Measuring turbulence energy with PIV in a backward-facing step flow

Piirto, M.; Saarenrinne, Pentti; Eloranta, H.; Karvinen, R.

doi:10.1007/s00348-003-0607-z

Cited by 41 publications

(30 citation statements)

References 24 publications

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“…Since the estimated values of e are the largest (and g is the smallest) across the channel, the values of l y /g reported in Table 1 are the maximum. Table 1 shows that 2:9 6 l þ y 6 52:4 compared to 6:7 6 l þ z 6 43:6 reported by Johnson and Barlow [8] while 2 6 l y /g 6 23 compared to 8 6 l y /g 6 32 reported by Piirto et al [1] and 4.6 6 l z /g 6 29.7 by Johnson and Barlow [8]. In general, values of l þ y and l y /g are smallest for Test SM1 and largest for Test RIB.…”

Section: Interrogation Area (Ia) Sizesmentioning

confidence: 59%

“…Particle image velocimetry (PIV), on the other hand, is a whole-field non-intrusive velocity measurement technique, and can overcome some of the limitations inherent to the LDA and hot-wires. For example, the stereo PIV has been used in recent studies to measure the terms in the transport equation of the turbulent kinetic energy (Piirto et al [1]) while Ganapathisubramani et al [2] used the dual plane PIV to evaluate the complete velocity gradient tensor and the complete vorticity vector in a turbulent boundary layer. The fundamental principles of the PIV technique and comprehensive reviews on PIV can be found in numerous research articles (Keane and Adrian [3]; Raffel et al [4]; Prasad [5]).…”

Section: Introductionmentioning

confidence: 99%

“…Piirto et al [1] studied the effects of PIV IA size on turbulent quantities including the terms in the transport equation for the turbulent kinetic energy in a flow over a backward facing step. The IA sizes (l x · l y ) were 0.4 mm · 0.4 mm, 0.8 mm · 0.8 mm, 1.2 mm · 1.2 mm, and 1.6 mm · 1.6 mm which correspond to l y /g = 16, 32, 48 and 64, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of PIV interrogation area on turbulent statistics up to 4th order moments in smooth and rough wall turbulent flows

Shah

Agelin‐Chaab

Tachie

2008

Experimental Thermal and Fluid Science

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Section: Interrogation Area (Ia) Sizesmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of PIV interrogation area on turbulent statistics up to 4th order moments in smooth and rough wall turbulent flows

Shah

Agelin‐Chaab

Tachie

2008

Experimental Thermal and Fluid Science

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“…The mean reattachment point occurs where the streamline originating at the step edge impinges on the bottom wall. The statistical properties of turbulence for BFS flows have been studied extensively over the past two decades (Armali et al 1983;Nakagawa and Nezu 1987;Simpson 1989;Chun and Sung 1998) and continue to be the subject of active experimental and numerical studies (Scarano et al 1999;Spazzini et al 2001;Kostas 2002;Piirto et al 2003;Dejoan and Leschziner 2004;Furuichi et al 2004;Nezu 2005;Schram et al 2004;Sheu and Rani 2006).…”

Section: Introductionmentioning

confidence: 99%

The Effects of Canopy Leaf Area Index on Airflow Across Forest Edges: Large-eddy Simulation and Analytical Results

