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

2020 ◽  
Author(s):  
Michael Benson ◽  
Daniel Chung ◽  
Gabriel Fuhrman ◽  
David Helmer ◽  
Ty Homan ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Fluid Velocity ◽  
Water Channel ◽  
Three Dimensional ◽  
Central Business District ◽  
Field Measurements ◽  
Oklahoma City ◽  
Scaled Model ◽  
Full Field ◽  
City Model

Abstract Motivated by the Joint Urban 2003 field project and subsequent studies, magnetic resonance imaging (MRI) techniques were used to collect full-field measurements of three-dimensional fluid velocity and concentration across a scaled model of 2003 Oklahoma City. The study was intended to develop, test, and demonstrate a repeatable puff release with MRI compatible equipment. In order to accomplish this, a contaminant was injected through the floor of a city model in discrete puffs using a solenoid valve. Sealed to fit inside a water channel, the 1:2,206 scale city model covered the central business district of the city as it was in 2003. The main flow was fully turbulent with a Reynolds number of 36,000, while vertical puff injection occurred at a Reynolds number of 2,642. Using MRV and MRC methods, the three components of velocity and concentration were measured at more than 2 million locations for each of the 12 phases of the injection period. MRV measurements examined the fluid flow with respect to building geometry. Collected at heights corresponding to this MRV data, MRC measurements enabled the analysis of the vertical and lateral dispersion of the contaminant. Ultimately, the study demonstrated a novel MRI technique through contaminant puff release and can be used for the validation of urban contaminant dispersion models.

scholarly journals Population Distribution in the Wake of a Sphere

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1498 ◽  
Author(s):  
Taraprasad Bhowmick ◽  
Yong Wang ◽  
Michele Iovieno ◽  
Gholamhossein Bagheri ◽  
Eberhard Bodenschatz
Keyword(s):  
Reynolds Number ◽  
Spatial Distribution ◽  
Population Density ◽  
Density Distribution ◽  
Population Distribution ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Wake Flow ◽  
Sample Number ◽  
Scalar Fluxes

The physics of heat and mass transfer from an object in its wake has significant importance in natural phenomena as well as across many engineering applications. Here, we report numerical results on the population density of the spatial distribution of fluid velocity, pressure, scalar concentration, and scalar fluxes of a wake flow past a sphere in the steady wake regime (Reynolds number 25 to 285). Our findings show that the spatial population distributions of the fluid and the transported scalar quantities in the wake follow a Cauchy-Lorentz or Lorentzian trend, indicating a variation in its sample number density inversely proportional to the squared of its magnitude. We observe this universal form of population distribution both in the symmetric wake regime and in the more complex three dimensional wake structure of the steady oblique regime with Reynolds number larger than 225. The population density distribution identifies the increase in dimensionless kinetic energy and scalar fluxes with the increase in Reynolds number, whereas the dimensionless scalar population density shows negligible variation with the Reynolds number. Descriptive statistics in the form of population density distribution of the spatial distribution of the fluid velocity and the transported scalar quantities is important for understanding the transport and local reaction processes in specific regions of the wake, which can be used e.g., for understanding the microphysics of cloud droplets and aerosol interactions, or in the technical flows where droplets interact physically or chemically with the environment.

Fluid Flow and Lateral Fluid Dispersion in Bounded Granular Beds

2002 ◽  
Author(s):  
Azita Soleymani ◽  
Eveliina Takasuo ◽  
Piroz Zamankhan ◽  
William Polashenski
Keyword(s):  
Reynolds Number ◽  
Porous Media ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Numerical Results ◽  
Transition To Turbulence ◽  
Wide Range

Results are presented from a numerical study examining the flow of a viscous, incompressible fluid through random packing of nonoverlapping spheres at moderate Reynolds numbers (based on pore permeability and interstitial fluid velocity), spanning a wide range of flow conditions for porous media. By using a laminar model including inertial terms and assuming rough walls, numerical solutions of the Navier-Stokes equations in three-dimensional porous packed beds resulted in dimensionless pressure drops in excellent agreement with those reported in a previous study (Fand et al., 1987). This observation suggests that no transition to turbulence could occur in the range of Reynolds number studied. For flows in the Forchheimer regime, numerical results are presented of the lateral dispersivity of solute continuously injected into a three-dimensional bounded granular bed at moderate Peclet numbers. Lateral fluid dispersion coefficients are calculated by comparing the concentration profiles obtained from numerical and analytical methods. Comparing the present numerical results with data available in the literature, no evidence has been found to support the speculations by others for a transition from laminar to turbulent regimes in porous media at a critical Reynolds number.

