JOURNALS

Documents published in Scipedia

• Finite elements versus finite volumes. Is there really a choice?

  O. Zienkiewicz, E. Oñate

  (1992). Non linear computational mechanics. State of the art. P. Wriggers,R. Wagner and E. Stein (eds.), Chapter IV, Beam, Plate and Shell Formulations, pp. 240-254, Springer Verlag

  
  

  Abstract

  The finite volume method appears to be a particular case of finite elements with a non Galerkin weighting. It is course less accurate for self adjoint problems but has some computationally useful features for first order equations involving only surface integrals. For certain problems this is a substational economy and leads to computationally useful approximations.

  Abstract
  The finite volume method appears to be a particular case of finite elements with a non Galerkin weighting. It is course less accurate for self adjoint problems but has some [...]

  • 38
  •  read

• Numerical simulation of industrial sheet forming processes

  E. Oñate

  Monograph CIMNE (1993). M23

  
  

  Abstract
  This monograph presents different finite element based mathematical models and computational methods for numerical simulation of industrial sheet metal forming processes.

  • 0
  •  read

• II International Workshop. Information Technologies and Computing Techniques for the Agro-Food Sector

  E. Balsa, J. Mora, J. Banga, E. Oñate

  Monograph CIMNE (2003). M86

  
  

  Abstract

  This  monographs of proceedings includes all extended abstracts, which will be presented during the AfoT. These presentations will cover a wide range of topics: - Modelling and simulation operations and process plants. - Food process optimisation, scheduling and control. - Food properties measurements and quality control. - Simulation of complex processes, for example those requiring computational fluid dynamics, CFD. - The use of new information technologies to develop decision support sytems.

  Abstract
  This  monographs of proceedings includes all extended abstracts, which will be presented during the AfoT. These presentations will cover a wide range of topics: - [...]

  • 4
  •  read

• Métodos avanzados de cálculo de estructuras de materiales compuestos

  E. Oñate, S. Oller, S. Botello, J. Miquel

  Monograph CIMNE (1991). M3

  
  

  Abstract

  Se presenta una panorámica del estado del arte de los métodos más actuales para análisis de estructuras con materiales compuestos, incidiendo particularmente en los métodos para análisis de vehículos industriales como materiales compuestos

  Abstract
  Se presenta una panorámica del estado del arte de los métodos más actuales para análisis de estructuras con materiales compuestos, incidiendo particularmente [...]

  • 0
  •  read

• Simulación numérica de la aerodinámica de vehículos

  J. Miquel, G. Bugeda, E. Oñate

  Monograph CIMNE (1991). M2

  
  

  Abstract

  Este trabajo analiza las posibilidades de simulación numérica del flujo aerodinámico alrededor de vehículos automotores, desde un doble punto de vista: metodología a utilizar y desarrollo de las aplicaciones que tal tipo de estudios tienen en los vehículos automotores. A lo largo del desarrollo del mismo, quedan patentes una serie de herramientas mediante las cuales es posible realizar tal tipo de simulación numérica. Dichos estudios revisten una gran importancia si se quiere conocer el comportamiento de los vehículos automotores en condiciones de operación, afectando a aspectos tan importantes como seguridad, ruido, estabilidad, consumo de combustible, ventilación, etc.

  Abstract
  Este trabajo analiza las posibilidades de simulación numérica del flujo aerodinámico alrededor de vehículos automotores, desde un doble punto de [...]

  • 26
  •  read

• CFD analysis of the roll movement of a container ship

  J. García-Espinosa, E. Oñate, J. Helmers, M. Chakkor

  Revista de Ingeniería Naval (2004). Vol. 814, pp. 104-108

  
  

  Abstract

  In the present work a novel approach has been developed for the resolution of this problem of analysis of the movement of roll of a ship. The methodology used for this is based on the modification of the differential equations of the fluid dynamics (RANSE equations), including the movement of the free surface, by applying the finite calculus method. The modified equations are solved using an implicit predictor-corrector scheme and the finite element method (FEM). This resolution scheme is considered optimal for these types of problems, both in accuracy and in calculation time. As an example, it should be noted that for typical problems (more than 1,000,000 finite elements) less than 4 hours of CPU are required to solve several cycles of ship movement (Pentium IV). This allows the analysis of an array of tests in a few days or even hours, having a computer network or sufficient computing power.

  Abstract
  In the present work a novel approach has been developed for the resolution of this problem of analysis of the movement of roll of a ship. The methodology used for this is [...]

