scholarly journals A Novel One-Camera-Five-Mirror Three-Dimensional Imaging Method for Reconstructing the Cavitation Bubble Cluster in a Water Hydraulic Valve

2018 ◽  
Vol 8 (10) ◽  
pp. 1783 ◽  
Author(s):  
Haihang Wang ◽  
He Xu ◽  
Vishwanath Pooneeth ◽  
Xiao-Zhi Gao
Keyword(s):  
Cavitation Bubble ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Imaging Method ◽  
Main Approach ◽  
Robust Algorithms ◽  
Bubble Cluster ◽  
Throttle Valve ◽  
Feature Based ◽  
Hydraulic Valve

In order to study the bubble morphology, a novel experimental and numerical approach was implemented in this research focusing on the analysis of a transparent throttle valve made by Polymethylmethacrylate (PMMA) material. A feature-based algorithm was written using the MATLAB software, allowing the 2D detection and three-dimensional (3D) reconstruction of bubbles: collapsing and clustered ones. The valve core, being an important part of the throttle valve, was exposed to cavitation; hence, to distinguish it from the captured frames, the faster region-based convolutional neural network (R-CNN) algorithm was used to detect its morphology. Additionally, the main approach grouping the above listed techniques was implemented using an optimized virtual stereo vision arrangement of one camera and five plane mirrors. The results obtained during this study validated the robust algorithms and optimization applied.

Modeling and Assessment of the Produced Water Discharges from Offshore Petroleum Platforms

2007 ◽  
Vol 42 (4) ◽  
pp. 303-310 ◽  
Author(s):  
Zhi Chen ◽  
Lin Zhao ◽  
Kenneth Lee ◽  
Charles Hannath
Keyword(s):  
Random Walk ◽  
Produced Water ◽  
Model Development ◽  
Three Dimensional ◽  
Monitoring Program ◽  
Ecological Monitoring ◽  
Numerical Approach ◽  
Ocean Model ◽  
Scale Model ◽  
Water Stream

Abstract There has been a growing interest in assessing the risks to the marine environment from produced water discharges. This study describes the development of a numerical approach, POM-RW, based on an integration of the Princeton Ocean Model (POM) and a Random Walk (RW) simulation of pollutant transport. Specifically, the POM is employed to simulate local ocean currents. It provides three-dimensional hydrodynamic input to a Random Walk model focused on the dispersion of toxic components within the produced water stream on a regional spatial scale. Model development and field validation of the predicted current field and pollutant concentrations were conducted in conjunction with a water quality and ecological monitoring program for an offshore facility located on the Grand Banks of Canada. Results indicate that the POM-RW approach is useful to address environmental risks associated with the produced water discharges.

Cardiovascular Imaging for Guiding Interventional Therapy in Structural Heart Diseases

2020 ◽  
Vol 16 (2) ◽  
pp. 111-122
Author(s):  
Nora Rat ◽  
Iolanda Muntean ◽  
Diana Opincariu ◽  
Liliana Gozar ◽  
Rodica Togănel ◽  
...  
Keyword(s):  
Heart Diseases ◽  
Interventional Procedure ◽  
Imaging Techniques ◽  
Ductus Arteriosus ◽  
Three Dimensional ◽  
High Specificity ◽  
Interventional Therapy ◽  
Structural Defects ◽  
Imaging Method ◽  
Three Dimensional Echocardiography

Development of interventional methods has revolutionized the treatment of structural cardiac diseases. Given the complexity of structural interventions and the anatomical variability of various structural defects, novel imaging techniques have been implemented in the current clinical practice for guiding the interventional procedure and for selection of the device to be used. Three– dimensional echocardiography is the most used imaging method that has improved the threedimensional assessment of cardiac structures, and it has considerably reduced the cost of complications derived from malalignment of interventional devices. Assessment of cardiac structures with the use of angiography holds the advantage of providing images in real time, but it does not allow an anatomical description. Transesophageal Echocardiography (TEE) and intracardiac ultrasonography play major roles in guiding Atrial Septal Defect (ASD) or Patent Foramen Ovale (PFO) closure and device follow-up, while TEE is the procedure of choice to assess the flow in the Left Atrial Appendage (LAA) and the embolic risk associated with a decreased flow. On the other hand, contrast CT and MRI have high specificity for providing a detailed description of structure, but cannot assess the flow through the shunt or the valvular mobility. This review aims to present the role of modern imaging techniques in pre-procedural assessment and intraprocedural guiding of structural percutaneous interventions performed to close an ASD, a PFO, an LAA or a patent ductus arteriosus.

