A WIND TUNNEL STUDY OF NATURAL VENTILATION FOR MULTI–SPAN GREENHOUSE SCALE MODELS USING TWO–DIMENSIONAL PARTICLE IMAGE VELOCIMETRY (PIV)

2003 ◽  
Vol 46 (3) ◽  
Author(s):  
I. Lee ◽  
S. Sase ◽  
L. Okushima ◽  
A. Ikeguchi ◽  
K. Choi ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
Natural Ventilation ◽  
Particle Image ◽  
Two Dimensional ◽  
Image Velocimetry ◽  
Scale Models ◽  
Wind Tunnel Study

scholarly journals Aerodynamics of manoeuvring flight in brown long-eared bats ( Plecotus auritus )

2018 ◽  
Vol 15 (148) ◽  
pp. 20180441 ◽  
Author(s):  
Per Henningsson ◽  
Lasse Jakobsen ◽  
Anders Hedenström
Keyword(s):  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
High Speed ◽  
Particle Image ◽  
Future Studies ◽  
Image Velocimetry ◽  
Mechanistic Basis

In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat. We found instead that the bats more often used the upstroke than they used the downstroke for this. We also found that the bats used both drag/thrust-based and lift-based asymmetries to perform the manoeuvre and that they even frequently switch between these within the course of a manoeuvre. We conclude that the bats used three main modes: lift asymmetries during downstroke, thrust/drag asymmetries during downstroke and thrust/drag asymmetries during upstroke. For future studies, we hypothesize that lift asymmetries are used for fast turns and thrust/drag for slow turns and that the choice between up- and downstroke depends on the timing of when the bat needs to generate asymmetries.

Abstract 14952: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ahmad Falahatpisheh ◽  
Arash Kheradvar
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Contrast Echocardiography ◽  
Ultrasound Contrast Agent ◽  
Three Dimensions ◽  
Small Scale ◽  
High Temporal Resolution ◽  
Two Dimensional ◽  
Particle Image Velocimetry Technique ◽  
Image Velocimetry

Introduction: The two-dimensional (2D) echocardiographic particle image velocimetry technique that was introduced in 2010 received much attention in clinical cardiology. Cardiac flow visualization based on contrast echocardiography results in images with high temporal resolution that are obtainable at relatively low cost. This makes it an ideal diagnostic and follow-up tool for routine clinical use. However, cardiac flow in a cardiac cycle is multidirectional with a tendency to spin in three dimensions rather than two-dimensional curl. Here, for the first time, we introduce a volumetric echocardiographic particle image velocimetry technique that robustly acquires the flow in three spatial dimensions and in time: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV). Methods: V-Echo-PIV technique utilizes matrix array 3D ultrasound probes to capture the flow seeded with an ultrasound contrast agent (Definity). For this feasibility study, we used a pulse duplicator with a silicone ventricular sac along with bioprosthetic heart valves at the inlet and outlet. GE Vivid E9 system with an Active Matrix 4D Volume Phased Array probe at 30 Hz was used to capture the flow data (Figure 1). Results: The 3D particle field was obtained with excellent spatial resolution without significant noise (Figure 1). 3D velocity field was successfully captured for multiple cardiac cycles. Flow features are shown in Figure 2 where the velocity vectors in two selected slices and some streamlines in 3D space are depicted. Conclusions: We report successful completion of the feasibility studies for volumetric echocardiographic PIV in an LV phantom. The small-scale features of flow in the LV phantom were revealed by this technique. Validation and human studies are currently in progress.

Flow analysis of two-dimensional pulsed jets by particle image velocimetry

2001 ◽  
Vol 31 (5) ◽  
pp. 519-532 ◽  
Author(s):  
J. C. Béra ◽  
M. Michard ◽  
N. Grosjean ◽  
G. Comte-Bellot
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Flow Analysis ◽  
Two Dimensional ◽  
Pulsed Jets ◽  
Image Velocimetry

Vortex wakes of birds: recent developments using digital particle image velocimetry in a wind tunnel

2006 ◽  
Vol 56 (4) ◽  
pp. 535-549 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
Particle Image ◽  
Lift Coefficient ◽  
Time History ◽  
Digital Particle Image Velocimetry ◽  
Wake Vortices ◽  
Image Velocimetry ◽  
Recent Developments ◽  
Size And Morphology

AbstractA flying animal generates a trail of wake vortices that contain information about the time history and magnitude of aerodynamic forces developed on the wings and body. Methods for visualising and recording wake vortices have been developed, allowing quantitative measurements by digital particle image velocimetry (DPIV). Results from DPIV experiments in a wind tunnel are presented for four passerine species of differing size and morphology. The normalised vorticity and its integrated quantity, circulation (Γ) both decline gradually with increasing flight speed. The measured circulations are successfully explained by a simple aerodynamic model where a normalised circulation, Γ/Uc, represents half the time-averaged lift coefficient, which is >2 at 4 m s−1 for a thrush nightingale.

Two-dimensional shear rate field and flow structures of a pseudoplastic fluid in a stirred tank using particle image velocimetry

2021 ◽  
pp. 117198
Author(s):  
Jenniffer S. Ayala ◽  
Helder L. de Moura ◽  
Rodrigo de L. Amaral ◽  
Francisco de A. Oliveira Júnior ◽  
José R. Nunhez ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Shear Rate ◽  
Particle Image ◽  
Stirred Tank ◽  
Flow Structures ◽  
Two Dimensional ◽  
Pseudoplastic Fluid ◽  
Image Velocimetry
Sign in / Sign up

Export Citation Format

Share Document