scholarly journals Aerodynamic Characteristics and Lateral Displacements of a Set of Two Buildings in a Linked Tall Building System

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4046
Author(s):  
Zengshun Chen ◽  
Bubryur Kim ◽  
Dong-Eun Lee
Keyword(s):  
Particle Image ◽  
Lateral Displacement ◽  
Aerodynamic Characteristics ◽  
Induced Response ◽  
Wind Force ◽  
3 Dimensional ◽  
Image Velocimetry ◽  
Wind Flows ◽  
The Cross ◽  
Lateral Displacements

This study evaluates the aerodynamic characteristics and lateral displacements of two staggered buildings in a linked-building (LB) system. Particle image velocimetry and pressure measurements are employed, and the lateral displacement is evaluated using a 3-dimensional analytical model. When the gap distance between two non-linked buildings is small, the wind flows in a narrow jet, and a strong suction is generated on the inner surfaces of the two buildings, leading to a large cross-wind-induced response. However, the cross-wind-induced response is significantly reduced when a link is installed, because the suction forces generated from the buildings are in opposite directions and have a negative aerodynamic correlation. Conversely, with a large gap distance, the buildings at the front obstruct the wind blowing toward the rear buildings. Therefore, while the pressure distribution, wind-force coefficients, and wind-induced responses of the front and rear buildings show similar trends, the magnitude of impact on the front building is larger than that on the rear building. Installing a link is demonstrated to reduce the wind-induced response of the buildings in an LB system. However, the reduction in the along-wind-induced response is less than that in the cross-wind-induced response when the gap distance is small.

scholarly journals 3-dimensional particle image velocimetry based evaluation of turbulent skin-friction reduction by spanwise wall oscillation

2020 ◽  
Vol 32 (8) ◽  
pp. 085111
Author(s):  
Kushal U. Kempaiah ◽  
Fulvio Scarano ◽  
Gerrit E. Elsinga ◽  
Bas W. van Oudheusden ◽  
Leon Bermel
Keyword(s):  
Particle Image Velocimetry ◽  
Skin Friction ◽  
Particle Image ◽  
Friction Reduction ◽  
3 Dimensional ◽  
Image Velocimetry ◽  
Wall Oscillation ◽  
Skin Friction Reduction

Wake Behavior Around Flapping Wings of Model Hawkmoth Moving Sideways

2019 ◽  
Author(s):  
Jong-Seob Han ◽  
Jae-Hung Han
Keyword(s):  
Particle Image ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Digital Particle Image Velocimetry ◽  
Flapping Wings ◽  
Windward Side ◽  
Leeward Side ◽  
Image Velocimetry ◽  
Wake Interaction ◽  
Edge Vortex

Abstract This study investigated nearwake behaviors around flapping wings moving sideways. A dynamically scaled-up flapping manipulator was installed on a servo-driven towing carriage to give the sideways movement. In the single wing configuration, the wing in the windward side did not encounter any noticeable effects on the aerodynamic characteristics. The wing in the leeward side, on the other hand, experienced a substantial lift augmentation. We found a stretched leading-edge vortex (LEV) on the wing in the leeward side, implying the additional feeding flux into the LEV. In this case, the moving sideways gave a continuous lateral wind, which became the source to maintain the lift augmentation with the less downward component. We also found that the moving sideways rather intensified the interaction between the wake of the wing in the windward side and the contralateral wing, i.e., the wing-wake interaction. Accordingly, the lift augmentation on the wing in the leeward side practically disappeared by the wing-wake interaction. A digital particle image velocimetry for nearwake behaviors found the less developed trailing-edge shear layer and wingroot vortex traces. This implied that the massive downwash induced by the wing in the windward side was the main source to neutralize the lift augmentation on the contralateral wing.

An Experimental Investigation of the Permeability in Porous Chip Formed by Micropost Arrays Based on Microparticle Image Velocimetry and Micromanometer Measurements

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Haoli Wang ◽  
Pengwei Wang
Keyword(s):  
Cross Section ◽  
Particle Image ◽  
Brinkman Equation ◽  
Two Dimensional ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Microparticle Image Velocimetry ◽  
The Cross

Measurements of velocity and pressure differences for flows in porous chip fabricated with micropost arrays arranged in square pattern were implemented by using micro-particle image velocimetry (micro-PIV) and high precision micromanometer. Based on the measurement results, the permeability was solved by Brinkman equation under the averaged velocities over the cross section, two-dimensional velocities on the center plane of the microchannels, and the averaged velocities on the center plane considering the effect of depth of correlation (DOC), respectively. The experimental results indicate that the nondimensional permeability based on different velocities satisfies the Kozeny–Carman (KC) equation. The Kozeny factor is taken as 40 for the averaged velocity over the cross section and 15 for two kinds of center velocities based on the micropost array of this study, respectively. The permeability calculated by the velocities on the center plane is greater than that by the averaged velocity over the cross section.

