Pressure/velocity coupling induced by a near wall wake

Ruiz, Tony; Sicot, Christophe; Brizzi, Laurent-Emmanuel; Borée, Jacques; Gervais, Yves

doi:10.1007/s00348-010-0820-5

Cited by 28 publications

(9 citation statements)

References 23 publications

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“…The corrected signal is obtained by convolving the impulse response with the measured signal. The methodology has been successfully applied in the literature (Ruiz et al 2010). The distortion of recorded signals is inferred from the spectrum of the transfer function.…”

Section: Pressure Sensorsmentioning

confidence: 99%

Drag reduction of a car model by linear genetic programming control

Noack

Cordier

et al. 2017

Exp Fluids

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We investigate open-and closed-loop active control for aerodynamic drag reduction of a car model. Turbulent flow around a blunt-edged Ahmed body is examined at Re H ≈ 3 × 10 5 based on body height. The actuation is performed with pulsed jets at all trailing edges combined with a Coanda deflection surface. The flow is monitored with pressure sensors distributed at the rear side. We apply a model-free control strategy building on Dracopoulos & Kent (1997) and Gautier et al. (2015). The optimized control laws comprise periodic forcing, multi-frequency forcing and sensor-based feedback including also time-history information feedback and combination thereof. Key enabler is linear genetic programming as simple and efficient framework for multiple inputs (actuators) and multiple outputs (sensors). The proposed linear genetic programming control can select the best open-or closed-loop control in an unsupervised manner. Approximately 33% base pressure recovery associated with 22% drag reduction is achieved in all considered classes of control laws. Intriguingly, the feedback actuation emulates periodic high-frequency forcing by selecting one pressure sensor in the optimal control law. Our control strategy is, in principle, applicable to all multiple actuators and sensors experiments.

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Section: Pressure Sensorsmentioning

confidence: 99%

Drag reduction of a car model by linear genetic programming control

Noack

Cordier

et al. 2017

Exp Fluids

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“…Those sensors, are differential with a bandwidth of [0 Hz to 1.6 kHz] and a pressure range of 250 Pa. Details of the methodology are provided in Ruiz et al (2010). The maximal error on fluctuating pressure is evaluated at 9.4 Pa.…”

Section: Fluctuating Pressure Measurementmentioning

confidence: 99%

Wall pressure and conditional flow structures downstream of a reattaching flow region

Sicot

Perrin

Tran

et al. 2012

International Journal of Heat and Fluid Flow

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“…In the present case, the mode pair amplitudes depicted in Fig. 6a do not have a circumferential distribution, but fill a circular disk in the normalized amplitude plane, which can be due to amplitude [16] and/or frequency modulation [8]. The phasing ϕ n of each snapshot can now be extracted from the normalized amplitude plane via the four-quadrant inverse tangent: Figure 6b shows the fluctuation velocity in y direction (V -component) of an average of snapshots within a 15…”

Section: Resultsmentioning

confidence: 90%

“…The eigenvalues λ j are a measure of the contribution of the corresponding mode to the total fluctuating energy and thus, by sorting the modes in order of decreasing eigenvalues, the most dominant structures are revealed. Traveling structures will appear as two similar modes spatially shifted with respect to each other [16]. The eigenvalues of such a mode pair will be in the same order of magnitude.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Investigations of Tonal Noise on a Vehicle Side Mirror

Werner

Würz

Krämer

2016

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Experimental investigations on an isolated vehicle side mirror model are performed in a low turbulence wind tunnel aiming at the identification of the acoustic source mechanism leading to tonal noise emission. A combination of acoustic measurements and Particle Image Velocimetry shows that the discrete frequency noise can be related to the presence of a laminar boundary layer separation extending up to the trailing edge on the mirror's side surface and upper side. In the vicinity of the trailing edge, the shear layer develops into a vortical structure, which impinges on the trailing edge. By utilization of Proper Orthogonal Decomposition on the ensembles of instantaneous velocity fields and application of a phase sorting method, the length scales of the vortical structures could be extracted and related to the acoustic radiation. Order of magnitude analyses show parallels to the acoustic feedback mechanism known from the NACA 0012 airfoil.

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Pressure/velocity coupling induced by a near wall wake

Cited by 28 publications

References 23 publications

Drag reduction of a car model by linear genetic programming control

Drag reduction of a car model by linear genetic programming control

Wall pressure and conditional flow structures downstream of a reattaching flow region

Experimental Investigations of Tonal Noise on a Vehicle Side Mirror

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