An Infrared Interferometer for Elastoplastic Crack-Tip Field Investigation of Homogeneous and Bimaterial Beams: A Study of Three-Dimensional Effects and J-Dominance

1998 ◽  
Vol 65 (4) ◽  
pp. 1032-1041
Author(s):  
J. K. Sinha ◽  
H. V. Tippur
Keyword(s):  
Plane Deformation ◽  
Three Dimensional ◽  
Surface Preparation ◽  
Field Measurements ◽  
Sample Surface ◽  
Field Investigation ◽  
Crack Tip Field ◽  
Full Field ◽  
Infrared Wavelength ◽  
Dimensional Effects

An infrared interferometer capable of performing real-time full-field noncontacting deformation field measurements on optically rough surfaces is proposed as a tool for elastoplastic fracture mechanics investigations. The choice of the infrared wavelength allows interferometric measurements on fracture samples with little or no surface preparation and is more tolerant of the damage accumulation near the crack. The interferometer also bridges a sensitivity gap among existing techniques for out-of-plane deformation measurement. First, a rigorous Fourier optics analysis is provided for the interferometer and the range of surface roughness that can be studied using this interferometer is examined. The interferometer is then used for mapping deformations near elastoplastically deformed cracks in aluminum beams and solder-copper bimaterials. The regions of dominant three-dimensional effects and J-dominance are examined on the sample surface by evaluating measurements along with companion finite element analyses and the HRR fields.

scholarly journals An open-source tool for the validation of finite element models using three-dimensional full-field measurements

2020 ◽  
Vol 77 ◽  
pp. 125-129
Author(s):  
Alexander Abel ◽  
Stephanie L. Kahmann ◽  
Stephen Mellon ◽  
Manfred Staat ◽  
Alexander Jung
Keyword(s):  
Finite Element ◽  
Open Source ◽  
Three Dimensional ◽  
Field Measurements ◽  
Finite Element Models ◽  
Full Field ◽  
Open Source Tool

Oklahoma City Contaminant Dispersion: Concentration Data Processing and Analysis for a Scaled Puff Release Experiment

2020 ◽  
Author(s):  
Ty Homan
Keyword(s):  
Magnetic Resonance ◽  
Preliminary Investigation ◽  
Water Channel ◽  
Concentration Field ◽  
Oklahoma City ◽  
Concentration Data ◽  
Scaled Model ◽  
Data Set ◽  
Processing Methods ◽  
Contaminant Dispersion

Abstract Magnetic resonance techniques were leveraged to obtain velocity and concentration measurements for a puff release contaminant dispersion study. The study involved a scaled model of downtown Oklahoma City as it was in 2003, and sought to provide a high fidelity, three-dimensional data set for comparison with JU2003 and subsequent studies. The scaled model was placed in a water channel with fully turbulent flow (Re = 36,000), and an MRI system was used to take scans at 12 time-specific measurement phases throughout the puff injection cycle. The present work details processing methods applied to the nearly 650 million magnetic resonance concentration (MRC) data points obtained from the study. Processing entailed the calculation of a concentration field through background subtraction and normalization involving several distinct scan types. Uncertainty was reduced through the scaling and combination of high molarity scans. Processing methods are followed by a preliminary investigation of the results, which highlights noteworthy elements of scalar transport within the data set and the need for further investigation of the complex flow field. The study ultimately demonstrates the applicability of magnetic resonance techniques to puff release and dynamic experimental conditions, as well as a method for working with data from phase-locked experiments.

scholarly journals Three-Dimensional Velocity Measurements Around and Downstream of a Rotating Vertical Axis Wind Turbine

2014 ◽  
Author(s):  
Kevin J. Ryan ◽  
Filippo Coletti ◽  
John O. Dabiri ◽  
John K. Eaton
Keyword(s):  
Reynolds Number ◽  
Wind Turbines ◽  
Wind Farm ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Mean Velocity ◽  
Scaled Model ◽  
Recirculation Bubble ◽  
Power Extraction ◽  
Turbulent Reynolds Number

Modern designs for straight-bladed vertical axis wind turbines (VAWTs) feature smaller individual footprints than conventional horizontal axis wind turbines (HAWTs), allowing closer spacing of turbines and potentially greater power extraction for the same wind farm footprint. However, the wakes of up-stream turbines could persist far enough to affect the performance of closely-spaced downstream turbines. In order to optimize the inter-turbine spacing and to investigate the potential for constructive aerodynamic interactions, the complex dynamics of VAWT wakes should be understood. The full three-component mean velocity field around and downstream of a scaled model of a rotating VAWT has been measured by Magnetic Resonance Velocimetry (MRV). The model turbine has an aspect ratio (height/diameter) of 1, and was operated in a water facility at subscale but still turbulent Reynolds number of 11,600 based on the turbine diameter. The main flow features including recirculation bubble sizes and strong vortex structures are believed to be representative of flow at full scale Reynolds number. To have kinematic similarity with a power-producing turbine, the model turbine was externally driven. Measurements were taken with the turbine stationary and while driven at tip speed ratios (TSRs) of 1.25 and 2.5, realistic values for VAWTs in operation. The MRV measurement produced three-dimensional velocity data with a resolution of 1/50 of the turbine diameter in all three directions. The flow is shown to be highly three dimensional and asymmetric for the entirety of the investigated region (up to 7 diameters downstream of the turbine). The higher TSR produced greater velocity defect and asymmetry in the near wake behind the turbine, but also showed faster wake recovery than the slower TSR and stationary cases. Wake recovery is affected by a counter-rotating vortex pair generated at the upwind-turning side of the turbine, which mixes faster fluid from the freestream in with the wake. The strength of vortices is shown to increase with TSR.

