Surface Flow Visualization on a Full-Scale Passenger Car with Quantitative Tuft Image Processing

Wieser, Dirk; Bonitz, Sabine; Löfdahl, Lennart; Broniewicz, Alexander; Nayeri, Christian Navid; Paschereit, Christian Oliver; Larsson, Lars

doi:10.4271/2016-01-1582

Cited by 9 publications

(5 citation statements)

References 6 publications

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“…Here, mean tuft angles are also used to perform line integral convolution (LIC). Their results show good agreement between the calculated surface traces and oil film visualization as well as CFD simulations (Wieser et al 2016). Swytink-Binnema and Johnson (2016) determine the blade stall from captured videos of the tufts applied to a wind turbine blade.…”

Section: Introductionmentioning

confidence: 67%

“…They link the tuft angular standard deviation to the local turbulence level which allows for the determination of separation lines. Wieser et al apply a similar methodology to a realistic car model (Wieser et al 2015) and full-scale road vehicles (Wieser et al 2016). Here, mean tuft angles are also used to perform line integral convolution (LIC).…”

Section: Introductionmentioning

confidence: 99%

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Tuft deflection velocimetry: a simple method to extract quantitative flow field information

et al. 2020

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A novel method capable of assessing flow fields in a quick and relatively simple manner is introduced. In an extension to the classical qualitative flow visualization by means of cotton or polymeric tufts, digital data processing is used to extract the orientation of these tufts. This information can be related to physical quantities, in particular to time-and space-dependent velocity signals. The capability of this method is demonstrated in two test scenarios. First, it is applied to gain information on the unsteady near-wall flow along a turbulent separation bubble. Second, the two-component velocity field in the wake of a generic car model is measured, allowing for a quantification of the recirculation zone dimensions. Validation measurements with conventional techniques, e.g., particle image velocimetry, unsteady pressure measurements and hot wire anemometry, are conducted throughout the study. These generally suggest that the novel approach provides a quick and reasonably good quantitative overview of the flow configurations. However, the measurement error may be substantial in flow regions of low velocity or dominated by high-frequency oscillations.

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Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Tuft deflection velocimetry: a simple method to extract quantitative flow field information

et al. 2020

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“…However, because the camera was installed close to the car surface, the shapes of individual tufts could be acquired, which was the difference from the method of Vey et al (2014). In addition, although Wieser et al (2016) estimated the flow direction from the tuft shapes, they did not obtain the 3D coordinates of the tufts.…”

Section: Related Work and Contributionmentioning

confidence: 99%

“…As such, flow visualization is often criticized for lacking objectivity and quantitative detail. In order to address this problem, attempts have been made to quantify the tuft flow-visualization method (Vey et al 2014, Swytink-Binnema and Johnson 2016, Wieser et al 2016; these will be discussed in detail later. Of course, quantitative data obtained by CFD and PIV are often visualized qualitatively in some way to facilitate visual and empirical expert analysis.…”

Section: Motivation and Purposementioning

confidence: 99%

Extracting quantitative three-dimensional unsteady flow direction from tuft flow visualizations

Omata

Shirayama

2017

Fluid Dyn. Res.

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We focus on the qualitative but widely used method of tuft flow visualization, and propose a method for quantifying it using information technology. By applying stereo image processing and computer vision, the three-dimensional (3D) flow direction in a real environment can be obtained quantitatively. In addition, we show that the flow can be divided temporally by performing appropriate machine learning on the data. Acquisition of flow information in real environments is important for design development, but it is generally considered difficult to apply simulations or quantitative experiments to such environments. Hence, qualitative methods including the tuft method are still in use today. Although attempts have been made previously to quantify such methods, it has not been possible to acquire 3D information. Furthermore, even if quantitative data could be acquired, analysis was often performed empirically or qualitatively. In contrast, we show that our method can acquire 3D information and analyze the measured data quantitatively.

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“…This method is widely applied in aircraft design, wing testing, rotor/propeller design, automobile design, etc. [4][5][6][7][8][9][10][11][12]. It is a typical method that combines high resolution computer-aided techniques and flow measurement [13].…”

Section: Introductionmentioning

confidence: 99%

Digitalization and Quantitative Flow Visualization of Surrounding Flow over a Specially-Shaped Column-Frame by Luminescent Mini-Tufts Method

Chen

2022

Aerospace

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The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, mean field mini-tufts calculation, inclination angle calculation, oscillation area calculation, etc. The model is subjected to a newly proposed digitalization method and realized by in-house code. The time mean angle’s changing mode, along the mini-tuft, are analyzed, which shows that the mini-tuft follows the inflow well. The transient oscillation of mini-tufts is observed as well, which shows that on the middle part of the irregularity cylinder, the flow oscillates more intensively.

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Surface Flow Visualization on a Full-Scale Passenger Car with Quantitative Tuft Image Processing

Cited by 9 publications

References 6 publications

Tuft deflection velocimetry: a simple method to extract quantitative flow field information

Tuft deflection velocimetry: a simple method to extract quantitative flow field information

Extracting quantitative three-dimensional unsteady flow direction from tuft flow visualizations

Digitalization and Quantitative Flow Visualization of Surrounding Flow over a Specially-Shaped Column-Frame by Luminescent Mini-Tufts Method

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