The velocity and vorticity vector fields of a turbulent boundary layer. Part 1. Simultaneous measurement by hot-wire anemometry

Vukoslavčević, Petar; Wallace, J. M.; Balint, J. L.

doi:10.1017/s0022112091002628

Cited by 42 publications

(43 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present flow, the mean velocity gradient is smaller and this effect should be negligible, Since each X-probe is considered independently, the calibration procedure is the same as that for a standard X-probe. However, for other vorticity probes, which use from a minimum of 9 to a maximum of 20 hot wires (e.g., [ 18,19,35,36,38]), the velocity vector and its derivatives are estimated from a set of at least 9 nonlinear algebraic equations. The calibration procedures should be more complicated than for the present probe and the data processing is more time-consuming.…”

Section: Methodsmentioning

confidence: 99%

On the correlation between enstrophy and energy dissipation rate in a turbulent wake

Zhu

Antonia

1996

Appl. Sci. Res.

View full text Add to dashboard Cite

Abstract. All three components of the vorticity fluctuation have been measured simultaneously in a turbulent wake using a new eight-sensor vorticity probe. The vorticity fluctuation spectra agree reasonably well with those from a direct numerical simulation of a turbulent channel flow at high wavenumbers. The similarity between the instantaneous energy dissipation rate e and the instantaneous enstrophy ~O 2 is examined using spectra and probability density functions. The correlation between w z and e is evaluated in some detail. The homogeneous value of e is strongly correlated with w E. The full value of e and, more especially its isotropic value, are less well correlated with the enstrophy. Conditional averaging indicates that high enstrophy regions are associated with high energy dissipation rate regions.

show abstract

Section: Methodsmentioning

confidence: 99%

On the correlation between enstrophy and energy dissipation rate in a turbulent wake

Zhu

Antonia

1996

Appl. Sci. Res.

View full text Add to dashboard Cite

show abstract

“…The effects of the velocity gradients on multiple-sensor probe performances have been demonstrated by Vukoslav~evi6 and Wallace (1981) and Park and Wallace (1992). Vukoslav6evi6 et al (1991) used a nine-sensor probe to measure the spanwise and cross-stream velocity gradients in addition to the three components of the instantaneous velocity vector in a turbulent boundary-layer. They calculated the streamwise gradients from the temporal gradients using Taylor's hypothesis (Piomelli et al 1989), and thus were able to obtain all three components of the instantaneous vorticity vector as well.…”

Section: Nonuniform Velocity In the Sensing Volumethe Twelve-sensor Pmentioning

confidence: 99%

A calibration technique for multiple-sensor hot-wire probes and its application to vorticity measurements in the wake of a circular cylinder

Marasli

Nguyen

Wallace

1993

Experiments in Fluids

View full text Add to dashboard Cite

A calibration technique for multiple-sensor hot-wire probes is presented. The technique, which requires minimal information about the probe geometry, is tested using a four-sensor and a twelve-sensor probe. Two data reduction algorithms are introduced. The first one assumes a uniform velocity over the probe sensingvolume and is applied to the four-sensor probe measurements. The second one assumes a uniform velocity gradient over the sensing volume of the probe. The procedure, when applied to the twelvesensor probe, is shown to measure the velocity gradient components successfully. In both algorithms, the unknowns (velocity and velocity gradient components) are obtained by solving the resulting systems of nonlinear algebraic equations in a least-squares sense. The performances of the probes and the algorithms are tested with measurements in the wake of a circular cylinder. The statistics and spectra show that the twelve-sensor probe is successful in the simultaneous measurement of all three components of the velocity and all three components of the vorticity vectors.

show abstract

“…The complete velocity gradient tensor can be obtained at a single point using the multi-point hot-wire technique [Vukoslavcević et al, 1991;Tsinober et al, 1992]. The cinematographic stereoscopic PIV studies of Ganapathisubramani et al [2007Ganapathisubramani et al [ , 2008 performed stereo PIV measurements in a plane normal to the streamwise direction and used Taylor hypothesis to calculate the streamwise components of the velocity gradient tensor (with the other gradients computed in the plane of measurement).…”

Section: Introductionmentioning

confidence: 99%

The effects of resolution and noise on kinematic features of fine-scale turbulence

2011

View full text Add to dashboard Cite

The effect of spatial resolution and experimental noise on the kinematic fine scale features in shear flow turbulence is investigated by means of comparing numerical and experimental data. A direct numerical simulation (DNS) of a nominally two dimensional planar mixing layer is mean filtered onto a uniform Cartesian grid at four different, progressively coarser, spatial resolutions. Spatial gradients are then calculated using a simple second order scheme that is commonly used in experimental studies in order to make direct comparisons between the numerical and previously obtained experimental data. As expected, consistent with other studies, it is found that reduction of spatial resolution greatly reduces the frequency of high magnitude velocity gradients and thereby reduces the intermittency of the scalar analogues to strain (dissipation) and rotation (enstrophy). There is also an increase in the distances over which dissipation and enstrophy are spatially coherent in physical space as the resolution is coarsened, although these distances remain a constant number of grid points, suggesting that the data follows the applied filter. This reduction of intermittency is also observed in the eigenvalues of the strain-rate tensor as spatial resolution is reduced. The quantity with which these eigenvalues is normalised is shown to be extremely important as fine scale quantities, such as the Kolmogorov length scale, are showed to change with different spatial resolution. This leads to a slight change in the modal values for these eigenvalues when normalised by the local Kolmogorov scale, which is not observed when they are normalised by large scale, resolution independent quantities. The interaction between strain and rotation is examined by means of the joint pdf between the second and third invariants of the characteristic equation of the velocity gradient tensor, Q and R respectively and by the alignments between the eigenvectors of the strain-rate tensor and the vorticity vector. Gaussian noise is shown to increase the divergence error of a dataset and subsequently affect both the Q − R joint pdf and the magnitude of the alignment cosines.The experimental datasets are showed to behave qualitatively similarly to the numerical datasets to which Gaussian noise has been added, confirming the importance of understanding the limitations of coarsely resolved, noisy experimental data.

show abstract

The velocity and vorticity vector fields of a turbulent boundary layer. Part 1. Simultaneous measurement by hot-wire anemometry

Cited by 42 publications

References 33 publications

On the correlation between enstrophy and energy dissipation rate in a turbulent wake

On the correlation between enstrophy and energy dissipation rate in a turbulent wake

A calibration technique for multiple-sensor hot-wire probes and its application to vorticity measurements in the wake of a circular cylinder

The effects of resolution and noise on kinematic features of fine-scale turbulence

Contact Info

Product

Resources

About