Now showing items 1-20 of 282

    • A 8-neighbor model lattice Boltzmann method applied to mathematical-physical equations 

      An, Bo; Bergadà Granyó, Josep Maria (2016-10-26)
      Article
      Open Access
      A lattice Boltzmann method (LBM) 9-bit model is presented to solve mathematical-physical equations, such as, Laplace equation, Poisson equation, Wave equation and Burgers equation. The 9-bit model has been verified by ...
    • A closer look: high-resolution pore-scale simulations of solute transport and mixing through porous media columns 

      Solé Marí, Guillem; Bolster, Diogo; Fernández García, Daniel (2022-01)
      Article
      Restricted access - publisher's policy
      Mixing is pivotal to conservative and reactive transport behaviors in porous media. Methods for investigating mixing processes include mathematical models, laboratory experiments and numerical simulations. The latter have ...
    • A data-driven wall-shear stress model for LES using gradient boosted decision trees 

      Radhakrishnan, Sarath; Adu Gyamfi, Lawrence; Miró Jané, Arnau; Font García, Bernat; Calafell Sandiumenge, Joan; Lehmkuhl Barba, Oriol (Springer Nature, 2021)
      Conference report
      Open Access
      With the recent advances in machine learning, data-driven strategies could augment wall modeling in large eddy simulation (LES). In this work, a wall model based on gradient boosted decision trees is presented. The model ...
    • A dynamic load balancing method for the evaluation of chemical reaction rates in parallel combustion simulations 

      Muela Castro, Jordi; Borrell Pol, Ricard; Ventosa Molina, Jordi; Jofre Roca, Lluís; Lehmkuhl Barba, Oriol; Pérez Segarra, Carlos David (Elsevier, 2019-08-15)
      Article
      Open Access
      The development and assessment of an efficient parallelization method for the evaluation of reaction rates in combustion simulations is presented. Combustion simulations where the finite-rate chemistry model is employed ...
    • A fast and accurate method to solve the incompressible Navier-Stokes equations 

      Idelsohn Barg, Sergio Rodolfo; Nigro, Norberto; Gimenez, Juan; Rossi, Riccardo; Martí, Julio Marcelo (2013-02)
      Article
      Restricted access - publisher's policy
      Purpose: The purpose of this paper is to highlight the possibilities of a novel Lagrangian formulation in dealing with the solution of the incompressible Navier-Stokes equations with very large time steps. Design/meth ...
    • A FEM-DEM technique for studying the motion of particles in non-Newtonian fluids: application to the transport of drill cuttings in wellbores 

      Celigueta Jordana, Miguel Ángel; Deshpande, Kedar M.; Latorre, Salvador; Oñate Ibáñez de Navarra, Eugenio (Springer, 2015-11)
      Article
      Open Access
      We present a procedure for coupling the finite element method (FEM) and the discrete element method (DEM) for analysis of the motion of particles in non-Newtonian fluids. Particles are assumed to be spherical and immersed ...
    • A first assessment of an aerodynamic barrier layer for filtering airborne hygroscopic particles 

      Arias Montenegro, Francisco Javier; Heras Jiménez, Salvador Augusto de las (2021-09-01)
      Article
      Restricted access - publisher's policy
      In this work consideration is given to an aerodynamic concept for filtration of small water droplets such as those caused by an infected person when coughs or sneezes and including airborne hygroscopic particle, and with ...
    • A first estimate for a pressure-retarded osmosis-driven thermosyphon 

      Arias Montenegro, Francisco Javier (2017-12-01)
      Article
      Open Access
      Pressure retarded osmosis (PRO) process and its significance for thermosyphon technology is discussed. In previous work the possibility to drive a thermosyphon by difference of densities from induced salinity gradients ...
    • A first study on an oscillatory flow enclosed in a finite cylinder 

      Panadès i Guinart, Carles (Universitat Politècnica de Catalunya, 2009-09-14)
      Master thesis
      Open Access
      In this preliminar work, an oscillatory flow contained in a closed cylinder is investigated by means of spectral methods. The problem is quite related with the Stokes boundary layer and the major phenomena belong to this ...
    • A fluid-structure interaction solver for the fluid flow through reed type valves 

      González Acedo, Ignacio; Naseri, Alireza; Rigola Serrano, Joaquim; Pérez Segarra, Carlos David; Oliva Llena, Asensio (Institute of Physics (IOP), 2017)
      Conference lecture
      Open Access
      Suction and discharge processes with self actuated valves have a major influence in efficiency and reliability of hermetic reciprocating compressors. Understanding the operation completely in order to enhance compressor's ...
    • A highly portable heterogeneous implementation of a Poisson solver for flows with one periodic direction 

