Papers by Antonio Castelo
Abstract. This work presents a numerical method,for solving three-dimensional viscoelastic free s... more Abstract. This work presents a numerical method,for solving three-dimensional viscoelastic free surface flows governed by the Oldroyd-B constitutive equation. It is an extension to three dimensions of the technique introduced by Tom´ e et al., The governing equations are solved by a finite difference method on a 3D-staggered grid. Marker particles are employed,to describe the fluid providing the visualization and
Topology-Preserving lambda
TEMA - Tendências em Matemática Aplicada e Computacional, 2005
The present work is concerned with a study of numerical schemes for solving two-dimensional time-... more The present work is concerned with a study of numerical schemes for solving two-dimensional time-dependent incompressible free-surface fluid flow problems. The primitive variable flow equations are discretized by the finite difference method. A projection method is employed to uncouple the velocity components and pressure, thus allowing the solution of each variable separately (a segregated approach). The diffusive terms are discretized by Implicit Backward and Crank-Nicolson schemes, and the non-linear advection terms are approximated by the high order upwind VONOS (Variable-Order Non-oscillatory Scheme) technique. In order to improved numerical stability of the schemes, the boundary conditions for the pressure field at the free surface are treated implicitly, and for the velocity field explicitly. The numerical schemes are then applied to the simulation of the Hagen-Poiseuille flow, and container filling problems. The results show that the semi-implicit techniques eliminate the stability restriction in the original explicit GENSMAC method.
A Numerical Technique for Solving the Maxwell Model for Free Surface Flows
TEMA - Tendências em Matemática Aplicada e Computacional, 2004
ABSTRACT This work is concerned with the development of a numerical technique for solving free su... more ABSTRACT This work is concerned with the development of a numerical technique for solving free surface flows of a Maxwell fluid. The governing equations for the flow of a Maxwell type fluid together with appropriate boundary conditions are given. The free surface stress conditions are treated in details. A novel formulation for calculating the extra stress components on rigid boundaries is given. The numerical technique presented in this work employs the finite difference method on a staggered grid and employs the ideas of the MAC (Marker-and-Cell) method. Numerical results demonstrating that this numerical technique can solve viscoelastic flows governed by the Maxwell model are presented. Moreover, validation results are presented.
UM MÉTODO SEMI-IMPLÍCITO PARA RESOLVER ESCOAMENTOS IN-COMPRESSÍVEIS COM SUPERFÍCIE LIVRE
TURBULENT MHD FREE SURFACE FLOW IN SQUARE CONTAINERS
A FINITE DIFFERENCE TECHNIQUE FOR SIMULATING THREE-DIMENSIONAL NON-NEWTONIAN FREE SURFACE FLOWS
A NEW APPROACH FOR SOLVING THE OLDROYD-B MODEL FOR 3D FREE3 SURFACE FLOWS
A Finite Difference Method for Solving Unsteady Viscoelastic Free Surface Flows: Maxwell Model
A Marker-and-Cell Method for Solving Viscoelastic Free Surface Flows of a Second Order Fluid
AN ACCURATE CARTESIAN GRID METHOD FOR VISCOUS INCOMPRESSIBLE FLOWS WITH COMPLEX IMMERSED
Numerical simulation of axisymmetric nonNewtonian free surface flows
ABSTRACT We present a numerical method for solving axisymmetric transient non-Newtonian free surf... more ABSTRACT We present a numerical method for solving axisymmetric transient non-Newtonian free surface flows. The method can be considered as an extension of two-dimensional GENSMAC code, employing a marker-and-cell technique and solving the governing equations using finite difference approximations on a staggered grid. We use marker particles which provide both the location and visualization of the free surface. Several simulations demonstrating the difference between Newtonian and non-Newtonian flows are presented.
APPLICATION OF HIGH-ORDER UPWIND DISCRETIZATIONS FOR CALCULATING INCOMPRESSIBLE FLUID FLOWS
Numerical study of a gas bubble rising through stagnant fluid
Numerical Solution of Viscoelastic Free Surface Flows Using the PTT Constitutive Equation
Free-surface and two-fluid flow simulations are computationally demanding tasks. The freedom allo... more Free-surface and two-fluid flow simulations are computationally demanding tasks. The freedom allowed when using unstructured grids can be exploited to develop efficient methods for this type of problems. For instance, level-set methods and front tracking methods can be combined onto an unstructured grid method that combines advantages of both methods. In this work, methods to solve incompressible two-dimensional two-fluid flows on unstructured grids are discussed. The Navier-Stokes equations are discretized by suitable finite element methods. The numerical method for the solution is based on the projection method to uncouple the system of non-linear equations. Strategies employed for the representation of the interface between fluids are discussed. For instance, the interface can be represented by the zero level set of a function φ plus additional marker points of the computational mesh. In the standard Eulerian level-set method, this function is advected through the domain by solving a pure advection equation. To reduce mass conservation errors that can arise from this step, a Lagrangian technique, which moves the nodes of the finite element mesh, and consequently, the information stored in each node, can be employed. Due to the large distortion of the mesh that can occur, remeshing procedures are required in order to control de quality of the mesh. Results from some simulations are shown to compare the mass conservation and accuracy of the various discussed methodologies.
Exact solution of the SPTT model for fully developed channel flows
Numerical simulations using a 1D self-consistent plasma-aerosol model were compared to experiment... more Numerical simulations using a 1D self-consistent plasma-aerosol model were compared to experimental measurements of a dusty argon-silane RF plasma with corresponding operating conditions. Experimental measurements were made of the spatiotemporal profiles of the intensities of laser light scattering and plasma emission. Qualitative agreement was found for several major aspects of the evolution of the emission and scattering intensity profiles.
Upwind schemes for convection dominated problems
Surface Tension Implementation for Gensmac2d
Journal of the Brazilian Society of Mechanical Sciences, 2001
Similarly to MAC (Welch et al., 1965), SMAC (Amsden and Harlow, 1970), and GENSMAC (Tome and McKe... more Similarly to MAC (Welch et al., 1965), SMAC (Amsden and Harlow, 1970), and GENSMAC (Tome and McKee, 1994) methods, in GENSMAC2D, the equations Eqs. (3)(6) are discretized by finite differences in a staggered grid. However, in GENSMAC2D, the fluid domain is tracked ...
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Papers by Antonio Castelo