New techniques are developed to improve the velocity flow-field measurement capability within a freesurface boundary layer region on which progressive capillarygravity waves are present. Due to the extremely thin but rather vortical characteristics of the aforementioned boundary layer, conventional particle image velocimetry (PIV) methods fail to estimate velocity (and vorticity) vectors at an ...

A method is proposed that allows threedimensional (3D) two-component measurements to be made by means of particle image velocimetry (PIV) in any volume illuminated over a finite thickness. The method is based on decomposing the cross-correlation function into various contributions at different depths. Because the technique is based on 3D decomposition of the correlation function and not reconst...

the proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. in this paper, after a review of the taylor method, the restrictions and advantages of velocity measurement techniq...

The wavelet-based vector multiresolution technique was proposed and applied to the post-processing of PIV results for identifying the multi-scale turbulent structures. By analyzing the instantaneous streamlines and vorticity fields of various scales the important information on the multi-scale flow structures was obtained. The large-scale vortices or coherent structures with a central scale of ...

The wavelet-based vector multiresolution technique was applied to the postprocessing of PIV results for identifying the multiscale turbulent structures of a lobed jet. By analyzing the instantaneous streamlines and vorticity fields of various scales, we obtained important information on the multiscale flow structures. The large-scale vortices or coherent structures with a central scale of a = 1...

We present a holographic PIV system which extends the standard PIV analysis scheme of two velocity components (2D2C) to the third dimension and overcomes the disturbing background light in deep volume images reconstructed from particle holograms. In a light-in-flight holography (LiFH) setup the short coherence length of a modified laser source is used to suppress light from out-of-focus regions...

High Performance Computing (HPC) applications are mapped to a cluster of multi-core processors communicating using high speed interconnects. More computational power is harnessed with the addition of hardware accelerators such as Graphics Processing Unit (GPU) cards and Field Programmable Gate Arrays (FPGAs). Particle Image Velocimetry (PIV) is an embarrassingly parallel application that can be...

The evaluation of the instantaneous three-dimensional pressure field from tomographic PIV data relies on the accurate estimate of the Lagrangian acceleration. To date, techniques to reconstruct the Lagrangian trajectories from velocity fields obtained by Tomo-PIV have been used. Nevertheless, the reconstruction of relatively long trajectories, beneficial for the reduction of the precision error...

We analyze representative ill-posed scenarios of tomographic PIV with a focus on conditions for unique volume reconstruction. Based on sparse random seedings of a region of interest with small particles, the corresponding systems of linear projection equations are probabilistically analyzed in order to determine (i) the ability of unique reconstruction in terms of the imaging geometry and the c...

We introduce a novel class of algorithms for evaluating PIV image pairs. The mathematical basis is a continuous variational formulation for globally estimating the optical flow vector fields over the whole image. This class of approaches has been known in the field of image processing and computer vision for more than two decades but apparently has not been applied to PIV image pairs so far. We...