      Alsalti Baldellou, Àdel; Trias Miquel, Francesc Xavier; Álvarez Farré, Xavier; Oliva Llena, Asensio (2021)
      Conference report
      Restricted access - publisher's policy
      The portability of codes has become a major advantage given the continuous development of new architectures for numerical applications, as well as the progressive incorporation of accelerators in modern supercomputers. ...
    • A hybrid parallel numerical model for wave-induced free-surface flow 

      Leftheriotis, Georgios A.; Chalmoukis, Iason A.; Oyarzun Altamirano, Guillermo; Dimas, Athanassios A. (MDPI, 2021-10-04)
      Article
      Open Access
      An advanced numerical model is presented for the simulation of wave-induced free-surface flow, utilizing an efficient hybrid parallel implementation. The model is based on the solution of the Navier–Stokes equations using ...
    • A level-set method for thermal motion of bubbles and droplets 

      Balcázar Arciniega, Néstor; Oliva Llena, Asensio; Rigola Serrano, Joaquim (Institute of Physics (IOP), 2016)
      Conference report
      Open Access
      A conservative level-set model for direct simulation of two-phase flows with thermocapillary effects at dynamically deformable interface is presented. The Navier-Stokes equations coupled with the energy conservation equation ...
    • A level-set model for thermocapillary motion of deformable fluid particles 

      Balcázar Arciniega, Néstor; Rigola Serrano, Joaquim; Castro González, Jesús; Oliva Llena, Asensio (2016-12-01)
      Article
      Open Access
      A new level-set model is proposed for simulating immiscible thermocapillary flows with variable fluid-property ratios at dynamically deformable interfaces. The Navier–Stokes equations coupled with the energy conservation ...
    • A low-dissipation convection scheme for the stable discretization of turbulent interfacial flow 

      Schillaci, Eugenio; Jofre Cruanyes, Lluís; Balcázar Arciniega, Néstor; Antepara Zambrano, Óscar; Oliva Llena, Asensio (Elsevier, 2017-08-10)
      Article
      Open Access
      This paper analyzes a low-dissipation discretization for the resolution of immiscible, incompressible multiphase flow by means of interface-capturing schemes. The discretization is built on a three-dimensional, unstructured ...
    • A negative reactivity feedback driven by induced buoyancy after a temperature transient in lead-cooled fast reactors 

      Arias Montenegro, Francisco Javier (2017-10-24)
      Article
      Open Access
      Consideration is given to the possibility to use changes in buoyancy as a negative reactivity feedback mechanism during temperature transients in heavy liquid metal fast reactors (HLMFRs). It is shown that by the proper ...
    • A New Hybrid Optimization Method, Application to a Single Objective Active Flow Control Test Case 

      Coma Company, Martí; Monshi Tousi, Navid; Pons Prats, Jordi; Bugeda Castelltort, Gabriel; Bergadà Granyó, Josep Maria (Multidisciplinary Digital Publishing Institute, 2022-04-12)
      Article
      Open Access
      Genetic Algorithms (GA) are useful optimization methods for exploration of the search space, but they usually have slowness problems to exploit and converge to the minimum. On the other hand, gradient based methods converge ...
    • A new subgrid characteristic length for turbulence simulations on anisotropic grids 

      Trias Miquel, Francesc Xavier; Gorobets, Andrei; Silvis, Maurits; Verstappen, Roel; Oliva Llena, Asensio (2017-11-29)
      Article
      Open Access
      Direct numerical simulations of the incompressible Navier-Stokes equations are not feasible yet for most practical turbulent flows. Therefore, dynamically less complex mathematical formulations are necessary for coarse-grained ...
    • A novel method to determine the discharge coefficient of constant section nozzles under compressible dynamic flow conditions 

      Comas Amengual, Ángel; Río Cano, Carlos; Bergadà Granyó, Josep Maria (2019-07)
      Article
      Restricted access - publisher's policy
      The present paper introduces a novel transient experimental method employed to determine the discharge coefficient of constant section nozzles of small diameters of 1 to 3 mm and with a length/diameter ratio of around one. ...
    • A numerical investigation of laminar flow over a backward facing inclined step 

      Mushyam, Aditya; Bergadà Granyó, Josep Maria; Nayeri, C. Navid (2016-08)
      Article
      Open Access
      The aim of the present study is to analyze the two dimensional flow over a backward-facing-inclined step in laminar flow regime. The inspiration for the present work is derived from the fact that in automobile industry, ...