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

Simulation of small-angle scattering curves by numerical Fourier transformation

2007 ◽  
Vol 40 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Klaus Schmidt-Rohr
Keyword(s):  
Form Factor ◽  
Small Angle ◽  
Fourier Transformation ◽  
Three Dimensional ◽  
Power Laws ◽  
Numerical Approach ◽  
Peak Position ◽  
Two Dimensions ◽  
Correlation Peak ◽  
Scattering Intensity

A simple numerical approach for calculating theq-dependence of the scattering intensity in small-angle X-ray or neutron scattering (SAXS/SANS) is discussed. For a user-defined scattering density on a lattice, the scattering intensityI(q) (qis the modulus of the scattering vector) is calculated by three-dimensional (or two-dimensional) numerical Fourier transformation and spherical summation inqspace, with a simple smoothing algorithm. An exact and simple correction for continuous rather than discrete (lattice-point) scattering density is described. Applications to relatively densely packed particles in solids (e.g.nanocomposites) are shown, where correlation effects make single-particle (pure form-factor) calculations invalid. The algorithm can be applied to particles of any shape that can be defined on the chosen cubic lattice and with any size distribution, while those features pose difficulties to a traditional treatment in terms of form and structure factors. For particles of identical but potentially complex shapes, numerical calculation of the form factor is described. Long parallel rods and platelets of various cross-section shapes are particularly convenient to treat, since the calculation is reduced to two dimensions. The method is used to demonstrate that the scattering intensity from `randomly' parallel-packed long cylinders is not described by simple 1/qand 1/q4power laws, but at cylinder volume fractions of more than ∼25% includes a correlation peak. The simulations highlight that the traditional evaluation of the peak position overestimates the cylinder thickness by a factor of ∼1.5. It is also shown that a mix of various relatively densely packed long boards can produceI(q) ≃ 1/q, usually observed for rod-shaped particles, without a correlation peak.

scholarly journals Modelling of Applied Magnetic Field and Thermal Radiations Due to the Stretching of Cylinder

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1077
Author(s):  
Muhammad Tamoor ◽  
Muhammad Kamran ◽  
Sadique Rehman ◽  
Aamir Farooq ◽  
Rewayat Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Skin Friction Coefficient ◽  
Physical Parameters ◽  
Boundary Layer Equations ◽  
Convective Parameter ◽  
Momentum And Heat Transfer ◽  
Dimensional Boundary

In this study, a numerical approach was adopted in order to explore the analysis of magneto fluid in the presence of thermal radiation combined with mixed convective and slip conditions. Using the similarity transformation, the axisymmetric three-dimensional boundary layer equations were reduced to a self-similar form. The shooting technique, combined with the Range–Kutta–Fehlberg method, was used to solve the resulting coupled nonlinear momentum and heat transfer equations numerically. When physically interpreting the data, some important observations were made. The novelty of the present study lies in finding help to control the rate of heat transfer and fluid velocity in any industrial manufacturing processes (such as the cooling of metallic plates). The numerical results revealed that the Nusselt number decrease for larger Prandtl number, curvature, and convective parameters. At the same time, the skin friction coefficient was enhanced with an increase in both slip velocity and convective parameter. The effect of emerging physical parameters on velocity and temperature profiles for a nonlinear stretching cylinder has been thoroughly studied and analyzed using plotted graphs and tables.

scholarly journals A Numerically Supported Investigation of the 3D Flow in Centrifugal Impellers: Part I — The Validation Base

1996 ◽  
Author(s):  
Ch. Hirsch ◽  
S. Kang ◽  
G. Pointel
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Boundary Layer Separation ◽  
Numerical Approach ◽  
Secondary Flows ◽  
Pump Impeller ◽  
High Loss ◽  
Leakage Flows ◽  
Fine Mesh ◽  
Radial Pump

The three-dimensional flow in centrifugal impellers is investigated on the basis of a detailed analysis of the results of numerical simulations. In order to gain confidence in this process, an in-depth validation is performed, based on computations of Krain’s centrifugal compressor and of a radial pump impeller, both with vaneless diffusers. Detailed comparisons with available experimental data provide high confidence in the numerical tools and results. The appearance of a high loss ‘wake’ region results from the transport of boundary layer material from the blade surfaces to the shroud region and its location depends on the balance between secondary and tip leakage flows and is not necessarily connected to 3D boundary layer separation. Although the low momentum spots near the shroud can interfere with 3D separated regions, the main outcome of the present analysis is that these are two distinct phenomena. Part I of this paper focuses on the validation base of the numerical approach, based on fine mesh simulations, while Part II presents an analysis of the different contributions to the secondary flows and attempts to estimate their effect on the overall flow pattern.