  • 27
  •  read

• Desarrollos y aplicaciones de modelos de fractura en la escuela de ingenieros de caminos de Barcelona

  E. Oñate

  Anales de Mecánica de Fractura (2000). Vol. 17, pp. 127-154

  
  

  Abstract

  El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos en la Escuela de Ingenieros de Caminos de Barcelona (EICB) durante los últimos quince años para el análisis no lineal de estructuras. La motivación fundamental para el desarrollo de estos modelos se centra en el análisis de la seguridad de estructuras de hormigón en masa y armado. La mayor parte de los modelos se basan en la teoría de daño continuo y utilizan el método de los elementos finitos para la solución numérica. Los modelos de daño se han extendido y aplicado también con éxito al análisis de diversas estructuras de edificios históricos. Los desarrollos más recientes de estos modelos en la EICB incluyen la predicción de fenómenos de localización en estructuras de hormigón y el análisis del comportamiento no lineal de estructuras con materiales compuestos. De todos estos modelos se presentan en el artículo unas breves pinceladas, las aplicaciones más relevantes y las referencias donde pueden encontrarse los detalles sobre cada caso.

  Abstract
  El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos [...]

  • 0
  •  read

• A finite element model for fluid–structure interaction problems involving closed membranes, internal and external fluids

  P. Ryzhakov, E. Oñate

  Comput. Methods Appl. Mech. Engrg., (2017). Vol. 326, pp. 422-445

  
  

  Abstract

  In this paper we propose a Finite Element model for analyzing closed membranes (“bags”) interacting with internal and external (surrounding) fluids. The approach is based on embedding a Lagrangian monolithic model describing the membrane containing an internal fluid into an Eulerian external fluid model. The combination of kinematic frameworks allows us to accurately track the location of the membrane and naturally represent flow variables discontinuities across it. In order to obtain stable coupling for membrane materials with low density, a slight fluid compressibility is assumed. The coupling between the membrane and the internal fluid is automatically accounted for by a monolithic set-up. The filled membrane and the external fluid are coupled in a Dirichlet–Neumann fashion. The model is validated in several numerical examples and its potential application to a civil engineering problem of coast protection via water-filled bag reefs is shown.

  Abstract
  In this paper we propose a Finite Element model for analyzing closed membranes (“bags”) interacting with internal and external (surrounding) fluids. The approach [...]

  • 4
  •  read

• Cool steam method for desalinating seawater

  P. Arnau, N. Navarro, J. Soraluce, J. Martínez-Iglesias, J. Illas, E. Oñate

  Water (2019). Vol. 11 (11), 16 pp.

  
  

  Abstract

  Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with substantially low energy consumption. LTTD consists of distilling at low temperatures by lowering the working pressure and making the most of low-grade heat sources (either natural or artificial) to evaporate water and then condensate it at a cooler heat sink. To perform the process, an external heat source is needed that provides the latent heat of evaporation and a temperature gradient to maintain the distillation cycle. Depending on the available temperature gradient, several stages can be implemented, leading to a multi-stage device. The cool steam device can thus be single or multi-stage, being raw water fed to every stage from the top and evaporated in contact with the warmer surface within the said stage. Acting as a heat carrier, the water vapor travels to the cooler surface and condensates in contact with it. The latent heat of condensation is then conducted through the conductive wall to the next stage. Net heat flux is then established from the heat source until the heat sink, allowing distilling water inside every parallel stage.

  Abstract
  Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with [...]

  • 3
  •  read

• PFEM formulation for thermo-coupled FSI analysis. Application to nuclear core melt accident

  A. Franci, E. Oñate, J. Carbonell, M. Chiumenti

  Comput. Methods Appl. Mech. Engrg., (2017). Vol. 325, pp. 711-732

  
  

  Abstract

  The aim of this paper is to present a Lagrangian formulation for thermo-coupled fluid–structure interaction (FSI) problems and to show its applicability to the simulation of hypothetical scenarios of a nuclear core melt accident. During this emergency situation, an extremely hot and radioactive lava-like material, the corium, is generated by the melting of the fuel assembly. The corium may induce collapse of the nuclear reactor devices and, in the worst case, breach the reactor containment and escape into the environment. This work shows the capabilities of the proposed formulation to reproduce the structural failure mechanisms induced by the corium that may occur during a meltdown scenario. For this purpose, a monolithic method for FSI problems, the so-called Unified formulation, is here enhanced in order to account for the thermal field and to model phase change phenomena with the Particle Finite Element Method (PFEM). Several numerical examples are presented. First, the convergence of the thermo-coupled method and phase change algorithm is shown for two academic problems. Then, two complex simulations of hypothetical nuclear meltdown situations are studied in 2D as in 3D.

  Abstract
  The aim of this paper is to present a Lagrangian formulation for thermo-coupled fluid–structure interaction (FSI) problems and to show its applicability [...]

  • 5
  •  read