Three-dimensional velocity measurements in a roughness sublayer using microscopic digital in-line holography and optical index matching

2012 ◽  
Vol 24 (2) ◽  
pp. 024004 ◽  
Author(s):  
Siddharth Talapatra ◽  
Joseph Katz
Keyword(s):  
Three Dimensional ◽  
Roughness Sublayer ◽  
Velocity Measurements ◽  
Optical Index ◽  
Index Matching

Operational Model and its Validation with Drift Tests in Water Areas Around the Baltic Sea

1994 ◽  
Vol 29 (2-3) ◽  
pp. 293-308
Author(s):  
J. Koponen ◽  
M. Virtanen ◽  
H. Vepsä ◽  
E. Alasaarela
Keyword(s):  
Three Dimensional ◽  
Fast Response ◽  
Velocity Measurements ◽  
Short Term ◽  
Large Lakes ◽  
Operational Model ◽  
Water Currents ◽  
Emergency Situations ◽  
Sensitivity Tests ◽  
The Baltic

Abstract Three-dimensional (3-D) mathematical models of water currents, transport, mixing, reaction kinetic, and interactions with bottom and air have been used in Finland regularly since 1982 and applied to about 40 cases in large lakes, inland seas and their coastal waters. In each case, model validity has been carefully tested with available flow velocity measurements, tracer studies and water quality observations. For operational use, i.e., for spill combatting and sea rescue, the models need fast response, proven validity and illustrative visualization. In 1987-90, validated models were implemented for operational use at five sea areas along the Finnish coast. Further validation was obtained in model applications from nine documented or arranged cases and from seven emergency situations. Sensitivity tests supplement short-term validation. In the Bothnian Sea, it was nescessary to start the calculation of water currents three days prior to the start of the experiment to reduce initial inaccuracies and to make the coastal transport estimates meaningful.

The two-sided lid-driven cavity: experiments on stationary and time-dependent flows

2002 ◽  
Vol 450 ◽  
pp. 67-95 ◽  
Author(s):  
CH. BLOHM ◽  
H. C. KUHLMANN
Keyword(s):  
Three Dimensional ◽  
Standing Waves ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Flow State ◽  
Incompressible Fluid Flow ◽  
Velocity Measurements ◽  
Driven Cavity ◽  
Rectangular Container ◽  
Hot Film

The incompressible fluid flow in a rectangular container driven by two facing sidewalls which move steadily in anti-parallel directions is investigated experimentally for Reynolds numbers up to 1200. The moving sidewalls are realized by two rotating cylinders of large radii tightly closing the cavity. The distance between the moving walls relative to the height of the cavity (aspect ratio) is Γ = 1.96. Laser-Doppler and hot-film techniques are employed to measure steady and time-dependent vortex flows. Beyond a first threshold robust, steady, three-dimensional cells bifurcate supercritically out of the basic flow state. Through a further instability the cellular flow becomes unstable to oscillations in the form of standing waves with the same wavelength as the underlying cellular flow. If both sidewalls move with the same velocity (symmetrical driving), the oscillatory instability is found to be tricritical. The dependence on two sidewall Reynolds numbers of the ranges of existence of steady and oscillatory cellular flows is explored. Flow symmetries and quantitative velocity measurements are presented for representative cases.

Three-Dimensional Concentration and Velocity Measurements of a Pulsatile Contaminant Release in a Model of Oklahoma City

2021 ◽  
Author(s):  
Daniel Chung ◽  
Lynne Mooradian ◽  
Joshua Rhee ◽  
Michael Benson ◽  
Christopher J. Elkins ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Oklahoma City ◽  
Velocity Measurements ◽  
Contaminant Release

Three-dimensional velocity measurements around bridge piers in gravel bed

2017 ◽  
Vol 36 (6) ◽  
pp. 663-676 ◽  
Author(s):  
Manish Pandey ◽  
P. K. Sharma ◽  
Z. Ahmad ◽  
Umesh Kumar Singh ◽  
Nilav Karna
Keyword(s):  
Three Dimensional ◽  
Bridge Piers ◽  
Velocity Measurements ◽  
Gravel Bed

scholarly journals Calculation of acoustic flow-rate measurements error with the help of Fermat’s principle

2018 ◽  
Vol 211 ◽  
pp. 04007
Author(s):  
Alexander Petrov ◽  
Semyon Shkundin
Keyword(s):  
Control Systems ◽  
Cross Section ◽  
Flow Rate ◽  
Three Dimensional ◽  
Air Flow Rate ◽  
Velocity Measurements ◽  
Three Dimensional Flow ◽  
Automatic Control Systems ◽  
A Value ◽  
Flow Changes

