Subsonic Flow Past an Oscillating Cascade with Finite Mean Flow Deflection

AIAA Journal ◽  
1980 ◽  
Vol 18 (5) ◽  
pp. 540-548 ◽  
Author(s):  
Joseph M. Verdon ◽  
Joseph R. Caspar
Keyword(s):  
Subsonic Flow ◽  
Mean Flow ◽  
Flow Past ◽  
Flow Deflection

Influence of camber on sound generation by airfoils interacting with high-frequency gusts

1997 ◽  
Vol 353 ◽  
pp. 221-259 ◽  
Author(s):  
MATTHEW R. MYERS ◽  
E. J. KERSCHEN
Keyword(s):  
Flat Plate ◽  
High Frequency ◽  
Incidence Angle ◽  
Outer Region ◽  
Asymptotic Region ◽  
Mean Flow ◽  
Previous Theory ◽  
Airfoil Surface ◽  
Curvature Effects ◽  
Flow Past

A theoretical model is developed for the sound generated when a convected disturbance encounters a cambered airfoil at non-zero angle of attack. The model is a generalization of a previous theory for a flat-plate airfoil, and is based on a linearization of the Euler equations about the steady, subsonic flow past the airfoil. High-frequency gusts, whose wavelengths are short compared to the airfoil chord, are considered. The airfoil camber and incidence angle are restricted so that the mean flow past the airfoil is a small perturbation to a uniform flow. The singular perturbation analysis retains the asymptotic regions present in the case of a flat-plate airfoil: local regions, which scale on the gust wavelength, at the airfoil leading and trailing edges; a ‘transition’ region behind the airfoil which is similar to the transition zone between illuminated and shadow regions in optical problems; and an outer region, far away from the airfoil edges and wake, in which the solution has a geometric-acoustics form. For the cambered airfoil, an additional asymptotic region in the form of an acoustic boundary layer adjacent to the airfoil surface is required in order to account for surface curvature effects. Parametric calculations are presented which illustrate that, like incidence angle, moderate amounts of airfoil camber can significantly affect the sound field produced by airfoil–gust interactions. Most importantly, the amount of radiated sound power is found to correlate very well with a single aerodynamic loading parameter, αeff, which is an effective mean-flow incidence angle for the airfoil leading edge.

Subsonic Turbulent Flow Past a Planar Fence

1979 ◽  
Vol 101 (3) ◽  
pp. 373-375
Author(s):  
M. L. Agarwal ◽  
P. K. Pande ◽  
Rajendra Prakash
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Field ◽  
Boundary Conditions ◽  
Mean Flow ◽  
Governing Equations ◽  
Flow Past ◽  
Entire Flow ◽  
The Mean ◽  
Shape And Size

The mean flow past a fence submerged in a turbulent boundary layer is numerically simulated. The governing equations have been simplified by neglecting the convective effects of turbulence and solved numerically using experimental boundary conditions. The information obtained includes the shape and size of the upstream and downstream separation bubbles and the streamline pattern in the entire flow field. General agreement between the simulated and the experimental flow field was found.

Numerical Simulation on Mean Flow past a Circular Cylinder Based on the Lattice Boltzmann Method

2011 ◽  
Vol 105-107 ◽  
pp. 2307-2310
Author(s):  
Jian Ping Yu ◽  
Shu Rong Yu ◽  
Xing Wang Liu
Keyword(s):  
Circular Cylinder ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Mean Flow ◽  
Experiment Data ◽  
Data Simulation ◽  
Lattice Boltzmann Methods ◽  
Flow Past ◽  
Computational Fluid Dynamics Cfd ◽  
Boltzmann Method

Lattice Boltzmann methods (LBM) have become an alternative to conventional computational fluid dynamics (CFD) methods for various systems. In this paper, flow field of mean flow past a circular cylinder was simulated based on the lattice Boltzmann method. The streamline of air past the cylinder illuminated that the fluid adhere on the boundary and doesn’t separate from the surface of cylinder when Re number less than 5. When Re number equal 40, flow separated to form a pair of recirculating eddies can be observed. With the Re number increasing, the trailing vortex length is growth accordingly. When Re number come up to 80, the trailing vortex begin to shed regularly. This result is consistent with the experiment data. Drag coefficient that fluid act on the surface of cylinder was calculated. The calculated results were same as the experiment data. Simulation indicate that LBM can simulate the vortex taking place and shedding effectively.

Partially Averaged Navier–Stokes (PANS) Method for Turbulence Simulations: Flow Past a Circular Cylinder

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Sunil Lakshmipathy ◽  
Sharath S. Girimaji
Keyword(s):  
Circular Cylinder ◽  
Navier Stokes ◽  
Length Scale ◽  
Detached Eddy Simulation ◽  
Mean Flow ◽  
Closure Model ◽  
Variable Resolution ◽  
Eddy Simulation ◽  
Flow Past ◽  
High Reynolds

The objective of this study is to evaluate the capability of the partially averaged Navier–Stokes (PANS) method in a moderately high Reynolds number (ReD 1.4×105) turbulent flow past a circular cylinder. PANS is a bridging closure model purported for use at any level of resolution ranging from Reynolds-averaged Navier–Stokes to direct numerical simulations. The closure model is sensitive to the length-scale cut-off via the ratios of unresolved-to-total kinetic energy (fk) and unresolved-to-total dissipation (fε). Several simulations are performed to study the effect of the cut-off length-scale on computed closure model results. The results from various resolutions are compared against experimental data, large eddy simulation, and detached eddy simulation solutions. The quantities examined include coefficient of drag (Cd), Strouhal number (St), and coefficient of pressure distribution (Cp) along with the mean flow statistics and flow structures. Based on the computed results for flow past circular cylinder presented in this paper and analytical attributes of the closure model, it is reasonable to conclude that the PANS bridging method is a theoretically sound and computationally viable variable resolution approach for practical flow computations.

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