This research aims to measure four-dimensional, spatio-temporal velocity fields in unsteady periodic flows, such as those around rotorcraft. Periodic planar velocity fields at several slices of the flowfield are used to compute the component normal to the planes. The flow being incompressible, satisfying the continuity equation is sufficient. The velocity field reconstruction technique is valid...

The development of Doppler Global Velocimetry as a flow diagnostic measurement sy s t em nece s s i t a t ed seve ra l innova t i ons to so l ve problems found during wind tunnel testing. These innovations ranged from ratioing a data image with a reference image to remove scattered light variations, dewarping the images to remove optical distortions, and to the use of virtual wind tunnels creat...

Experimental observations of a purely elastic flow instability occurring in the lid-driven cavity flow of two semi-dilute polymer solutions are reported and the effect of cavity aspect ratio on the dynamical structure of the unstable flow is quantitatively investigated. The spatial and temporal characteristics of the secondary flow are measured using flow visualization, laser Doppler velocimetr...

This paper presents flow results of a magnetic resonance imaging velocimetry system which relies on fluid motion estimation, and uses vorticity map differencing for calibrating its reliability. To validate this new concept, phase contrast magnetic resonance imaging on the right atrium of a healthy subject has been suggested. The study has demonstrated the state of change in blood flow patterns ...

Objective: The purpose of this study was to determine the role of uterine artery Doppler flow velocimetry at second trimester of pregnancy in prediction of preeclampsia. Methods: This prospective study is carried out in the department of Radiodiagnosis, Krishna institute of Medical science, Karad. The study includes 220 pregnant women (primigravida) from August 2013 to September 2014 whose Uter...

An in-depth process analysis of water jetting, a promising cost-effective drilling method for the exploration geothermal reservoirs, is presented. The jetting analyzed under submerged and pressurized conditions by complementary high-speed shadow imaging, particle image velocimetry, rock erosion analysis. shadowgraphy velocimetry experiments show that nozzle cavitation dominates process, it can ...

Imaging flow velocity measurements are essential for the investigation of unsteady complex flow phenomena, e.g., in turbomachines, injectors and combustors. The direct optical measurement on fluid molecules is possible with laser Rayleigh scattering and the Doppler effect. However, the small scattering cross-section results in a low signal to noise ratio, which hinders time-resolved measurement...

A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow quantification of complex three-dimensional flow fields at video camera rates. The entire flow field structure within a selected plane is measured simultaneously rather than by scanned, point-by-point measurements using conventional laser velocimetry. To...

........................................................................................................................... iii Sammanfattning ............................................................................................................... iv 1. Objectives of the Work ............................................................................................ 1 2. Background .......