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• An adaptive finite point method for aeroelastic analysis

  E. Ortega, E. Oñate, S. Idelsohn

  (2011). Research Report, Nº PI368

  
  

  Abstract

  An adaptive Finite Point Method (FPM) for solving aeroelastic compressible flow problems is presented. The numerical methodology is based on a meshless upwind-biased discretization of the Euler equations, written in arbitrary Lagrangian-Eulerian (ALE) form, and integrated in time by means of a dual-time steeping technique. This procedure allows achieving accurate solutions circumventing stability constraints of time marching schemes but profiting from its explicit features. In order to exploit the meshless potential of the method, the domain deformation approach implemented is based on the spring network analogy and ''h''-adaptivity is also employed in the computations. Several numerical examples involving typical aeroelastic problems illustrate the performance of the proposed technique. Moreover, evidence about the computational cost and parallel performance of the method is given.

  Abstract
  An adaptive Finite Point Method (FPM) for solving aeroelastic compressible flow problems is presented. The numerical methodology is based on a meshless upwind-biased discretization [...]

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• Analysis of fluid-soil-structure interaction problems with the Particle Finite Element Method (PFEM)

  E. Oñate, M. Celigueta, S. Idelsohn, F. Salazar, A. Larese, R. Rossi, B. Suárez, R. Morán

  (2012). Research Report, Nº PI374

  
  

  Abstract

  We present some developments in the Particle Finite Element Method (PFEM) for analysis of coupled problems in mechanics involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of material points in both the fluid and the solid domains (the later including soil/rocks and structures). A mesh connects the particles (nodes) defining the discretized domain where the governing equations for each of the constituent materials are solved as in the standard FEM. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present several examples of application of the PFEM to solve FSSI problems such as the motion of rocks by water streams, the erosion of river beds, the stability of breakwaters and constructions under sea waves, the falling of landslides on houses and into a reservoir and the failure of rockfill dams in overspill situations.

  Abstract
  We present some developments in the Particle Finite Element Method (PFEM) for analysis of coupled problems in mechanics involving fluid-soil-structure interaction (FSSI). [...]

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• Unified updated Lagrangian formulation for the analysis of quasi and fully incompressible fluids and solids and their interaction via a partitioned scheme and the PFEM

  A. Franci, E. Oñate, J. Carbonell

  (2014). Research Report, Nº PI407

  
  

  Abstract

  In this work, a unified updated Lagrangian formulation for solving fluid-structure interaction (FSI) problems is derived. The mixed velocity-pressure formulation for hypoelastic solids and quasi and fully incompressible Newtonian fluids is obtained as an extension of the velocity formulation derived for a general continuum. The space discretization for the fluid domain is performed via the Particle Finite Element Method (PFEM), where for the solid domain a standard FEM is used. Linear interpolation is used for both the velocity and the pressure fields. The global FSI problem is solved using a Gauss-Seidel iterative scheme. The required stabilization for dealing with incompressible situations is given by an enhanced formulation of the Finite Calculus (FIC) technique [Oñate et al.]. The efficiency of the proposed strategy is tested by solving benchmark FSI problems.

  Abstract
  In this work, a unified updated Lagrangian formulation for solving fluid-structure interaction (FSI) problems is derived. The mixed velocity-pressure formulation for hypoelastic [...]

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• El papel de los modelos numéricos en la investigación y el diseño de aliviaderos de presas

  F. Salazar, J. Mauro, J. Irazábal, A. Larese, . R. Rossi, E. Oñate, R. Morán, M. Toledo

  (2013). Research Report, Nº PI396

  
  

  Abstract

  El Centro Internacional de Métodos Numéricos en Ingeniería (CIMNE) es un centro de investigación dependiente del Gobierno de Cataluña y de la Universidad Politécnica de Cataluña creado en 1987. Su principal actividad es el desarrollo y aplicación de métodos numéricos innovadores para resolver problemas prácticos en diversos campos de la ingeniería, y se desarrolla fundamentalmente en el marco de proyectos de investigación nacionales e internacionales. En los últimos años el centro ha participado en diversos proyectos relacionados con la seguridad de presas, fundamentalmente hidráulica, pero también estructural, en cooperación con diversas empresas y organismos públicos de investigación como el CEDEX y la UPM. La presente comunicación describe brevemente los objetivos principales de los mencionados proyectos, haciendo hincapié en cómo la modelación numérica ha contribuido a alcanzarlos. 

  Abstract
  El Centro Internacional de Métodos Numéricos en Ingeniería (CIMNE) es un centro de investigación dependiente del Gobierno de Cataluña y [...]

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• A Particle Finite Element Method (PFEM) for coupled thermal analysis of quasi and fully incompressible flows and fluid-structure interaction

  E. Oñate, A. Franci, J. Carbonell

  (2014). Research Report, Nº PI403

  
  

  Abstract

  We present a Lagrangian formulation for coupled thermal analysis of quasi and fully incompressible flows and fluid-structure interaction (FSI) problems that has excellent mass preservation features. The success of the formulation lays on a residual-based stabilized expression of the mass balance equation obtained using the Finite Calculus (FIC) method. The governing equations are discretized with the FEM using simplicial elements with equal linear interpolation for the velocities, the pressure and the temperature. The merits of the formulation in terms of reduced mass loss and overall accuracy are verified in the solution of 2D and 3D adiabatic and thermally-coupled quasi-incompressible free-surface flow problems using the Particle Finite Element Method (PFEM). Examples include the sloshing of water in a tank and the falling of a water sphere and a cylinder into a tank containing water.

