Measurement of two overlapped velocity vector fields in microfluidic devices using time-resolved PIV

2008 ◽  
Vol 11 (1) ◽  
pp. 33-34 ◽  
Author(s):  
N. Erkan ◽  
K. Shinohara ◽  
K. Okamoto ◽  
T. Okamoto ◽  
T. Fujii
Keyword(s):  
Velocity Vector ◽  
Vector Fields ◽  
Microfluidic Devices ◽  
Time Resolved

Reconstructing Three-Dimensional Fluid Velocity Vector Fields from Acoustic Transmission Measurements

1977 ◽  
pp. 307-326 ◽  
Author(s):  
S. A. Johnson ◽  
J. F. Greenleaf ◽  
C. R. Hansen ◽  
W. F. Samayoa ◽  
M. Tanaka ◽  
...  
Keyword(s):  
Velocity Vector ◽  
Vector Fields ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Acoustic Transmission ◽  
Transmission Measurements

scholarly journals In vivo velocity vector imaging and time-resolved strain rate measurements in the wall of blood vessels using MRI

2011 ◽  
Vol 44 (5) ◽  
pp. 979-983 ◽  
Author(s):  
Stéphane Avril ◽  
Fabien Schneider ◽  
Christian Boissier ◽  
Zhi-Yong Li
Keyword(s):  
Strain Rate ◽  
Blood Vessels ◽  
Velocity Vector ◽  
Time Resolved ◽  
Velocity Vector Imaging

scholarly journals Microfluidic Devices for Time-Resolved Cryo-Electron Microscopy

2009 ◽  
Vol 96 (3) ◽  
pp. 411a-412a
Author(s):  
Zonghuan Lu ◽  
David Barnard ◽  
Tanvir R. Shaikh ◽  
Hisham Mohamed ◽  
Xing Meng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Microfluidic Devices ◽  
Time Resolved ◽  
Cryo Electron Microscopy

scholarly journals On the Application of Proper Orthogonal Decomposition (POD) for In-Cylinder Flow Analysis

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2261 ◽  
Author(s):  
Mohammed El-Adawy ◽  
Morgan Heikal ◽  
A. A. Aziz ◽  
Ibrahim Adam ◽  
Mhadi Ismael ◽  
...  
Keyword(s):  
Physical Properties ◽  
Proper Orthogonal Decomposition ◽  
Pressure Difference ◽  
Velocity Vector ◽  
Vector Fields ◽  
Orthogonal Decomposition ◽  
Stereoscopic Particle Image Velocimetry ◽  
Pod Analysis ◽  
Cylinder Flow ◽  
Proper Orthogonal

Proper orthogonal decomposition (POD) is a coherent structure identification technique based on either measured or computed data sets. Recently, POD has been adopted for the analysis of the in-cylinder flows inside internal combustion engines. In this study, stereoscopic particle image velocimetry (Stereo-PIV) measurements were carried out at the central vertical tumble plane inside an engine cylinder to acquire the velocity vector fields for the in-cylinder flow under different experimental conditions. Afterwards, the POD analysis were performed firstly on synthetic velocity vector fields with known characteristics in order to extract some fundamental properties of the POD technique. These data were used to reveal how the physical properties of coherent structures were captured and distributed among the POD modes, in addition to illustrate the difference between subtracting and non-subtracting the ensemble average prior to conducting POD on datasets. Moreover, two case studies for the in-cylinder flow at different valve lifts and different pressure differences across the air intake valves were presented and discussed as the effect of both valve lifts and pressure difference have not been investigated before using phase-invariant POD analysis. The results demonstrated that for repeatable flow pattern, only the first mode was sufficient to reconstruct the physical properties of the flow. Furthermore, POD analysis confirmed the negligible effect of pressure difference and subsequently the effect of engine speed on flow structures.

scholarly journals Optical-flow analysis toolbox for characterization of spatiotemporal dynamics in mesoscale optical imaging of brain activity