Cassiani

Katul

Albertson

2007

Boundary-Layer Meteorol

119

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The structure of turbulent flows along a transition between tall-forested canopies and forest clearings continues to be an active research topic in canopy turbulence. The difficulties in describing the turbulent flow along these transitions stem from the fact that the vertical structure of the canopy and its leaf area distribution cannot be ignored or represented by an effective roughness length. Large-eddy simulation (LES) runs were performed to explore the effect of a homogeneous variation in the forest leaf area index (LAI) on the turbulent flow across forest edges. A nested grid numerical method was used to ensure the development of a deep boundary layer above the forest while maintaining a sufficiently high resolution in the region close to the ground. It was demonstrated that the LES here predicted first-order and second-order mean velocity statistics within the canopy that agree with reported Reynolds-Averaged Navier-Stokes (RANS) model results, field and laboratory experiments. In the simulations reported here, the LAI was varied between 2 and 8 spanning a broad range of observed LAI in terrestrial ecosystems. By increasing the forest LAI, the mean flow properties both within the forest and in the clearing near the forest edge were altered in two fundamental ways: near the forest edge and into the clearing, the flow statistical properties resembled the so-called back-facing step (BFS) flow with a mean recirculation zone near the edge. Another recirculation zone sets up downstream of the clearing as the flow enters the tall forest canopy. The genesis of this within-forest recirculation zone can be primarily described using the interplay between the mean pressure gradients (forcing the flow) and the drag force (opposing the flow). Using the LES results, a simplified analytical model was also proposed to explain the location of the recirculation zone inside the canopy and its dependence on the forest LAI. Furthermore, a simplified scaling argument that decomposes the mean velocity at the outflow edge into a superposition of 'exit flow' and BFS-like flow with their relative importance determined by LAI was explored.

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“…According to Piirto et al [108], for an order of magnitude analysis similar to the one presented here, Λ can be estimated to be 0. repectively. In the above equations, ν is kinematic viscosity, and ε is turbulent dissipation rate, which can be estimated using the following equation [108]: …”

Section: Piv Systemmentioning

confidence: 55%

Experimental and Numerical Study of Flow Structures Associated With Low Aspect Ratio Elliptical Cavities

Khadivi¹,

Savory

2013

Journal of Fluids Engineering

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The flow regimes associated with a 2:1 aspect ratio, elliptical planform cavity in a turbulent flat plate boundary layer have been systematically examined for various depth/width ratios (0.1 to 1.0) and yaw angles (0° to 90°), using a combination of wind tunnel experiments (involving Particle Image Velocimetry and helium bubble visualization) and Computational Fluid Dynamics (CFD) simulations (employing threedimensional steady calculations with the Reynolds Stress model turbulence closure).Satisfactory agreement has been found between the results using the two methods, indicating that the steady numerical simulations can be a cost-effective tool to predict the mean flow features.The flow has been found to be highly dependent on yaw angle and cavity depth. For each of the three broad flow categories specified according to yaw angle, which include the symmetric flow regime (yaw angle = 0°), the straight vortex regime (yaw angle = 90°) and the asymmetric flow regime (15° ≤ yaw angle ≤ 60°) different regimes are found to exist, depending on cavity depth. For each combination of yaw angle and depth, the flow has been analyzed through investigation of shear layer parameters, the three-dimensional vortex structure, pressure distribution and drag, wake flow, and vortex oscillations.While the elliptical cavity flows have been found to have some similarities with those of nominally two-dimensional and rectangular cavities, the three-dimensional effects due to the low aspect ratio and curvature of the walls give rise to features exclusive to low aspect ratio elliptical cavities, including formation of cellular structures at intermediate depths and unique vortex structures within and downstream of the cavity.The three-dimensional flow structure of the flow is most pronounced in the asymmetric regimes with large yaw angles (45° and 60°). The dominant feature in this regime is the formation of a trailing vortex that is associated with high drag and flow oscillations within the cavity.iv Keywords

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Measuring turbulence energy with PIV in a backward-facing step flow

Cited by 41 publications

References 24 publications

Influence of PIV interrogation area on turbulent statistics up to 4th order moments in smooth and rough wall turbulent flows

Influence of PIV interrogation area on turbulent statistics up to 4th order moments in smooth and rough wall turbulent flows

The Effects of Canopy Leaf Area Index on Airflow Across Forest Edges: Large-eddy Simulation and Analytical Results

Experimental and Numerical Study of Flow Structures Associated With Low Aspect Ratio Elliptical Cavities

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