Verification of Fully Developed Flow Entering Diffuser and Particle Image Velocimetry Procedures

2013 ◽  
Vol 465-466 ◽  
pp. 1352-1356 ◽  
Author(s):  
Normayati Nordin ◽  
Zainal Ambri Abdul Karim ◽  
Safiah Othman ◽  
Vijay R. Raghavan
Keyword(s):  
Particle Image ◽  
Abrupt Change ◽  
Laser Sheet ◽  
Settling Chamber ◽  
Mean Velocity ◽  
Fully Developed Flow ◽  
3 Dimensional ◽  
Image Velocimetry ◽  
The Mean ◽  
Good Agreement

3-Dstereoscopic PIV is capable of measuring 3-dimensional velocity components. Itinvolves a very sophisticated routine during setup, calibration, measurementand data processing phases. This paper aims to verify the 3-D stereoscopic PIVmeasurement procedures and to prove that the flow entering thediffuser is a fully developed flow. A diffuser inlet of rectangularcross-section, 130 mm x 50 mm is presently considered. For verification, thevelocities from PIV are compared with the velocities from pitot static probeand theory. The mean velocity obtained using pitot static probe is 2.44 m/s,whereas using PIV is 2.46 m/s. It thus gives the discrepancy of 0.8%. There isalso a good agreement between the mean velocity measured by PIV and theoreticalvalue with the discrepancy of 1.2%. This minor discrepancy is mainly due touncertainties in the experiments such as imperfect matching of coordinatesbetween the probe and laser sheet, unsteadiness of flow, variation in density andless precision in calibration. Basically, the operating procedures of 3-Dstereoscopic PIV have successfully been verified. Nevertheless, the flowentering diffuser is not perfectly developed due to the imperfect joining ductand the abrupt change of inlet cross-section introduced. Therefore, improvementto the existing rig is proposed by means of installing settling chamber withmultiple screens arrangement and contraction cone.

scholarly journals Effect of Gust Wind on Flow over a Wall-Mounted Fence

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Dhanush Bhamitipadi Suresh ◽  
Emmanuvel Joseph Aju ◽  
Matthew John Zaksek ◽  
Melissa Marie Leffingwell ◽  
Yaqing Jin
Keyword(s):  
Particle Image ◽  
Wind Gust ◽  
Wind Tunnel Experiments ◽  
Time Resolved ◽  
Wake Flows ◽  
Flow Mixing ◽  
Image Velocimetry ◽  
Before And After ◽  
Wind Flows ◽  
Streamwise Distance

In this work, the characteristics of incoming and wake flows downstream of wall-mounted fences under wind gust were explored with wind tunnel experiments. A time-resolved particle image velocimetry was used to capture the flow dynamics across two different fence heights. The results show that during the gust period, the wake presents distinct meandering and strong flow mixing. The Probability Density Function distribution of flow velocities indicates that the mixing effect increases with the streamwise distances. Specifically, for locations above the fence top tip, the growth of streamwise distance decreases the footprint of wind gust. However, for locations lower than the fence top tip, the local wind flows exhibit stronger variations before and after wind gust with the growth of downstream distance. Overall, at the same relative streamwise and spanwise locations downstream of fences within the wake region, the higher fence better suppresses the influence of gust wind.

Simultaneous measurement of wind velocity field and wind forces on a square tall building

2018 ◽  
Vol 21 (15) ◽  
pp. 2241-2258 ◽  
Author(s):  
Gongbo Zu ◽  
Kit Ming Lam
Keyword(s):  
Particle Image Velocimetry ◽  
Vortex Shedding ◽  
Large Scale ◽  
Particle Image ◽  
Phase Relationship ◽  
Tall Building ◽  
Wind Pressure ◽  
Wind Force ◽  
Force Relation ◽  
Image Velocimetry

Vortex shedding from a tall building is known to be responsible for the quasi-periodic across-wind force exerted on the building. This article unveils the exact relationship between the vortex shedding pattern and the fluctuating across-wind force. Simultaneous particle-image velocimetry and pressure measurements are carried out on a square-plan tall building model in the wind tunnel toward an understanding of the velocity–pressure–force relation for across-wind force generation on the building. A collection of instantaneous wind flow patterns and synchronized wind pressure distributions suggests the existence of full periods of vortex shedding from the building. The results are further analyzed using the conditional sampling method by which the roles of development and shedding of large-scale vortices in the building wake on the generation of peak across-wind forces are evidently found. Furthermore, quasi-periodicity of across-wind excitation is clearly confirmed with Hilbert transform of the across-wind force signal. The phase averaging technique is applied to the particle-image velocimetry flow fields and distinct vortex shedding patterns from the building are observed for most of the measurement time, together with an evident phase relationship with the across-wind forces.

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