2016 ◽  
Author(s):  
Navvab Afrashteh ◽  
Samsoon Inayat ◽  
Mostafa Mohsenvand ◽  
Majid H. Mohajerani
Keyword(s):  
Optical Flow ◽  
Optical Imaging ◽  
Velocity Vector ◽  
Vector Fields ◽  
Brain Activity ◽  
Simulated Data ◽  
Spatiotemporal Dynamics ◽  
Sources And Sinks ◽  
Quantitative Analyses ◽  
Sensory Evoked

AbstractWide-field optical imaging techniques constitute powerful tools to sample and study mesoscale neuronal activity. The sampled data constitutes a sequence of image frames in which one can perceive the flow of brain activity starting and terminating at source and sink locations respectively. The most common data analyses include qualitative assessment to identify sources and sinks of activity as well as their trajectories. The quantitative analyses is mostly based on computing the temporal variation of the intensity of pixels while a few studies have also reported estimates of wave motion using optical-flow techniques from computer vision. A comprehensive toolbox for the quantitative analyses of mesoscale brain activity data however is still missing. We present a graphical-user-interface based Matlab® toolbox for investigating the spatiotemporal dynamics of mesoscale brain activity using optical-flow analyses. The toolbox includes the implementation of three optical-flow methods namely Horn-Schunck, Combined Local-Global, and Temporospatial algorithms for estimating velocity vector fields of perceived flow in mesoscale brain activity. From the velocity vector fields we determine the locations of sources and sinks as well as the trajectories and temporal velocities of activity flow. Using our toolbox, we compare the efficacy of the three optical-flow methods for determining spatiotemporal dynamics by using simulated data. We also demonstrate the application of optical-flow methods onto sensory-evoked calcium and voltage imaging data. Our results indicate that the combined local-global method we employ, yields results that correlate with the manual assessment. The automated approach permits rapid and effective quantification of mesoscale brain dynamics and may facilitate the study of brain function in response to new experiences or pathology.Conflicts of InterestnoneAuthor contribution statementMHM, MM, NV, and SI designed the study. NA and SI wrote Matlab® code for the toolbox and designed the simulated data. MHM, and NA performed the experiments. NA and SI analyzed the data. SI, NA, and MHM wrote the manuscript.

Incipient stall characterization from skin-friction maps

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Massimo Miozzi ◽  
Alessandro Capone ◽  
Christian Klein ◽  
Marco Costantini
Keyword(s):  
Skin Friction ◽  
Vector Fields ◽  
Three Dimensional ◽  
Suction Side ◽  
Temperature Sensitive ◽  
Flow Conditions ◽  
Time Resolved ◽  
Content Type ◽  
Fundamental Information ◽  
Taylor Hypothesis

Purpose The purpose of this study is the characterization of the dramatic variation in the flow scenario occurring at incipient stall conditions on a NACA0015 hydrofoil at moderate Reynolds numbers via the experimental analysis of time- and space-resolved skin-friction maps. The examined flow conditions are relevant for a variety of applications, including renewable energy production and unmanned and micro-aerial vehicles. Design/methodology/approach Grounding on the global temperature data acquired via temperature-sensitive paint, the proposed methodology adopts two approaches: one to obtain time-resolved, relative skin-friction vector fields by means of an optical-flow-based algorithm and the other one to extract quantitative, time-averaged skin-friction maps after minimization of the dissimilarity between the observed passive transport of temperature fluctuations and that suggested by the Taylor hypothesis. Findings Through the synergistic application of the proposed methods, the time-dependent evolution of the incipient stall over the hydrofoil suction side is globally described by firstly identifying the trailing edge separation at an angle of attack (AoA) AoA = 11.5°, and then by capturing the onset of upstream oriented, mushroom-like structures at AoA = 13°. The concomitant occurrence of both scenarios is found at the intermediate incidence AoA = 12.2°. Originality/value The qualitative, time-resolved skin-friction topology, combined with the quantitative, time-averaged distribution of the streamwise friction velocity, enables to establish a portrait of the complex, three-dimensional, unsteady scenario occurring at the examined flow conditions, thus providing new, fundamental information for a deeper understanding of the incipient stall development and for its control.

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