Dynamics and Optics of Bubble Tracking Velocimetry for Airflow Measurement

2007 ◽  
Author(s):  
Tetsushi Kanda ◽  
Yuichi Murai ◽  
Yuji Tasaka ◽  
Yasushi Takeda
Keyword(s):  
Relative Velocity ◽  
Particle Tracking Velocimetry ◽  
Cross Correlation ◽  
Fine Particles ◽  
Translational Motion ◽  
Basic Research ◽  
Velocity Vector Field ◽  
Large Spatial Scale ◽  
Soap Bubbles ◽  
Quantitative Visualization

Availability of particle tracking velocimetry (PTV) that is applied to movie images of soap bubbles in airflow is investigated experimentally. This study is positioned as a basic research for measuring environmental flow with a large spatial scale, such as flows around building, trees, and near-ground airflow boundary layer. Instead of solid fine particles, soap bubbles are used as the airflow tracer for reducing environmental impact. Typical bubble size provided by the present bubble generator is controlled around 20mm, at which the bubbles obviously have relative velocity to the airflow. We report three topics on the bubble tracking velocimetry (BTV) in this paper: 1) optics of bubble-imaging for quantitative visualization, and application to 3-D visualization using color illumination, 2) theoretical estimation of bubble’s relative velocity to airflow based on an equation of bubble’s translational motion, 3) comparison of velocity vector field obtained by the BTV with that from cross-correlation PIV applied for smoke image. For the latter two topics, airflow around a NACA airfoil is chosen as the target of BTV measurement since it causes significant slip motion of soap bubbles from the airflow that accompanies shear rate, convective acceleration, pressure gradient, and separation.

The motion of rotating cylinders sliding on pebbled ice

2000 ◽  
Vol 77 (11) ◽  
pp. 847-862 ◽  
Author(s):  
MRA Shegelski ◽  
M Reid ◽  
R Niebergall
Keyword(s):  
Thin Film ◽  
Liquid Film ◽  
Contact Area ◽  
Relative Velocity ◽  
Thin Liquid Film ◽  
Center Of Mass ◽  
Translational Motion ◽  
Rotating Cylinder ◽  
Outer Edge ◽  
Slow Rotation

We consider the motion of a cylinder with the same mass and sizeas a curling rock, but with a very different contact geometry.Whereas the contact area of a curling rock is a thin annulus havinga radius of 6.25 cm and width of about 4 mm, the contact area of the cylinderinvestigated takes the form of several linear segments regularly spacedaround the outer edge of the cylinder, directed radially outward from the center,with length 2 cm and width 4 mm. We consider the motion of this cylinderas it rotates and slides over ice having the nature of the ice surfaceused in the sport of curling. We have previously presented a physicalmodel that accounts for the motion of curling rocks; we extend this modelto explain the motion of the cylinder under investigation. In particular,we focus on slow rotation, i.e., the rotational speed of the contact areasof the cylinder about the center of mass is small compared to thetranslational speed of the center of mass.The principal features of the model are (i) that the kineticfriction induces melting of the ice, with the consequence that thereexists a thin film of liquid water lying between the contact areasof the cylinder and the ice; (ii) that the radial segmentsdrag some of the thin liquid film around the cylinder as it rotates,with the consequence that the relative velocity between the cylinderand the thin liquid film is significantly different than the relativevelocity between the cylinder and the underlying solid ice surface.Since it is the former relative velocity that dictates the nature of themotion of the cylinder, our model predicts, and observations confirm, thatsuch a slowly rotating cylinder stops rotating well before translationalmotion ceases. This is in sharp contrast to the usual case of most slowlyrotating cylinders, where both rotational and translational motion ceaseat the same instant. We have verified this prediction of our model bycareful comparison to the actual motion of a cylinder having a contactarea as described.PACS Nos.: 46.00, 01.80+b

A Simulation Study on Translational Piston Air Compressor

2011 ◽  
Vol 328-330 ◽  
pp. 628-632
Author(s):  
Kui Hua Geng ◽  
Meng Tang ◽  
Hong Dong Yu ◽  
Ai Nong Geng ◽  
Shi Guang Du
Keyword(s):  
Simulation Study ◽  
Relative Velocity ◽  
Friction And Wear ◽  
Kinetic Characteristic ◽  
Translational Motion ◽  
Piston Compressor ◽  
Working Principle ◽  
Rolling Piston ◽  
Rotary Speed ◽  
Conventional Rolling

