scholarly journals Effects of surgical masks on aerosol dispersion in professional singing

2021 ◽  
Author(s):  
Stefan Kniesburges ◽  
Patrick Schlegel ◽  
Gregor Peters ◽  
Caroline Westphalen ◽  
Bernhard Jakubaß ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Light ◽  
Near Field ◽  
Light Sheet ◽  
Laser Light Sheet ◽  
Professional Singers ◽  
Surgical Masks ◽  
Aerosol Dispersion ◽  
Airborne Viruses ◽  
Temporal Dispersion

Abstract Background In the CoVID-19 pandemic, singing came into focus as a high-risk activity for the infection with airborne viruses and was therefore forbidden by many governmental administrations. Objective The aim of this study is to investigate the effectiveness of surgical masks regarding the spatial and temporal dispersion of aerosol and droplets during professional singing. Methods Ten professional singers performed a passage of the Ludwig van Beethoven’s “Ode of Joy” in two experimental setups—each with and without surgical masks. First, they sang with previously inhaled vapor of e-cigarettes. The emitted cloud was recorded by three cameras to measure its dispersion dynamics. Secondly, the naturally expelled larger droplets were illuminated by a laser light sheet and recorded by a high-speed camera. Results The exhaled vapor aerosols were decelerated and deflected by the mask and stayed in the singer’s near-field around and above their heads. In contrast, without mask, the aerosols spread widely reaching distances up to 1.3 m. The larger droplets were reduced by up to 86% with a surgical mask worn. Significance The study shows that surgical masks display an effective tool to reduce the range of aerosol dispersion during singing. In combination with an appropriate aeration strategy for aerosol removal, choir singers could be positioned in a more compact assembly without contaminating neighboring singers all singers.

Visualization of Internal Flow Field of Propeller Fan

2017 ◽  
Author(s):  
Takaya Onishi ◽  
H. Sato ◽  
M. Hayakawa ◽  
Y. Kawata
Keyword(s):  
Flow Field ◽  
High Performance ◽  
Laser Light ◽  
Internal Flow ◽  
Light Sheet ◽  
Tip Vortex ◽  
Laser Light Sheet ◽  
Blade Surface ◽  
Similar Tendency ◽  
Flow Phenomena

Propeller fans are required not only to have high performance but also to be extremely quiet. The internal flow field of ventilation propeller fans is even more complicated because they usually have a very peculiar configuration with protruding blades upstream. Thus, many kinds of internal vortices yield which cause noise and their cause and countermeasures are needed to be clarified. The purposes of this paper are to visualize the internal flow of the propeller fan from the static and rotating frame of reference. The internal flow visualization measured from the static frame gives approximately the scale of the tip vortex. The visualization from the rotating coordinate system yields a better understanding of the flow phenomena occurring at the specific blade. The experiment is implemented by using a small camera mounted on the shaft of the fan and rotated it to capture the behavior of the vortices using a laser light sheet to irradiate the blade surface. Hence, the flow field of the specific blade could be understood to some extent. The visualized results are compared with the CFD results and these results show a similar tendency about the generation point and developing process of the tip vortex. In addition, it is found that the noise measurement result is relevant to the effect of tip vortex from the visualization result.

Locomotion in scombrid fishes: visualization of flow around the caudal peduncle and finlets of the chub mackerel Scomber japonicus

2001 ◽  
Vol 204 (13) ◽  
pp. 2251-2263 ◽  
Author(s):  
Jennifer C. Nauen ◽  
George V. Lauder
Keyword(s):  
Laser Light ◽  
Light Sheet ◽  
Flow Speed ◽  
The Body ◽  
Scomber Japonicus ◽  
Laser Light Sheet ◽  
Chub Mackerel ◽  
Caudal Peduncle ◽  
Local Flow ◽  
Scombrid Fishes