Onset of Transition in the Flow Over a Three-Dimensional Array of Rectangular Obstacles

1992 ◽  
Vol 114 (2) ◽  
pp. 251-255 ◽  
Author(s):  
S. V. Garimella ◽  
P. A. Eibeck
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Water Channel ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Channel Height ◽  
Circuit Boards ◽  
Three Dimensional Flow ◽  
Transfer Data ◽  
Array Geometry

Onset of transition is investigated in the flow over an array of protruding elements mounted on the bottom wall of a rectangular water channel simulating flow passages between adjacent circuit boards in computers. The element dimensions are held constant while the channel height and the element spacing are varied. Flow visualization and turbulence measurements are used to determine transition Reynolds numbers, which compare well with previous results obtained from heat transfer data. The complicated, three-dimensional flow field causes transition to be a function not only of flow rate and array geometry but also of location in the array. Transition occurs in the fully developed region of the array at a channel height-based Reynolds number of 700 for a channel height of 1.2 element heights, increasing to 1900 for a channel height of 3.6 element heights. However, when Reynolds number is defined based on element height, transition occurs at the same Reynolds number of 550 for all channel heights. Increasing the stream wise spacing between elements causes transition to occur at lower Reynolds numbers.

scholarly journals Three-Dimensional Flow Field Measurements in a Transonic Turbine Cascade

1996 ◽  
Author(s):  
P. W. Giel ◽  
D. R. Thurman ◽  
I. Lopez ◽  
R. J. Boyle ◽  
G. J. Van Fossen ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Flow Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Field Measurements ◽  
Three Dimensional Flow ◽  
Blade Cascade ◽  
Transonic Turbine ◽  
Exit Mach Number

Three-dimensional flow field measurements are presented for a large scale transonic turbine blade cascade. Flow field total pressures and pitch and yaw flow angles were measured at an inlet Reynolds number of 1.0 × 106 and at an isentropic exit Mach number of 1.3 in a low turbulence environment. Flow field data was obtained on five pitchwise/spanwise measurement planes, two upstream and three downstream of the cascade, each covering three blade pitches. Three-hole boundary layer probes and five-hole pitch/yaw probes were used to obtain data at over 1200 locations in each of the measurement planes. Blade and endwall static pressures were also measured at an inlet Reynolds number of 0.5 × 106 and at an isentropic exit Mach number of 1.0. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136° of turning and an axial chord of 12.7 cm. The flow field in the cascade is highly three-dimensional as a result of thick boundary layers at the test section inlet and because of the high degree of flow turning. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for CFD code and model verification.

scholarly journals Vortex interaction on a LEX configuration

2021 ◽  
Author(s):  
Moo-Ting Chou ◽  
Jiun-Jih Miau ◽  
Li-Yu Chen
Keyword(s):  
Reynolds Number ◽  
Water Channel ◽  
Three Dimensional ◽  
Leading Edge ◽  
Quantitative Information ◽  
Extension Model ◽  
Image Velocimetry ◽  
Visualization Experiments ◽  
Low Speed Wind Tunnel ◽  
Edge Extension

AbstractFlow visualization experiments were conducted in a water channel and a low-speed wind tunnel at Reynolds number of 1.54 $$\times$$ × 104 to 1.2 $$\times$$ × 105 for a leading-edge extension model, which is referred to as a NASA TP-1803 model in this study. In addition, particle image velocimetry velocity measurements were taken in the water channel to obtain the quantitative information about the three-dimensional velocity field over the strake and wing surfaces. The results obtained at low, medium and high angles of attacks represent three distinct cases of interaction between the strake and wing vortices. Namely, at α = 5o and 10° the strake and wing vortices were developed over the wing surface without significant interaction noticed; at α = 20°, the strake vortex strongly interacted with the wing vortex in an intertwining manner, which was sensitive to Reynolds number; at α = 30°, the breakdown of the strake vortex took place close to the junction of the strake and the wing; thus, the interaction of the strake and the wing vortices appeared to be less significant than the case of α = 20°. Graphic abstract

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