The establishment of dispatching and automatic control systems for mine ventilation is impossible without the availability of perfect air flow rate sensors. Existing anemometers (tachometer, heat) do not meet these requirements. The error of average in cross section velocity measurements with such sensors reaches 15-20, sometimes 30%. The reason - the speed measured at one point is interpreted as the average over the cross section. The reliability of the sensors is small, because they are exposed to the damaging effect of a dusty atmosphere. Stationary installed anemometers clutter cross section, which is not always allowed. Fermat’s variational principle is used for derivation of the formula for the time of propagation of a sonic signal between two set points A and B in a steady three-dimensional flow of a fluid or gas. It is shown that the fluid flow changes the time of signal reception by a value proportional to the flow rate independently of the velocity profile. The time difference in the reception of the signals from point B to point A and vice versa is proportional with a high accuracy to the flow rate. It is shown that the relative error of the formula does not exceed the square of the largest Mach number. This makes it possible to measure the flow rate of a fluid or gas with an arbitrary steady subsonic velocity field

Separating and Reattaching Flow Structure in a Suddenly Expanding Rectangular Duct

1995 ◽  
Vol 117 (1) ◽  
pp. 17-23 ◽  
Author(s):  
G. Papadopoulos ◽  
M. V. O¨tu¨gen
Keyword(s):  
Aspect Ratio ◽  
Flow Structure ◽  
Three Dimensional ◽  
Side Wall ◽  
Stream Velocity ◽  
Rectangular Duct ◽  
Mean Flow ◽  
Wall Effects ◽  
Velocity Measurements ◽  
Aspect Ratios

The incompressible turbulent flow over a backward-facing step in a rectangular duct was investigated experimentally. The side wall effects on the core flow were determined by varying the aspect ratio (defined as the step span-to-height ratio) from 1 to 28. The Reynolds number, based on the step height and the oncoming free-stream velocity, was 26,500. Detailed velocity measurements were made, including the turbulent stresses, in a region which extended past the flow reattachment zone. Wall static pressure was also measured on both the step and flat walls. In addition, surface visualizations were obtained on all four walls surrounding the separated flow to supplement near-wall velocity measurements. The results show that the aspect ratio has an influence on both the velocity and wall pressure even for relatively large aspect ratios. For example, in the redevelopment region downstream of reattachment, the recovery pressure decreases with smaller aspect ratios. The three-dimensional side wall effects tend to slow down the relaxation downstream of reattachment for smaller aspect ratios as evidenced by the evolution of the velocity field. For the two smallest aspect ratios investigated, higher centerplane streamwise and transverse velocities were obtained which indicate a three-dimensional mean flow structure along the full span of the duct.

A matching pursuit approach to solenoidal filtering of three-dimensional velocity measurements

2014 ◽  
Vol 263 ◽  
pp. 206-221 ◽  
Author(s):  
Daniele Schiavazzi ◽  
Filippo Coletti ◽  
Gianluca Iaccarino ◽  
John K. Eaton
Keyword(s):  
Matching Pursuit ◽  
Three Dimensional ◽  
Velocity Measurements

scholarly journals Three-Dimensional Analysis of Flow Velocities through a Large Pool Fish Pass in the Trzebuńka Stream

Proceedings ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 59
Author(s):  
Kamil Suder ◽  
Karol Plesiński ◽  
Artur Radecki-Pawlik
Keyword(s):  
Three Dimensional ◽  
Fish Passage ◽  
Point Of View ◽  
Shear Stresses ◽  
Velocity Measurements ◽  
Water Flow Velocity ◽  
Hydrodynamic Parameters ◽  
Fish Pass ◽  
Large Pool ◽  
Parameter Values

This paper presents the hydrodynamic parameter values of a large pool fish pass joined with block ramps in the Trzebuńka stream. The aim of this work is to evaluate the large pool fish pass patency in terms of fish and to answer the question of whether fish migration upstream is possible. The assessment of hydrodynamic parameters was carried out on the basis of water flow velocity measurements using a flow tracker device and by calculating the following parameters: Water depth, shear stresses, and Froude’s and Reynold’s numbers. Velocity measurements were carried out in 23–30 hydrometric points which were determined in each of the pools. A survey was done using the Topcon GTS-226 (Topcon Corporation, Tokyo, Japan) total station. The data were processed in order to obtain the results of hydrodynamic parameters prevailing in flowing water. The graphs were prepared using the Grapher 11 software, showing the distribution of individual hydrodynamic parameters for fish pass chambers and overflows in the fish passage. We concluded that the fish pass in Stróża was designed and constructed correctly. However, from a technical point of view, some deficiencies could be found.

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