The structure and working principle of a new translational piston compressor was introduced in this paper. Its piston works in a way of translational motion, hence reduces the piston’s relative velocity to cylinder and cap, as well as friction and wear. In order to avoid vane detaching from piston, simulations were carried out regarding the pre-tightening spring and an optimal preload of the spring was obtained. By analyzed and compared to conventional rolling piston compressor in term of contact force between vane and piston, it was pointed out that the new compressor possessed advantage of kinetic characteristic and is more suitable for the situation of high rotary speed.

scholarly journals The Motion of Rapidly Rotating Curling Rocks

1999 ◽  
Vol 52 (6) ◽  
pp. 1025 ◽  
Author(s):  
Mark R. A. Shegelski ◽  
Ross Niebergall
Keyword(s):  
Liquid Film ◽  
Relative Velocity ◽  
Thin Liquid Film ◽  
Translational Motion ◽  
Slow Rotation ◽  
Kinetic Friction ◽  
Centre Of Mass ◽  
Ice Surface ◽  
Translational Speed ◽  
Careful Comparison

We present a physical model that accounts for the motion of rapidly rotating curling rocks. By rapidly rotating we mean that the rotational speed of the contact annulus of the rock about the centre of mass is large compared with the translational speed of the centre of mass. The principal features of the model are: (i ) that the kinetic friction induces melting of the ice, with the consequence that there exists a thin film of liquid water lying between the contact annulus of the rock and the ice; (ii ) that the curling rock drags some of the thin liquid film around the rock as it rotates, with the consequence that the relative velocity between the rock and the thin liquid film is significantly different to the relative velocity between the rock and the underlying solid ice surface. Since it is the former relative velocity which dictates the nature of the motion of the curling rock, our model predicts some interesting differences between the motions of slowly versus rapidly rotating rocks. Of principal note is that our model predicts, and observations confirm, that rapidly rotating curling rocks stop moving translationally well before rotational motion ceases. This is in sharp contrast to the usual case of slow rotation, where both rotational and translational motion cease at the same instant. We have verified this and other predictions of our model by careful comparison with the motion of actual curling rocks.

scholarly journals In-Depth Investigation of Statistical and Physicochemical Properties on the Field Study of the Intermittent Filling of Large Water Tanks

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Do-Hwan Kim ◽  
Doo Yong Choi ◽  
Taeho Choi ◽  
Zong Woo Geem
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Field Measurement ◽  
Cross Correlation ◽  
Fine Particles ◽  
Normal Operation ◽  
Particle Count ◽  
Power Spectral ◽  
Flow Pressure ◽  
Water Tanks

Large-demand customers, generally high-density dwellings and buildings, have dedicated ground or elevated water tanks to consistently supply drinking water to residents. Online field measurement for Nonsan-2 district meter area demonstrated that intermittent replenishment from large-demand customers could disrupt the normal operation of a water distribution system by taking large quantities of water in short times when filling the tanks from distribution mains. Based on the previous results of field measurement for hydraulic and water quality parameters, statistical analysis is performed for measured data in terms of autocorrelation, power spectral density, and cross-correlation. The statistical results show that the intermittent filling interval of 6.7 h and diurnal demand pattern of 23.3 h are detected through autocorrelation analyses, the similarities of the flow-pressure and the turbidity-particle count data are confirmed as a function of frequency through power spectral density analyses, and a strong cross-correlation is observed in the flow-pressure and turbidity-particle count analyses. In addition, physicochemical results show that the intermittent refill of storage tank from large-demand customers induces abnormal flow and pressure fluctuations and results in transient-induced turbid flow mainly composed of fine particles ranging within 2–4 μm and constituting Fe, Si, and Al.

scholarly journals Modulated 3D Cross-Correlation Dynamic Light Scattering Applications for Optical Biosensing and Time-Dependent Monitoring of Nanoparticle-Biofluid Interactions

2020 ◽  
Vol 10 (24) ◽  
pp. 8969
Author(s):  
Silvia Schintke ◽  
Eleonora Frau
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Protein Interactions ◽  
Recent Progress ◽  
Cross Correlation ◽  
Translational Motion ◽  
Mouse Serum ◽  
Optical Biosensing ◽  
Model Protein ◽  
Protein Bovine Serum Albumin

This paper reviews dynamic light scattering (DLS) of gold nanoparticle-protein interactions for the model protein bovine serum albumin (BSA), as well as in complex biofluids, at the example of mouse serum. DLS data of nanorods of various aspect ratio, of proteins and of mouse serum are discussed in terms of the analysis of their hydrodynamic radii, leading to the distinction of rotational and translational motion as well as to the detection of agglomerates. We address in particular advances obtained by modulated 3D cross correlation dynamic light scattering and recent progress using the CORENN algorithm for analysis of DLS data.

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