In Background – Oriented Schlieren (BOS), distortions of a pattern are used to characterize flow fields containing refractive gradients. In the process, they can lead to some uncertainty. We proposed a method to quantify one aspect of uncertainty – that introduced when the density gradient...
This work introduces a method to estimate the uncertainty of the pressure fields reconstructed from particle image velocimetry / particle tracking velocimetry (PIV/PTV) measurements by propagating the instantaneous velocity vector uncertainty through the pressure reconstruction. The uncertainty propagations through the calculation and integration of pressure...
Particle Image Velocimetry (PIV) is a widely used non-invasive approach to finding a fluid flow velocity using tracer particles. Performing PIV measurement where the Signal-to-Noise Ratio (SNR) in the correlation plane is low can be unreliable and challenging. To address this issue, ensemble PIV has...
The uncertainty in a planar PIV measurement has been a topic of great interest in the last decade. Here, we present a new direct uncertainty estimation method for Particle Image Velocimetry (PIV), that uses the correlation plane as a model for the probability density function...
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...
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...
Background-Oriented Schlieren (BOS) is a technique used to measure fluid density from the apparent distortion of a target dot pattern. Here, we model how non-linearities in the density gradient fields can blur the dot pattern image and increase the position uncertainty. To develop this model,...
Most physical flows are complex and three-dimensional (3D) and all three velocity components (3C) are required to fully characterize the fluid motion. Stereo Particle Image Velocimetry (SPIV) is a non-invasive, 2D3C velocimetry measurement which offers a balance between accuracy -- 2D PIV fails to resolve...