  Abstract
  We present a Lagrangian formulation for coupled thermal analysis of quasi and fully incompressible flows and fluid-structure interaction (FSI) problems that has excellent [...]

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• Lagrangian analysis of multiscale particulate flows with the particle finite element method

  E. Oñate, M. Celigueta, S. Latorre, G. Casas, R. Rossi, J. Rojek

  (2014). Research Report, Nº PI405

  
  

  Abstract

  We present a Lagrangian numerical technique for the analysis of flows incorporating physical particles of different sizes. The numerical approach is based on the Particle Finite Element Method (PFEM) which blends concepts from particle-based techniques and the FEM. The basis of the Lagrangian formulation for particulate flows and the procedure for modelling the motion of small and large particles that are submerged in the fluid are described in detail. The numerical technique for analysis of this type of multiscale particulate flows using a stabilized mixed velocity-pressure formulation and the PFEM is also presented. Examples of application of the PFEM to several particulate flows problems are given.

  Abstract
  We present a Lagrangian numerical technique for the analysis of flows incorporating physical particles of different sizes. The numerical approach is based on the Particle [...]

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• Improving an input of material model in the D-DEMPack package programme in the Kratos application for granular non-cohesive materials

  H. Koszur

  (2015). Research Report, Nº PI412

  
  

  Abstract

  The main objective of this document is to present an idea of calibration tests used to improve an input material model in the DEM simulations in the D-DEMPack package programme in the Kratos application, which is developed in CIMNE. Presented method lets increase the precision and validity of discrete element modeling work. The calibration tests presented in this protocol may be used for granular non-cohesive materials ( for loose, dry granular material).  They concern only the sphere shape of particles. The tests were conducted on couple different  sizes of particles, in this work are presented results for average diameter of grains equal to 5cm (normal distribution with standard deviation equal to 0,05). The results of research may provide a basis for proper computing project data for preparing material model for loose, dry granular material. Tested by the author methods have been developed based on an article [1].

  Abstract
  The main objective of this document is to present an idea of calibration tests used to improve an input material model in the DEM simulations in the D-DEMPack package programme [...]

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• Open tools for electromagnetic simulation programs

  J. Mora, R. Otín, P. Dadvand, E. Escolano, M. Pasenau, E. Oñate

  (2005). Research Report, Nº PI273

  
  

  Abstract

  Computational electromagnetism requires a wide range of numerical methods depending on the application, the topology of the geometry, the frequency and the quality of the solution. Different efforts have been done to develop a universal software package able to deal with any problem, by integrating existing specific modules in the same interface. Nevertheless, modern computational approaches suggest to use a common basic environment, as high level computing lenguage, to be adapted to the requirements done by the end-user. Following this philosophy, this paper proposes three useful computer tools, combining the most usual requirements, to be customised for any electromagnetic problem.

  Abstract
  Computational electromagnetism requires a wide range of numerical methods depending on the application, the topology of the geometry, the frequency and the quality of the [...]

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• Stabilized solution of the multidimensional advection-diffusion-absorption equation using linear finite elements

  E. Oñate, J. Miquel, F. Zárate

  (2005). Research Report, Nº PI269

  
  

  Abstract

  A stabilized finite element method (FEM) for the multidimensional steady state advection-diffusion-absorption equation is presented. The stabilized formulation is based on the modified governing differential equations derived via the Finite Calculus (FIC) method. For 1D problems the stabilization terms act as a nonlinear additional diffusion governed by a single stabilization parameter. It is shown that for multidimensional problems an orthotropic stabilizing diffusion must be added along the principal directions of  curvature of the solution. A simple iterative algorithm yielding a stable and accurate solution for all the range of physical parameters and boundary conditions is described. Numerical results for 1D and 2D problems with sharp gradients are presented showing the effectiveness and accuracy of the new stabilized formulation.

  Abstract
  A stabilized finite element method (FEM) for the multidimensional steady state advection-diffusion-absorption equation is presented. The stabilized formulation is based on [...]

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• El valor del cálculo en los sistemas de ayuda a la toma de decisiones en ingeniería

  E. Oñate

  (2004). Research Report, Nº PI264

  
  

  Abstract

  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables en los nuevos sistemas de ayuda a la toma de decisiones (SAD). Los SAD integran base de datos, métodos de cálculo y módulos de inteligencia artificial, y su utilización se extiende cada día más para ayuda al diseño y gestión de infraestructuras y servicios de ingeniería. En el texto se describen varios desarrollos y aplicaciones recientes de SAD en ingeniería civil. El artículo acaba con una reflexión sobre los límites de los SAD. The paper stresses the value of the computational methods taught in engineering faculties as indispensable tools within the new decision support systems (DSS). The DSS integrate data bases, computational methods and artificial intelligence modules. They are increasingly used for supporting the design and management of civil constructions and services in engineering. The paper describes recent developments and applications of DSS in civil engineering. The text ends up with a discussion on the limits of the DSS. 

  Abstract
  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables [...]

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