Unstable jet–edge interaction. Part 1. Instantaneous pressure fields at a single frequency

Ruhi Kaykayoglu; Donald Rockwell

doi:10.1017/s0022112086000563

Instantaneous pressure fields at a corner associated with vortex impingement

Journal of Fluid Mechanics ◽

10.1017/s0022112083000105 ◽

1983 ◽

Vol 126 ◽

pp. 187-204 ◽

Cited By ~ 29

Author(s):

Y.-P. Tang ◽

D. Rockwell

Keyword(s):

Flow Visualization ◽

Pressure Fluctuations ◽

Vortex Formation ◽

Maximum Amplitude ◽

Front Face ◽

Secondary Vortex ◽

Local Pressure ◽

Pressure Fields ◽

Instantaneous Pressure

The impingement of concentrations of vorticity upon a corner is studied using simultaneous flow visualization and correlation of pressure fluctuations, revealing the relations between the instantaneous pressure fields along the top and front faces of the corner and the instantaneous distortion of the incident vortex.By varying the transverse offset of the corner relative to the incident vortex, several distinct and consistent patterns of incident vortex–corner interaction are evident. The corresponding form and phasing of the instantaneous pressure fields are strongly dependent upon the nature of the vortex–corner interaction, though the maximum amplitude on the top and front faces is always of the same order. For certain interactions, there is separation of flow from the edge of the corner, as well as from the front face of the corner, leading to secondary-vortex formation and corresponding peaks in the local pressure fields.By integrating the instantaneous pressure fields along the top and front faces of the corner, the phasing between the respective forces is shown to exhibit varying degrees of dipole-like behaviour, depending upon the character of the incident vortex–corner interaction. Amplitudes of the corresponding moments of the pressure fields are remarkably insensitive to this interaction.

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Vortices incident upon a leading edge: instantaneous pressure fields

Journal of Fluid Mechanics ◽

10.1017/s002211208500218x ◽

1985 ◽

Vol 156 (-1) ◽

pp. 439 ◽

Cited By ~ 22

Author(s):

Ruhi Kaykayoglu ◽

Donald Rockwell

Keyword(s):

Leading Edge ◽

Pressure Fields ◽

Instantaneous Pressure

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Uncertainty of PIV/PTV based pressure, using velocity uncertainty

14th International Symposium on Particle Image Velocimetry ◽

10.18409/ispiv.v1i1.148 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Jiacheng Zhang ◽

Sayantan Bhattacharya ◽

Pavlos Vlachos

Keyword(s):

Boundary Condition ◽

Pressure Gradient ◽

Velocity Measurement ◽

Pressure Field ◽

Uncertainty Estimation ◽

Linear Transformations ◽

Reconstruction Process ◽

Pressure Fields ◽

Pressure Boundary Condition ◽

Instantaneous Pressure

Pressure reconstruction from velocity measurements using particle image velocimetry (PIV) and particle tracking velocimetry (PTV) has drawn significant attention as it can provide instantaneous pressure fields without altering the flow. Previous studies have found that the accuracy of the calcualted pressure field depends on several factors including the accuarcy of the velocity measurement, the spatiotemporal resolutions, the method for calculating pressure-gradient, the algorithm for pressure-gradient integration, the pressure boundary condition, etc. Therefore, it is critical and challenging to quantify the uncertainty of the reconstructed pressure field. The recent development of the uncertainty quantification algorithms for PIV and PTV allows for the local and instantaneous uncertainty estimation of velocity measurement, which can be used to infer the pressure uncertainty. In this study, we introduce a framework that propagates the standard velocity uncertainty defined as the standard deviation of the velocity error distribution through the pressure reconstruction process to obtain the uncertainty of the pressure field. The uncertainty propagations through the calculation of the pressure-gradient and the pressure-gradient integration were modeled as linear transformations, which can reproduce the effects of the spatiotemporal resolutions, the numerical schemes, the integration algorithms, and the pressure boundary condition on the accuracy of the resulting pressure fields. The proposed uncertainty estimation approach also considers the effect of the spatiotemporal and componentwise correlation of the velocity errors in common PIV/PTV measurements on the pressure uncertainty.

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