Navier-Stokes Computations of Cavity Aeroacoustics with Suppression Devices

1994 ◽  
Vol 116 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Oktay Baysal ◽  
Guan-Wei Yen ◽  
Kamran Fouladi
Keyword(s):  
Turbulent Flows ◽  
Cavity Length ◽  
Stokes Equations ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Flow Properties ◽  
Navier Stokes Equations ◽  
Time Series Analyses ◽  
Cavity Acoustics ◽  
Volume Method

Effectiveness of two devices to suppress the cavity acoustics was computationally investigated. Two dimensional, computational simulations were performed for the transonic, turbulent flows past a cavity, which was first equipped with a rear face ramp and then with a spoiler. The Reynolds-averaged, unsteady, compressible, full Navier-Stokes equations were solved time accurately by a second-order accurate, implicit, upwind, finite-volume method. The effect of turbulence was included through the Baldwin-Lomax model with modifications for the multiple-wall effects and for the highly vortical flow with a shear layer. The results included instantaneous and time-averaged flow properties, and time-series analyses of the pressure inside the cavity, which compared favorably with the available experimental data. These results were also contrasted with the computed aeroacoustics of the same cavity (length-to-depth ratio of 4.5), but without a device, to demonstrate the suppression effectiveness.

Turbulent Flow in Two-Inlet Channels

1993 ◽  
Vol 115 (4) ◽  
pp. 638-645 ◽  
Author(s):  
Hsiao C. Kao
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Flow Properties ◽  
Navier Stokes Equations ◽  
High Reynolds ◽  
Inflow Conditions ◽  
Number Form

The problem of turbulent flows in two-inlet channels has been studied numerically by solving the Reynolds-averaged Navier-Stokes equations with the k–ε model in a mapped domain. Both the high Reynolds number and the low Reynolds number form were used for this purpose. In general, the former predicts a weaker and smaller recirculation zone than the latter. Comparisons with experimental data, when applicable, were also made. The bulk of the present computations used, however, the high Reynolds number form to correlate different geometries and inflow conditions with the flow properties after turning.

scholarly journals The effort of increasing Reynolds number in POD-Galerkin Reduced Order Methods: from laminar to turbulent flows

2018 ◽  
Author(s):  
Shafqat Ali ◽  
Saddam Hijazi ◽  
Sokratia Georgaka ◽  
Francesco Ballarin ◽  
Giovanni Stabile ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Finite Element ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Reduced Order ◽  
Volume Method ◽  
Reduced Order Methods

We present different strategies to be able to increase Reynolds number in Reduced Order Methods (ROMs), from laminar to turbulent flows, in the context of the incompressible parametrised Navier-Stokes equations. The proposed methodologies are based on different full order discretisation techniques: the finite element method and the finite volume method. For what concerns finite element full order discretisations which in this work aim to be used from low to moderate Reynolds numbers the

scholarly journals Navier-Stokes Calculations of Transonic Flows Past Cavities

1991 ◽  
Vol 113 (3) ◽  
pp. 368-376 ◽  
Author(s):  
S. Srinivasan ◽  
O. Baysal
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Reynolds Stresses ◽  
Computational Investigation ◽  
Flow Properties ◽  
Navier Stokes Equations ◽  
Transonic Flows ◽  
Instantaneous Pressure ◽  
Time Series Analyses

Presented in this paper is a computational investigation of subsonic and transonic flows past three-dimensional deep and transitional cavities. Simulations of these self-induced oscillatory flows have been generated through time-accurate solutions of the Reynolds averaged, full Navier-Stokes equations, using the explicit MacCormack scheme. The Reynolds stresses have been included through the Baldwin-Lomax algebraic turbulence model with certain modifications. The computational results include instantaneous and time averaged flow properties. The results of an experimental investigation have been used not only to validate the time-averaged results, but also to investigate the effects of varying the Mach number and the incoming boundary-layer thickness. Time series analyses have been performed for the instantaneous pressure values on the cavity floor and compared with the results obtained by a predictive formula. While most of the comparisons have been favorable, some discrepancies have been observed, particularly on the rear face. The present results help understanding the three-dimensional and unsteady features of the separations, vortices, the shear layer, as well as some of the aeroacoustic phenomena of compressible cavity flows.

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure

2010 ◽  
Vol 297-301 ◽  
pp. 924-929
Author(s):  
Inès Bhouri Baouab ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Wind Flow ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Twin Buildings ◽  
Volume Method ◽  
Numerical Examination

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.

Numerical Investigation of Flow Around Bluff Bodies

1998 ◽  
Vol 14 (3) ◽  
pp. 153-159 ◽  
Author(s):  
Chou-Jiu Tsai ◽  
Ger-Jyh Chen
Keyword(s):  
Vortex Shedding ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Bluff Bodies ◽  
Near Wake ◽  
Navier Stokes Equations ◽  
Physical Description ◽  
Geometrical Shapes ◽  
Flow Phenomena ◽  
Volume Method

ABSTRACTIn this study, fluid flow around bluff bodies are studied to examine the vortex shedding phenomenon in conjuction with the geometrical shapes of these vortex shedders. These flow phenomena are numerically simulated. A finite volume method is employed to solve the incompressible two-dimensional Navier-Stokes equations. Thus, quantitative descriptions of the vortex shedding phenomenon in the near wake were made, which lead to a detailed description of the vortex shedding mechanism. Streamline contours, figures of lift coefficent, and figures of drag coefficent in various time, are presented, respectively, for a physical description.

On Direct Numerical Simulation of Turbulent Flows

2011 ◽  
Vol 64 (2) ◽  
Author(s):  
Giancarlo Alfonsi
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
High Performance Computing ◽  
Turbulent Flows ◽  
High Performance ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Turbulent Shear ◽  
Navier Stokes Equations ◽  
Performance Computing

The direct numerical simulation of turbulence (DNS) has become a method of outmost importance for the investigation of turbulence physics, and its relevance is constantly growing due to the increasing popularity of high-performance-computing techniques. In the present work, the DNS approach is discussed mainly with regard to turbulent shear flows of incompressible fluids with constant properties. A body of literature is reviewed, dealing with the numerical integration of the Navier-Stokes equations, results obtained from the simulations, and appropriate use of the numerical databases for a better understanding of turbulence physics. Overall, it appears that high-performance computing is the only way to advance in turbulence research through the front of the direct numerical simulation.

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