Flow Image Velocimetry Method Based on Advection-Diffusion Equation

Bizjan, Benjamin; Orbanić, Alen; Širok, Brane; Bajcar, Tom; Novak, Lovrenc; Kovač, Boštjan

doi:10.5545/sv-jme.2013.1614

Cited by 6 publications

(8 citation statements)

References 16 publications

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“…Its variation showed no significant influence on calculated velocity fields, which indicates the advection dominated nature of the investigated flow. Effects of other settings in ADM-flow were analysed in detail in [4,5], where accuracy of the method was also evaluated on the basis of synthetic images. Analysis of vortex shedding in [4] resulted in global relative errors of up to 14% in vector magnitude and 15° in direction for the most difficult flow pattern (vortex).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Effects of other settings in ADM-flow were analysed in detail in [4,5], where accuracy of the method was also evaluated on the basis of synthetic images. Analysis of vortex shedding in [4] resulted in global relative errors of up to 14% in vector magnitude and 15° in direction for the most difficult flow pattern (vortex). In the present case, additional uncertainties are introduced from the experiment, where camera capabilities, especially frame rate, could prove to be important.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…The method is implemented into software ADM-flow, which provides all the required pre-and post-processing tools for application of the method through a graphical user interface. More information on the theoretical principles of calculation engine and verification of the method on simplified and realistic cases are given in Bizjan et al [4,5].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of vortex shedding from an airfoil by computational fluid dynamics simulation and computer-aided flow visualization

Novak¹,

Bajcar²,

Širok³

et al. 2018

Therm sci

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The article presents an experimental and numerical study of vortex generation and shedding from a NACA 4421 airfoil at low Reynolds number. The experiment was conducted in a low speed wind tunnel by flow visualization. A high speed camera was used to record flow structures at the airfoil trailing edge. The recorded images were processed with an in-house developed software based on the advection-diffusion equation to compute instantaneous 2-D velocity fields. These results were compared with results of the CFD simulation which employed the scale-adaptive simulation (SAS) turbulence modelling. The SST-SAS model produced finer and less stable turbulent structures compared to an URANS simulation with the shear stress transport model. Time averaged velocities and frequency spectra for the both models are in good agreement, but variability of flow in both time and frequency domain is higher in case of the SST-SAS model. Velocity fields computed on the basis of visualization show generally acceptable agreement with the CFD results. Higher errors occur in areas of unperturbed smoke trails and areas of high velocity gradients, however, the vortex shedding frequency is captured with excellent agreement to the experiment.

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Section: Experimental Set-upmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of vortex shedding from an airfoil by computational fluid dynamics simulation and computer-aided flow visualization

Novak¹,

Bajcar²,

Širok³

et al. 2018

Therm sci

Self Cite

View full text Add to dashboard Cite

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“…Such an approach enables both to significantly increase the reflectivity of measurement area illuminated by the light sheet and level down the requirements to light sheet power. However, in this case the cross-correlation algorithm employed by PIV appeared to be inapplicable to processing of video frames with continuous pixel intensity [5,6]. For this reason SIV employs not a sloping peak of the cross-correlation function but a sharp minimum of the functional of absolute differences in pixel intensities to estimate the displacement of interrogation windows with the accuracy up to one pixel.…”

Section: Introductionmentioning

confidence: 99%

Validation of SIV measurements of turbulent characteristics in the separation region

Dushin

Михеев

Душина

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Temporally and spatially resolved 2D measurements are important for the studies of complex turbulent flows. The recently developed SIV technique (Smoke Image Velocimetry), which is superior to PIV in some cases, can be used for this purpose. SIV validation results are presented for the steady turbulent backward-facing step flow measurements. Velocity profiles and Reynolds stress profiles are given for the regions of oncoming flow, reverse flow, flow reattachment and relaxation. The Reynolds number based on the step height and oncoming flow velocity at the boundary layer edge was Re h = 4834. The obtained data have been compared to LDA measurements and DNS.

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“…Bizjan et al [12] tested a flow image Velocimetry method based on advection-diffusion equation, on a much simpler airfoil than ours and compared the results with the CFD RANS simulation. They found that the used SST model provides good agreement with measured data for mean flow and that the used Velocimetry method is in good agreement with the true velocity field.…”

Section: Introductionmentioning

confidence: 99%

Optimization of SAE Formula Rear Wing

Iljaž

Škerget

Štrakl

et al. 2016

SV-JME

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This work deals with taking advantage of the available numerical methods when trying to excel in automotive competition. First, the optimization problem is outlined, to be followed by the proposed numerical solution, as well as the practical consequences of this solution, not as a proof of validity of the numerical approach, but rather as a description of a modern design flow.Formula SAE is an international competition having the common goal of designing and manufacturing of a racing car. While efforts have been made to keep the average velocity as low as possible, for safety reasons (around 50 km/h), by designing an especially tortuous track, there is fierce competition among competitors. This, rather low, velocity presents an additional challenge before the designerincreasing downforce results in higher corner speeds, and this, in turn, leads to better final times during the competition. The design criterion was, therefore, to construct, and manufacture a vehicle which exerted as much downforce as possible.The body of work related to the rear wings has been performed at Monash University see Wordley and Saunders [1]. However, their work covered 2D computational fluid dynamics (CFD) analysis citing availability of a full-scale wind tunnel. This approach, while completely understandable, is not suitable for those without access to such expensive facilities. We believe and have proven in this work, that similar results can be achieved using full-scale 3D CFD modeling. In addition, we believed that modeling rotating wheels and a moving road were absolutely necessary in order to achieve meaningful results. Also, Wordley and Saunders [1] were not concerned with optimization of height but were rather changing the angle of attack, such approach being understandable for wind tunnel tests. Doddegowda et al. [2] have also shown generally agreeable computational results without focusing on particular parts of the car. On the contrary, De Silva et al.[3] used CFD for fine-tuning of side panels in order to maximize the use of cooling air. They used moving ground however, not spinning wheels, which, in our opinion, is absolutely necessary to capture the vortex formation around the side walls of the car. The importance of a rotating wheel was, albeit from a different perspective, confirmed by Huminic and Chiru [4].The surprising scientific result shown herein is that the effect of the slat was more pronounced than the effect of the second flap, for the maximum angle of attack, at the upmost main rear wing position, and this is documented herein. Unfortunately, the final design could not incorporate this result as this would • Several different layouts were analyzed. Optimization of SAE Formula Rear Wing• The addition of a slat at the expense of a second flap results in significant increase of downforce (about 6 %).• Boundary layer separation causes a significant decrease in lift, and occurs for higher angles of attack in the case of using a slat as opposed to the case without a slat and with the second flap.

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Flow Image Velocimetry Method Based on Advection-Diffusion Equation

Cited by 6 publications

References 16 publications

Investigation of vortex shedding from an airfoil by computational fluid dynamics simulation and computer-aided flow visualization

Investigation of vortex shedding from an airfoil by computational fluid dynamics simulation and computer-aided flow visualization

Validation of SIV measurements of turbulent characteristics in the separation region

Optimization of SAE Formula Rear Wing

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