Solution numérique des équations compressibles de Navier-Stokes

Les équations de base -- Résolution numérique des équations -- Résultats numériques

A Numerical study of turbulent flow using a nonstaggered mesh

Transport equations -- Numerical discretization -- Boundary

Résolution numérique des écoulements tridimensionnels turbulents

Les équations de base -- Les équations de mouvement -- Les modèles de turbulence -- Les équations à résoudre -- Génération du maillage -- Transformation des équations -- Élaboration du schéma numérique -- Stockage et discrétisation spatiale -- Discrétisation en temps et calcul de la pression -- Algorithme de résolution -- Conditions aux frontières -- Résultars numériques -- Cas bidimensionnels -- Cas tridimensionnels

Modelling Complex Draft-Tube Flows using Near-Wall Turbulence Closures

This paper presents a finite-volume method for simulating flows through complex hydroturbine draft-tube configurations using near-wall turbulence closures. The method employs the artificial-compressibility pressure-velocity coupling approach in conjunction with multigrid acceleration for fast convergence on very fine grids. Calculations are carried out for a draft tube with two downstream piers on a computational mesh consisting of 1.2x10{sup 6} nodes. Comparisons of the computed results with measurements demonstrate the ability of the method to capture most experimental trends with reasonable accuracy. Calculated three-dimensional particle traces reveal very complex flow features in the vicinity of the piers, including horse-shoe longitudinal vortices and and regions of flow reversal

Flow behavior analysis of confined fluid in a flexible tube: application of asymptotic approach

In this paper, we asymptotically investigate a confined fluid flow in a flexible tube with a variable section. The fluid is considered to be newtonian, incompressible and it elapses in elastic and isotropic shell. This study provides a review of recent analysing the effects of the elastic wall tube properties over the fluid behaviour. The unsteady fluid flow will be analysed following the singular perturbations theory according to a large Reynolds number and a small aspect radio. The wall is assumed to be a thin shell that generate a small axisymmetric vibration. This model is mathematically developed by using the thin shell linear theory that is governed by a geodesic curvature parameter

Analytical modelling for Newtonian fluid flow through an elastic tube

The objective of the present work is to develop analytical modelling of an unsteady fluid flow through an elastic tube. The fluid is considered to be Newtonian and incompressible. The cylindrical tube wall boundaries are isotropic. The study provides a review of recent modelling aimed at understanding the effects of fluid parameters over the elastic tube wall behaviour. First of all, the fluid flow is analysed following an asymptotic approach according to a large Reynolds number and a small aspect radio. Second of all, the wall has been assumed to be a thin shell, which generates a small axisymmetric vibration. The mathematical model is developed according the thin shell theory. The dynamic behaviour of the tube wall is represented and discussed

Reducing drag on a flat plate subjected to incompressible laminar flow

The idea behind this work comes from the question: What is the impact of plate corrugations on drag? In this context, a numerical study of laminar incompressible flow over a flat plate and over corrugated plates is carried out. Numerical analysis is performed for low Reynolds numbers (Re= 10, Re = 50, Re = 100, Re = 500, Re =1000) using the computational fluid dynamics (CFD) software ANSYS FLUENT. Simulations results are compared to each others and with those of the reference plate (flat plate (figure 4a)). Comparisons are made via drag coefficient Cd. This work is the beginning of a study that evaluates the impact of corrugations on drag reduction on a flat plate

Étude numérique des écoulements turbulents dans les cascades

Les équations fondamentales -- Les modèles mathématiques de turbulence -- Transformation des équations en coordonnées -- Résolution numérique

Analytical modelling for Newtonian fluid flow through an elastic tube

The objective of the present work is to develop analytical modelling of an unsteady fluid flow through an elastic tube. The fluid is considered to be Newtonian and incompressible. The cylindrical tube wall boundaries are isotropic. The study provides a review of recent modelling aimed at understanding the effects of fluid parameters over the elastic tube wall behaviour. First of all, the fluid flow is analysed following an asymptotic approach according to a large Reynolds number and a small aspect radio. Second of all, the wall has been assumed to be a thin shell, which generates a small axisymmetric vibration. The mathematical model is developed according the thin shell theory. The dynamic behaviour of the tube wall is represented and discussed