Search results for "numerical [Methods]"
showing 10 items of 500 documents
A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy
2021
AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a…
A novel One Domain Approach for free fluid-porous medium transport simulation. Preliminary results
2022
We present a new numerical solver for free-fluid flowing over and inside a porous medium. It is based over a macroscopic approach and one fictitious medium is assumed inside the domain, according to the One Domain Approach. Preliminary results are shown and compared with the ones provided by the well-known DuMux solver which applies a two Domain Approach.
Tools for studying water vapor at high temperatures
2014
1. Kinetics and Oxidation Mechanisms 1.1 Experimental Devices that Produce Water Vapor1.2 Using the Jump Method to Understand Oxidation Mechanisms and Kinetics1.3 Detection of Breakaway Oxidation with Acoustic Emission during Thermal Oxide Scale Growth 1.4 Stress Analysis during and after Oxidation 2. Characterization 2.1 Use and Potential of Environmental SEM (ESEM) in High-Temperature Oxidation and Corrosion Studies in Wet Air 2.2 In Situ X-Ray Diffraction for Water Vapor Analyses2.3 Use of Synchrotron Beam for Evaluating the Influence of Water Vapor on the Corrosion of Metallic Materials 2.4 Raman Spectrometry2.5 In Situ Steam Oxidation Chamber Coupled to XPS 2.6 Hydrogen Profiling in Ox…
Direct numerical simulations of creeping to early turbulent flow in unbaffled and baffled stirred tanks
2018
Abstract It has been known for a long time that the fluid flow and several global quantities, such as the power and pumping numbers, are about the same in baffled and unbaffled mechanically stirred vessels at low Reynolds numbers, but bifurcate at some intermediate Re and take drastically different values in fully turbulent flow. However, several details are not yet completely understood, notably concerning the relation of this bifurcation with the flow features and the transition to turbulence. In order to shed light on these issues, computational fluid dynamics was employed to predict the flow field in two vessels stirred by a six-bladed Rushton turbine at Reynolds numbers from 0.2 to 600…
Smoothed particles hydrodynamics numerical simulations of droplets walking on viscous vibrating liquid
2016
We study the phenomenon of the "walking droplet", by means of numerical fluid dynamics simulations using the Smoothed Particle Hydrodynamics numerical method. This phenomenon occurs when a millimetric drop is released on the surface of an oil of the same composition, contained in a tank and subjected to vertical oscillations of frequency and amplitude very close to the Faraday instability threshold. At appropriate values of the parameters of the system under study, the oil droplet jumps permanently on the surface of the vibrating liquid forming a localized wave-particle system, reminding the behaviour of a wave particle quantum system as suggested by de Broglie. In our study, we made releva…
The impacts of the ALE and hydrostatic-pressure approaches on the energy budget of unsteady free-surface flows
2008
Abstract This paper focuses on the energy budget in the calculation of unsteady free-surface flows on moving grids with and without using the ‘arbitrary Lagrangian–Eulerian’ (ALE) formulation or hydrostatic-pressure assumption. The numerical tool is an in-house general-purpose solver for the unsteady, incompressible and homogeneous Navier–Stokes equations in a Cartesian domain. An explicit fractional-step method and co-located finite-volume method are used for the second-order accurate integrations in time and space. The test cases are nonlinear and linear irrotational standing waves, which allow to characterise the impacts of an ALE or Eulerian formulation with moving grids by comparison w…
MAST-RT0 solution of the incompressible Navier–Stokes equations in 3D complex domains
2020
A new numerical methodology to solve the 3D Navier-Stokes equations for incompressible fluids within complex boundaries and unstructured body-fitted tetrahedral mesh is presented and validated with three literature and one real-case tests. We apply a fractional time step procedure where a predictor and a corrector problem are sequentially solved. The predictor step is solved applying the MAST (Marching in Space and Time) procedure, which explicitly handles the non-linear terms in the momentum equations, allowing numerical stability for Courant number greater than one. Correction steps are solved by a Mixed Hybrid Finite Elements discretization that assumes positive distances among tetrahedr…
Inverse Problems Light: Numerical Differentiation
2001
(2001). Inverse Problems Light: Numerical Differentiation. The American Mathematical Monthly: Vol. 108, No. 6, pp. 512-521.
Some Improvements on Relativistic Positioning Systems
2018
[EN] We make some considerations about Relativistic Positioning Systems (RPS). Four satellites are needed to position a user. First of all we define the main concepts. Errors should be taken into account. Errors depend on the Jacobian transformation matrix. Its Jacobian is proportional to the tetrahedron volume whose vertexes are the four tips of the receiver-satellite unit vectors. If the four satellites are seen by the user on a circumference in the sky, then, the Jacobian and the tetrahedron volume vanish. The users we consider are spacecraft. Spacecraft to be positioned cannot be close to a null Jacobian satellites-user configuration. These regions have to be avoided choosing an appropr…