Volumetric Particle Tracking Velocimetry (PTV) non-invasively measures the 3D velocity field by recording successive snapshots of the tracer particle motion using a multi-camera set-up. A key step in the measurement chain is reconstructing the 3D particle location using the multi-camera projected particle images. However, the...
Pressure measured from the cardiovascular system is widely used to diagnose disease. Pressure reconstruction methods are increasingly of interest with the development of 4D flow magnetic resonance imaging (MRI) which noninvasively measures time-resolved velocity fields in-vivo. However, several error sources and limitations inherent to in...
Estimating the probability density function (PDF) of the random motion of particles has many applications. For example, measuring diffusion, rheology, temperature, Reynolds stresses in turbulent flows, and uncertainty in velocity measurements. Current methods based on cross-correlation (CC) of image ensembles estimate an assumed Gaussian PDF's...
This article presents a method for three-dimensional confocal microscopy to study the kinematics of nanometer-sized molecules and particles that are of great interest to a wide range of biological systems and cellular mechanics but have heretofore been obscured by limitations in measurement technology. The correlation-based...
PIV uncertainty quantification is important for comparison with CFD simulations and engineering design, but is challenging due to the complex non-linear measurement chain which involves a large number of parameters. Multiple assessments show that none of the current methods can reliably predict the actual uncertainty...
We propose an improved density integration methodology for Background Oriented Schlieren (BOS) measurements that overcomes the noise sensitivity of the commonly used Poisson solver. The method employs a weighted least-squares (WLS) optimization of the 2D integration of the density gradient field by solving an over-determined...
We present an uncertainty quantification methodology for density estimation from Background-Oriented Schlieren (BOS) measurements, in order to provide local, instantaneous, a posteriori uncertainty bounds on each density measurement in the field of view. Displacement uncertainty quantification algorithms from cross-correlation-based particle image velocimetry are used to...
We present a ray tracing image generation methodology for rendering realistic images of particle image velocimetry (PIV) and background oriented schlieren (BOS) experiments in the presence of density/refractive index gradients. This methodology enables the simulation of experiments for experimental design, error, and uncertainty analysis. Images...
Background-Oriented Schlieren (BOS) is used to measure fluid density from the apparent distortion of a target dot pattern. Here, we propose a new displacement estimation methodology based on tracking individual dots on the pattern as opposed to conventional cross-correlation algorithms. As dot patterns used in...
Cavitation is ubiquitous in nature and engineering systems and governs processes from corrosion in propeller blades to drugs getting through the endothelial cells. Since the collapse of the cavitation bubble is so violent that it generates an intense shock wave and induces high shear stress...