer in Anisotropic Porous Media

  N. Dellinger, G. Dufour, X. Lamboley, L. Reboul, F. Rogier

  ECCOMAS 2024.

  
  

  Abstract

  In fire safety problems, the simulation of the thermal degradation of anisotropic porous materials is complex due to the large amplitudes of time and space scales. Degraded areas where temperature increases and gas transport occurs might be very localised, sadly reducing the overall stability of numerical solvers and increasing the computation time. This can be mitigated thanks to Super-Time-Stepping methods, which are based on the use of a multi-step explicit scheme. In this study, these methods are first presented and their advantage to handle diffusion-advection problems such as the thermal degradation of anisotropic porous materials are emphasized on a simple use case. Then, a possible acceleration of the computation by using local timestep Super-Time-Stepping methods, particularly adapted to the heterogeneous problems previously mentioned, is discussed.

  Abstract
  In fire safety problems, the simulation of the thermal degradation of anisotropic porous materials is complex due to the large amplitudes of time and space scales. Degraded [...]

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