Imaging Laser Doppler Velocimetry (ILDV) is a flow measurement technique which facilitates the measurement of one velocity component of a flow field in an imaging plane. It is an evolution of Heterodyne Doppler Global Velocimetry and may be regarded as the planar extension of the classical dual beam LDV by crossing two light sheets in the flow instead of focused laser beams. With different ligh...

Photoacoustic Doppler velocimetry provides a major opportunity to overcome limitations of existing blood flow measuring methods. By enabling measurements with high spatial resolution several millimetres deep in tissue, it could probe microvascular blood flow abnormalities characteristic of many different diseases. Although previous work has demonstrated feasibility in solid phantoms, measuremen...

A avaliação da vitalidade fetal é, sem dúvida, de grande utilidade em Obstetrícia, sendo a dopplervelocimetria um dos métodos disponíveis para essa finalidade. Na atualidade, apesar do reconhecimento da utilidade da dopplervelocimetria para avaliação do bem-estar fetal, tem sido necessário que se reflita sobre que casos realmente se beneficiam dessa tecnologia e também sobre algumas particulari...

In this paper we describe a method to measure fluid flow fields that we call Multi-Point Laser Doppler Anemometry (MPLDA). Like Doppler Global Velocimetry (DGV) and single point Laser Doppler Anemometry (LDA), the technique derives information from the Doppler shift observed when light is scattered from a moving particle and exploits the advantages of these techniques. The method retains the el...

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...

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...