SUMMARY Scombrid fishes are known for high-performance locomotion; however, few data are available on scombrid locomotor hydrodynamics. In this paper, we present flow visualization data on patterns of water movement over the caudal peduncle and finlets (small fins on the dorsal and ventral body margin anterior to the caudal fin). Chub mackerel, Scomber japonicus, ranging in fork length from 20 to 26 cm, swam steadily at 1.2forklengthss−1 in a recirculating flow tank. Small, reflective particles in the flow tank were illuminated by a vertical (xy) or horizontal (xz) laser light sheet. Patterns of flow in the region near the caudal peduncle were measured using digital particle image velocimetry. Patterns of flow along the peduncle and finlets were quantified using manual particle tracking; more than 800 particles were tracked for at least 12ms over a series of tailbeats from each of four fish. In the vertical plane, flow trajectory and flow speed were independent of the position of the finlets, indicating that the finlets did not redirect flow or affect flow speed. Along, above and below the trailing surface of the peduncle, where the finlets were oriented along the peduncular surface, flow was convergent. Along, above and below the leading surface of the peduncle, where the finlets were absent, the flow trajectory was effectively horizontal. The lack of divergent flow on the leading surface of the peduncle is consistent with cross-peduncular flow formed by the lateral motion of the peduncle interacting with convergent flow resulting from forward movement of the body. In the horizontal plane, particles illuminated by the xz light sheet situated approximately 3 mm below the ventral body surface were tracked within the laser light sheet for up to 40ms, indicating strong planar flow. As the peduncle decelerates, the most posterior finlet is frequently at an angle of attack of at least 20° to the incident flow, but this orientation does not result in thrust production from lift generation. Finlet 5 does redirect cross-peduncular flow and probably generates small vortices undetectable in this study. These data are the first direct demonstration that the finlets have a hydrodynamic effect on local flow during steady swimming.

Digital Scanned Laser Light Sheet Fluorescence Microscopy

2010 ◽  
Vol 2010 (5) ◽  
pp. pdb.top78-pdb.top78 ◽  
Author(s):  
P. J. Keller ◽  
E. H. K. Stelzer
Keyword(s):  
Fluorescence Microscopy ◽  
Laser Light ◽  
Light Sheet ◽  
Laser Light Sheet ◽  
Light Sheet Fluorescence Microscopy

Impact of mismatched and misaligned laser light sheet profiles on PIV performance

2017 ◽  
Vol 59 (1) ◽  
Author(s):  
K. Grayson ◽  
C. M. de Silva ◽  
N. Hutchins ◽  
I. Marusic
Keyword(s):  
Laser Light ◽  
Light Sheet ◽  
Laser Light Sheet

scholarly journals Thin laser light sheet microscope for microbial oceanography

2002 ◽  
Vol 10 (2) ◽  
pp. 145 ◽  
Author(s):  
Eran Fuchs ◽  
Jules Jaffe ◽  
Richard Long ◽  
Farooq Azam
Keyword(s):  
Laser Light ◽  
Light Sheet ◽  
Laser Light Sheet ◽  
Microbial Oceanography

Analysis of Interior Airflow in a Full-Scale Passenger-Compartment Model Using a Laser-Light-Sheet Method

1992 ◽  
Author(s):  
Yuji Ishihara ◽  
Minoru Shibata ◽  
Hiroshi Hoshino ◽  
Junichiro Hara ◽  
Kyoji Kamemoto
Keyword(s):  
Laser Light ◽  
Compartment Model ◽  
Light Sheet ◽  
Full Scale ◽  
Laser Light Sheet ◽  
Passenger Compartment

scholarly journals A Flow Visualization Study of Spore Release Using a Wind Tunnel-Mounted Laser Light Sheet

Plant Disease ◽  
1997 ◽  
Vol 81 (9) ◽  
pp. 1057-1065 ◽  
Author(s):  
J. M. Davis ◽  
A. D. Eisner ◽  
R. W. Wiener ◽  
C. E. Main
Keyword(s):  
Wind Tunnel ◽  
Laser Light ◽  
Stability Boundary ◽  
Wind Tunnel Test ◽  
Light Sheet ◽  
Diseased Plant ◽  
Neutral Stability ◽  
Laser Light Sheet ◽  
Spore Release ◽  
The Individual

A phase Doppler anemometry system in combination with a laser light sheet was used in a low-speed recirculating wind tunnel to examine the flow field around an individual leaf. Turbulence similar to that encountered near the surface of the earth in a neutral stability boundary layer was generated using a grid at the upwind end of the wind tunnel test section. Individual healthy and diseased plant leaves were introduced into the tunnel with the leaf tip pointing downwind. The Mie-scattered radiation from the spores departing the diseased leaf was captured on videotape. Image processing software was used to enhance the visual quality of the individual frames from the videotape and to make spore velocity calculations. Three main vortex regions around the leaf were identified. The importance of these regions to the separation of the spores from the leaf surface and their subsequent downwind movement was analyzed.

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