A vertex centered high order MUSCL scheme applying to linearised Euler acoustics

This report proposes a linearised Euler discretisation that will be compatibl- e with some existing state of art in numerical methods for compressible flows on unstructured triangulations. The important property is the use of a stabilisation terms involving sixth-order derivatives. The main idea is to realize this programme by developing a scheme that enjoys superconvergence, i.e. a high convergence order when it is applied to a cartesian triangulation. We present a test case validating the theoretical order of accuracy and the so-called Tam test case, allowing some comparisons with two other typical numerical schemes for acoustics

Numerical Boundary Conditions for Schemes with Centered and Biased Differences in Subsonic Gas Dynamics

For finite-difference schemes of EBR class in multi-dimensional inviscid gas dynamics, the nonreflecting boundary conditions are analyzed and developed. The wave-reflection properties of discrete models differ significantly from each other and from the continuous Euler equations. For certain schemes there exist local boundary conditions which lead to small reflections of waves with arbitrary incidence angle. Numerical examples are shown both linear and nonlinear

The Behavior of Two Near-Wall Models for k-\varepsilon Prediction of Stall

This study compares the application of several variants of the k - \varepsil- on model for the prediction of a stall around a two-body NLR airfoil. A Chen-Patel two-layer model and a Reichardt wall law ær combined or not with the Menter correction. The Reichardt wall-law does not give a good prediction of the stall, either with or without the Menter correction, although this second option is more accurate for non-detached flows. The stall is not predicted either by the original Chen-Patel two-layer model but well predicted if the Menter correction is added

On time averaging in Organised Eddy Simulation Modelling

A new technique for devising new models of turbulent viscosity for unsteady quasi-periodic flows is proposed in the report. The turbulent flow simulation strategy is based on two different flowfield decompositions, the Reynolds averaging, and the phase averaging. Properties of the mean flow are recovered on the base of the time-averaging of quasi-periodic solution of the Reynolds averaged Navier-Stokes equations. This yields an upper bound for the turbulent viscosity of the Organised Eddy Simulation model. The methods under study are verified on a typical test case, the flow around a square cylinder

Characteristic-Based Volume Penalization Method for Compressible Flow Simulations on Unstructured Meshes

The Characteristic-Based Volume Penalization (CBVP) method for numerical simulations of compressible flow over solid obstacles on unstructured meshes is presented. The approach belongs to the class of immersed boundary methods and is not relying on body-fitted meshes. Characteristic penalization terms, added to the compressible Navier-Stokes equations, are used to impose Dirichlet and Neumann boundary conditions on solid-fluid interface with an a priori defined accuracy. The details of numerical implementation, utilizing hybrid finitevolume method with high order edge-based reconstruction schemes in the flow region and loworder finite-difference approximation inside of the obstacle, are discussed. The developed algorithm provides the ability to perform calculations on grids of arbitrary type, including fully unstructured meshes. The efficiency of the characteristic based volume penalization method and its numerical implementation is demonstrated for shock wave reflection, acoustic pulse reflection and Couette flow problems. The results of CBVP simulations are compared with the numerical solutions of the same problems using Brinkman volume penalization method

Unstable and Unsteady Aerodynamics : Compared Information from Different Numerical Models

We review a few recent investigations concerning LES (Large Eddy Simulation), OES (Organised Eddy Simulation), and Statistical Modelling works with two-equation RANS models aiming at preparing short term improvement of industrial tools for a good representation of separated, unsteady flows, involving vortex shedding. A focus will be proposed on OES modelling and on the use of wall laws. Examples will concern vortex shedding behind cylinders and airfoils, dynamic stall of multi-body airfoil. This paper is dedicated to Pierre Perrier at the occasion of the NFD2000 symposium organised in his honour

The behavior of two near-wall models for K - #epsilon# prediction of stall

Theme 4 - Simulation et optimisation de systemes complexes - Projet SinusSIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.2000 n.4075 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

On time averaging in organised eddy simulation modelling

Theme 4 - Simulation et optimisation de systemes complexes - Projet SinusSIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.2000 n.4040 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

The behavior of two near-wall models for K - #epsilon# prediction of stall

Theme 4 - Simulation et optimisation de systemes complexes - Projet SinusSIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.2000 n.4075 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc