Papers by B. Van Oudheusden
Experiments in Fluids, 2014
ABSTRACT The objective of the method described in this work is to provide an improved reconstruct... more ABSTRACT The objective of the method described in this work is to provide an improved reconstruction of an original flow field from experimental velocity data obtained with particle image velocimetry (PIV) technique, by incorporating the local accuracy of the PIV data. The postprocessing method we propose is Kriging regression using a local error estimate (Kriging LE). In Kriging LE, each velocity vector must be accompanied by an estimated measurement uncertainty. The performance of Kriging LE is first tested on synthetically generated PIV images of a two-dimensional flow of four counter-rotating vortices with various seeding and illumination conditions. Kriging LE is found to increase the accuracy of interpolation to a finer grid dramatically at severe reflection and low seeding conditions. We subsequently apply Kriging LE for spatial regression of stereo-PIV data to reconstruct the three-dimensional wake of a flapping-wing micro air vehicle. By qualitatively comparing the large-scale vortical structures, we show that Kriging LE performs better than cubic spline interpolation. By quantitatively comparing the interpolated vorticity to unused measurement data at intermediate planes, we show that Kriging LE outperforms conventional Kriging as well as cubic spline interpolation.
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Bioinspiration & Biomimetics, 2012
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Journal of Experimental Biology, 2005
... MLA. Nature. Science. Click to zoom in 13 pages available to preview. Available from Florian ... more ... MLA. Nature. Science. Click to zoom in 13 pages available to preview. Available from Florian Muijres's profile on Mendeley. ... 288, pp. 100-106, 2000. 2. CP Ellington, C. Van den Berg, AP Willmott and ALR Thomas, Leading-Edge Vortices in Insect Flight, Nature, vol. 384, pp. ...
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International Journal of Micro Air Vehicles, 2014
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39th AIAA Fluid Dynamics Conference, 2009
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Physics of Fluids, 2014
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28th International Symposium on Shock Waves, 2012
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ABSTRACT Infrared thermography is used to determine the instantaneous transition location of a su... more ABSTRACT Infrared thermography is used to determine the instantaneous transition location of a supersonic flat plate boundary layer. In order to have sufficient contrast for the IR measurements a stainless steel plate is uniformly heated before the wind tunnel is started. During the run the plate cools down rapidly and the decreasing wall temperature stabilises the laminar boundary layer, causing a moving transition front. A linear relation between the transition location and wall temperature is found. The obtained results agree well with surface oil flow measurements that were carried out on a cold plate
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Sensors and Actuators A: Physical, 1992
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Shock Waves, 2011
ABSTRACT The spatio-temporal dynamics of an impinging shock/boundary layer interaction at Mach 2 ... more ABSTRACT The spatio-temporal dynamics of an impinging shock/boundary layer interaction at Mach 2 and under incipient separation conditions, has been investigated experimentally by means of high-speed particle image velocimetry (PIV). The available PIV acquisition rate of up to 20 kHz permits a time-resolved characterization of the interaction. The dynamics of different flow regions—notably the separation region and the reflected shock—were quantified by means of temporal auto-correlation fields and pseudo-spectral analysis. The PIV data further enable to investigate the relationship between spatially extended flow features, such as shock position and bubble size, as well as the influence of the upstream boundary layer. The results confirm earlier studies that there is an important upstream effect on the present incipient interaction. KeywordsShock wave boundary layer interaction–Particle image velocimetry
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Physics of Fluids, 2014
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Measurement Science and Technology, 1990
ABSTRACT
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Measurement Science and Technology, 2009
The unsteady organization and temporal dynamics of the interaction between a planar shock wave im... more The unsteady organization and temporal dynamics of the interaction between a planar shock wave impinging on a turbulent boundary layer at a free-stream Mach number of Me = 1.69 is investigated experimentally by means of dual-plane particle image velocimetry (dual-PIV). Two independent PIV systems were combined in a two-component mode to obtain instantaneous velocity fields separated by a prescribed small time delay. This enables us to obtain, in addition to mean and statistical flow properties, also instantaneously time-resolved data to characterize the temporal dynamics of the flow phenomenon in terms of time scales, temporal correlations and convective velocities. The characteristic time scales for the incoming boundary layer, the separation region and the reflected shock are determined by means of the temporal auto-correlation coefficient in the complete flow field for a range of time delays from 5 µs to 2000 µs. These auto-correlation fields are used to quantify the time scales in selected regions of the flow, with special interest for the vortex shedding and the low frequency reflected shock dynamics. This permits resolving the dominant time scales within the boundary layer and the interaction region.
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Journal of Fluids Engineering, 2004
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Journal of Fluid Mechanics, 2010
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Journal of Biomechanical Engineering, 2003
A new one-dimensional model is presented for the calculation of steady and unsteady flow through ... more A new one-dimensional model is presented for the calculation of steady and unsteady flow through an indented two-dimensional channel with separation and reattachment. It is based on an interactive boundary layer approach, where the equations for the boundary layer flow near the channel walls and for an inviscid core flow are solved simultaneously. This approach requires no semi-empirical inputs, such as the location of separation and reattachment, which is an advantage over other existing one-dimensional models. Because of the need of an inviscid core alongside the boundary layers, the type of inflow as well as the length of the channel and the value of the Reynolds number poses some limitations on the use of the new model. Results have been obtained for steady flow through the indented channel of Ikeda and Matsuzaki. In further perspective, it is discussed how the present model, in contrast to other one-dimensional flow models, can be extended to calculate the flow in nonsymmetrical channels, by considering different boundary layers on each of the walls.
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Experiments in Fluids, 2003
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Experiments in Fluids, 2012
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Papers by B. Van Oudheusden