Aeroacoustic simulation of flexible structures in low Mach number turbulent flows

2021 ◽  
pp. 105020
Author(s):  
Elena Kolb ◽  
Michael Schäfer
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
Flexible Structures ◽  
Low Mach Number ◽  
Aeroacoustic Simulation

A low-dissipation DG method for the under-resolved simulation of low Mach number turbulent flows

2019 ◽  
Vol 77 (6) ◽  
pp. 1739-1755 ◽  
Author(s):  
A. Nigro ◽  
C. De Bartolo ◽  
A. Crivellini ◽  
M. Franciolini ◽  
A. Colombo ◽  
...  
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
Low Mach Number ◽  
Low Dissipation ◽  
Dg Method

The generation of combustion noise by chemical inhomogeneities in steady, low-Mach-number duct flows

1980 ◽  
Vol 99 (2) ◽  
pp. 383-397 ◽  
Author(s):  
Y. L. Sinai
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Turbulent Flows ◽  
Low Frequency ◽  
Combustion Noise ◽  
Low Mach Number ◽  
First Order ◽  
Specific Heats ◽  
Chemically Reacting ◽  
Frequency Character

The low-frequency character of two model problems is exploited in order to illustrate the acoustic consequences of the interactions between chemically reacting (or relaxing) inhomogeneities and flames or constrictions in ducts. The monopole of the former is associated with heat transfer in a fluid which exhibits variations in its specific heats, while in the latter there is an extension of the classical phenomenon associated with the pulsations of an inhomogeneity of the fluid compressibility. This second mechanism is found to be insignificant, but the heat-conduction source is considered to be very powerful at sufficiently low Mach numbers; in fact, to first order it is independent of the flow Mach number for laminar, as well as a certain class of turbulent, flows.

A Time-Accurate Projection Method for Low-Mach Number Variable Density Flows in Curvilinear Grids

2009 ◽  
Author(s):  
F. N. Fard ◽  
B. Lessani
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
Projection Method ◽  
Time Integration ◽  
Variable Density ◽  
Integration Scheme ◽  
Coordinate Systems ◽  
Low Mach Number ◽  
Curvilinear Coordinate ◽  
Time Integration Scheme

A time-accurate numerical algorithm is proposed for low Mach number variable density flows in curvilinear coordinate systems. In order to increase the stability of the method, a predictor-corrector time integration scheme, coupled with the projection method, is employed. The projection method results in a constant-coefficient Poisson equation for the pressure in both the predictor and corrector steps. The continuity equation is fully satisfied at each step. To prevent the pressure odd-even decoupling typically encountered in collocated grids, a flux interpolation technique is developed. The spatial discretization method offers computational simplicity and straightforward extension to 3D curvilinear coordinate systems, which are essential in the simulation of turbulent flows in complex geometries. The accuracy and stability of the algorithm are tested with a series of numerical experiments, and the results are validated against the available data in the literature.

Validation of CE/SE Scheme in Low Mach Number Direct Aeroacoustic Simulation

2014 ◽  
Vol 15 (2) ◽  
Author(s):  
Garret C. Y. Lam ◽  
Randolph C. K. Leung ◽  
K. H. Seid ◽  
S. K. Tang
Keyword(s):  
Mach Number ◽  
Low Mach Number ◽  
Aeroacoustic Simulation

Artificial Compressibility Method and Preconditioning Method for Solving Two Dimensional Incompressibile Flow

2011 ◽  
Author(s):  
Hyungro Lee ◽  
Einkeun Kwak ◽  
Seungsoo Lee
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Low Mach Number ◽  
Artificial Compressibility ◽  
Artificial Compressibility Method ◽  
Preconditioning Method

In this study, two commonly used numerical methods for the analysis of incompressible flows (or low Mach number flows), Chorins’ artificial compressibility method and Wiess and Smith’s preconditioning method are compared. Also, the convergence characteristics of two methods are numerically investigated for two-dimensional laminar and turbulent flows. Although the two methods have similar governing equations, the eigensystems and other details are very different. The eigensystems of the artificial compressibility method and the preconditioning method are analytically examined. An artificial compressibility code that solves the incompressible RANS (Reynolds Averaged Navier-Stokes) equations is newly developed for the study. An artificial compressibility code and a well-verified existing low Mach number code uses Roe’s approximate Riemann solver in conjunction with a cell centered finite volume method. Using MUSCL extrapolation with nonlinear limiters, 2nd order spatial accuracy is achieved while maintaining TVD (total variation diminishing) property. AF-ADI (approximate factorization-alternate direction implicit) method is used to get the steady solution for both codes. Menter’s k–ω SST turbulence model is used for the analysis of turbulent flows. Navier-Stokes equations and the turbulence model equations are solved in a loosely coupled manner.

LES and DNS of Turbulent Flows in Weakly Compressible Condition

2007 ◽  
Author(s):  
Takeo Kajishima ◽  
Takashi Ohta
Keyword(s):  
Mach Number ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Plane Channel ◽  
Scale Model ◽  
Turbulent Shear ◽  
Quadrant Analysis ◽  
Number Range ◽  
Low Mach Number ◽  
Flow Scheme

Flow field of low Mach number (e.g. M <0.3) is usually simulated by the incompressible flow scheme due to the severe limitation of time-increment in the compressible flow scheme. In this work, we propose a modification to the usual incompressible scheme, based on the elliptic equation for pressure, to improve the accuracy for turbulent flows considering weak compressibility. Two examples will be shown to validate our method. (1) LES (Large-Eddy Simulation) was conducted for turbulent flow around NACA0012 airfoil. Particular attention was focused on the influence of compressibility, despite the low Mach number range. In addition, new subgrid scale model of one-equation type using dynamic procedure was compared with traditional Smagorinsky model. Our method successfully reproduced the separation bubble near the leading edge, resulted in the improvement in the intensity of pressure fluctuation. (2) DNS (Direct Numerical Simulation) of turbulent flow in a plane channel is carried out, taking wall temperature difference into account. As a result of the density fluctuation in near-wall eddies, asymmetric profiles are observed in turbulence statistics. By the 4-quadrant analysis of turbulent shear stress, it is found that the ejection events in the vicinity of the walls are particularly affected by the density variation.

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