Multidimensional Measurements of Turbulent Boundary Layer Including Scattered Particles Using PIV Technique

2015 ◽  
Author(s):  
Yoshiki Sugawara ◽  
Takahiro Tsukahara ◽  
Yasuo Kawaguchi
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Gas Flow ◽  
Solid Particles ◽  
Gas Flows ◽  
Stress Distributions ◽  
Dominant Term ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Experimental Researches

Although many experimental researches on solid-gas flows have been conducted, the involved stress balance problem has not been elucidated. To have a deep investigation of the stress balance in gas flow with entrained solid particles, this study conducts particle image velocimetry (PIV) experiment on a horizontal turbulent boundary layer. In the experiment, air and micro-scale glass beads are chosen as the gas phase and solid particles, respectively. The velocities of both air and solid particles are obtained simultaneously based on the acquired images and by image processing; each term of the stress balance equation is calculated and the influences of solid particles are analyzed. Based on the experiment results, the dominant term of the stress in the solid-gas flow as well as the influence of the solid particles on the stress distributions are identified.

scholarly journals Effect of turbulence on the wake of a wall-mounted cube

2016 ◽  
Vol 804 ◽  
pp. 513-530 ◽  
Author(s):  
R. Jason Hearst ◽  
Guillaume Gomit ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Reattachment Length ◽  
Free Stream Turbulence ◽  
Boundary Layer Development ◽  
Image Velocimetry ◽  
Shedding Frequency ◽  
Layer Development

The influence of turbulence on the flow around a wall-mounted cube immersed in a turbulent boundary layer is investigated experimentally with particle image velocimetry and hot-wire anemometry. Free-stream turbulence is used to generate turbulent boundary layer profiles where the normalised shear at the cube height is fixed, but the turbulence intensity at the cube height is adjustable. The free-stream turbulence is generated with an active grid and the turbulent boundary layer is formed on an artificial floor in a wind tunnel. The boundary layer development Reynolds number ($Re_{x}$) and the ratio of the cube height ($h$) to the boundary layer thickness ($\unicode[STIX]{x1D6FF}$) are held constant at $Re_{x}=1.8\times 10^{6}$ and $h/\unicode[STIX]{x1D6FF}=0.47$. It is demonstrated that the stagnation point on the upstream side of the cube and the reattachment length in the wake of the cube are independent of the incoming profile for the conditions investigated here. In contrast, the wake length monotonically decreases for increasing turbulence intensity but fixed normalised shear – both quantities measured at the cube height. The wake shortening is a result of heightened turbulence levels promoting wake recovery from high local velocities and the reduction in strength of a dominant shedding frequency.

scholarly journals Statistical Parameters of the Air Turbulent Boundary Layer over Steep Water Waves Measured by the PIV Technique

2011 ◽  
Vol 41 (8) ◽  
pp. 1421-1454 ◽  
Author(s):  
Yu. Troitskaya ◽  
D. Sergeev ◽  
O. Ermakova ◽  
G. Balandina
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Interaction Parameter ◽  
Water Waves ◽  
Water Surface ◽  
Wind Wave ◽  
Wave Interaction ◽  
Statistical Parameters ◽  
Piv Technique ◽  
Wave Induced

Abstract A turbulent airflow with a centerline velocity of 4 m s−1 above 2.5-Hz mechanically generated gravity waves of different amplitudes has been studied in experiments using the particle image velocimetry (PIV) technique. Direct measurements of the instantaneous flow velocity fields above a curvilinear interface demonstrating flow separation are presented. Because the airflow above the wavy water surface is turbulent and nonstationary, the individual vector fields are conditionally averaged sampled on the phase of the water elevation. The flow patterns of the phase-averaged fields are relatively smooth. Because the averaged flow does not show any strongly nonlinear effects, the quasi-linear approximation can be used. The parameters obtained by the flow averaging are compared with the theoretical results obtained within the theoretical quasi-linear model of a turbulent boundary layer above the wavy water surface. The wave-induced pressure disturbances in the airflow are calculated using the retrieved statistical ensemble of wind flow velocities. The energy flux from the wind to waves and the wind–wave interaction parameter are estimated using the obtained wave-induced pressure disturbances. The estimated values of the wind–wave interaction parameter are in a good agreement with the theory.

Large-eddy Simulation of the Dispersion of Solid Particles in a Turbulent Boundary Layer

2006 ◽  
Vol 121 (2) ◽  
pp. 283-311 ◽  
Author(s):  
Ivana Vinkovic ◽  
Cesar Aguirre ◽  
Michel Ayrault ◽  
Serge Simoëns
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Large Eddy Simulation ◽  
Solid Particles ◽  
Eddy Simulation ◽  
Large Eddy

Dual-plane PIV technique to determine the complete velocity gradient tensor in a turbulent boundary layer

2005 ◽  
Vol 39 (2) ◽  
pp. 222-231 ◽  
Author(s):  
Bharathram Ganapathisubramani ◽  
Ellen K. Longmire ◽  
Ivan Marusic ◽  
Stamatios Pothos
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Velocity Gradient ◽  
Gradient Tensor ◽  
Velocity Gradient Tensor ◽  
Dual Plane ◽  
Piv Technique

Particle image velocimetry investigation of a turbulent boundary layer manipulated by spanwise wall oscillations

2002 ◽  
Vol 467 ◽  
pp. 41-56 ◽  
Author(s):  
GAETANO MARIA DI CICCA ◽  
GAETANO IUSO ◽  
PIER GIORGIO SPAZZINI ◽  
MICHELE ONORATO
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Turbulent Boundary Layer ◽  
Particle Image ◽  
Oscillation Amplitude ◽  
Research Programme ◽  
Oscillation Period ◽  
Wall Turbulence ◽  
Image Velocimetry ◽  
Near Wall

Particle image velocimetry has been applied to the study of a canonical turbulent boundary layer and to a turbulent boundary layer forced by transversal wall oscillations. This work is part of the research programme at the Politecnico di Torino aerodynamic laboratory with the objective of investigating the response of near-wall turbulence to external perturbations. Results are presented for the optimum oscillation period of 100 viscous time units and for an oscillation amplitude of 320 viscous units. As expected, turbulent velocity fluctuations are considerably reduced by the wall oscillations. Particle image velocimetry has allowed comparisons between the canonical and forced flows in an attempt to find the physical mechanisms by which the wall oscillation influences the near-wall organized motions.

Conical gas flows with shock waves and turbulent boundary layer separation

2012 ◽  
Vol 47 (2) ◽  
pp. 263-280 ◽  
Author(s):  
M. A. Zubin ◽  
N. A. Ostapenko ◽  
A. A. Chulkov
Keyword(s):  
Boundary Layer ◽  
Shock Waves ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Separation ◽  
Gas Flows ◽  
Layer Separation
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