Positron Emission Tomography (PET) for Flow Measurement

2011 ◽  
Vol 301-303 ◽  
pp. 1316-1321 ◽  
Author(s):  
Arthur E. Ruggles ◽  
Bi Yao Zhang ◽  
Spero M. Peters
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Three Dimensional ◽  
Bulk Water ◽  
Emission Tomography ◽  
Optical Methods ◽  
Imaging Method ◽  
Analysis And Design ◽  
Pet Tracer ◽  
Positron Emission

Positron Emission Tomography (PET) produces a three dimensional spatial distribution of positron-electron annihilations within an image volume. Various positron emitters are available for use in aqueous, organic and liquid metal flows. Preliminary experiments at the University of Tennessee at Knoxville (UTK) injected small flows of PET tracer into a bulk water flow in a four rod bundle. The trajectory and diffusion of the tracer in the bulk flow were then mapped using a PET scanner. A spatial resolution of 1.4 mm is achieved with current preclinical Micro-PET imaging equipment resulting in 200 MB 3D activity fields. A time resolved 3-D spatial activity profile was also measured. The PET imaging method is especially well suited to complex geometries where traditional optical methods such as LDV and PIV are difficult to apply. PET methods are uniquely useful for imaging in opaque fluids, opaque pressure boundaries, and multiphase studies. Several commercial and shareware Computational Fluid Dynamics (CFD) codes are currently used for science and engineering analysis and design. These codes produce detailed three dimensional flow predictions. The models produced by these codes are often difficult to validate. The development of this experimental technique offers a modality for the comparison of CFD outcomes with experimental data. Developed data sets from PET can be used in verification and validation exercises of simulation outcomes.

scholarly journals A feature-based mesh adaptation for the unsteady high speed compressible flows in complex three-dimensional domains

2016 ◽  
Vol 40 (3) ◽  
pp. 1728-1740
Author(s):  
Hoang-Huy Nguyen ◽  
Vinh-Tan Nguyen ◽  
Matthew A. Price ◽  
Oubay Hassan
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Three Dimensional ◽  
Mesh Adaptation ◽  
Feature Based

Thermal jet drilling of granite rock: a numerical 3D finite-element study

2021 ◽  
Vol 379 (2196) ◽  
pp. 20200128
Author(s):  
Timo Saksala ◽  
Reijo Kouhia ◽  
Ahmad Mardoukhi ◽  
Mikko Hokka
Keyword(s):  
Finite Elements ◽  
Numerical Study ◽  
Thermal Flux ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Mass Scaling ◽  
Granite Rock ◽  
Fracture Dynamics ◽  
Rock Heterogeneity ◽  
Thermal Drilling

This paper presents a numerical study on thermal jet drilling of granite rock that is based on a thermal spallation phenomenon. For this end, a numerical method based on finite elements and a damage–viscoplasticity model are developed for solving the underlying coupled thermo-mechanical problem. An explicit time-stepping scheme is applied in solving the global problem, which in the present case is amenable to extreme mass scaling. Rock heterogeneity is accounted for as random clusters of finite elements representing rock constituent minerals. The numerical approach is validated based on experiments on thermal shock weakening effect of granite in a dynamic Brazilian disc test. The validated model is applied in three-dimensional simulations of thermal jet drilling with a short duration (0.2 s) and high intensity (approx. 3 MW m −2 ) thermal flux. The present numerical approach predicts the spalling as highly (tensile) damaged rock. Finally, it was shown that thermal drilling exploiting heating-forced cooling cycles is a viable method when drilling in hot rock mass. This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

Computational Investigation of Thrust Production of a Dolphin at Various Swimming Speeds

2021 ◽  
Author(s):  
Junshi Wang ◽  
Vadim Pavlov ◽  
Zhipeng Lou ◽  
Haibo Dong
Keyword(s):  
Surface Pressure ◽  
Swimming Performance ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Immersed Boundary ◽  
Reconstruction Method ◽  
Force Coefficient ◽  
Speed Increase ◽  
Generation Mechanisms ◽  
Thrust Production

Abstract Dolphins are known for their outstanding swimming performance. However, the difference in flow physics at different speeds remains elusive. In this work, the underlying mechanisms of dolphin swimming at three speeds, 2 m/s, 5 m/s, and 8 m/s, are explored using a combined experimental and numerical approach. Using the scanned CAD model of the Atlantic white-sided dolphin (Lagenorhynchus acutus) and virtual skeleton-based surface reconstruction method, a three-dimensional high-fidelity computational model is obtained with time-varying kinematics. A sharp-interface immersed-boundary-method (IBM) based direct numerical simulation (DNS) solver is employed to calculate the corresponding thrust production, wake structure, and surface pressure at different swimming speeds. It is found that the fluke keeps its effective angle of attack at high values for about 60% of each stroke. The total pressure force coefficient along the x-axis converges as the speed increase. The flow and surface pressure analysis both show considerable differences between lower (2 m/s) and higher (5 m/s and 8 m/s) speeds. The results from this work help to bring new insight into understanding the force generation mechanisms of the highly efficient dolphin swimming and offer potential suggestions to the future designs of unmanned underwater vehicles.

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