The BeVERLI Hill three-dimensional separating flow case: cross-facility comparisons of validation experiment results

2022 ◽  
Author(s):  
Julie E. Duetsch-Patel ◽  
Daniel MacGregor ◽  
Yngve L. Jenssen ◽  
Pierre-Yves Henry ◽  
Chittiappa Muthanna ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Separating Flow ◽  
Validation Experiment ◽  
Flow Case

scholarly journals Phase-field modeling of grain evolutions in additive manufacturing from nucleation, growth, to coarsening

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Min Yang ◽  
Lu Wang ◽  
Wentao Yan
Keyword(s):  
Additive Manufacturing ◽  
Phase Field ◽  
Field Model ◽  
Three Dimensional ◽  
Phase Field Model ◽  
Nucleation Theory ◽  
Experimental Result ◽  
Classical Nucleation Theory ◽  
Validation Experiment ◽  
Powder Particles

AbstractA three-dimensional phase-field model is developed to simulate grain evolutions during powder-bed-fusion (PBF) additive manufacturing, while the physically-informed temperature profile is implemented from a thermal-fluid flow model. The phase-field model incorporates a nucleation model based on classical nucleation theory, as well as the initial grain structures of powder particles and substrate. The grain evolutions during the three-layer three-track PBF process are comprehensively reproduced, including grain nucleation and growth in molten pools, epitaxial growth from powder particles, substrate and previous tracks, grain re-melting and re-growth in overlapping zones, and grain coarsening in heat-affected zones. A validation experiment has been carried out, showing that the simulation results are consistent with the experimental results in the molten pool and grain morphologies. Furthermore, the grain refinement by adding nanoparticles is preliminarily reproduced and compared against the experimental result in literature.

An Assessment of Three-Dimensional Turbulent Boundary Layer Prediction Methods

1973 ◽  
Vol 95 (3) ◽  
pp. 415-421 ◽  
Author(s):  
A. J. Wheeler ◽  
J. P. Johnston
Keyword(s):  
Boundary Layer ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Boundary Layer Flows ◽  
Mean Velocity ◽  
Eddy Viscosity Model ◽  
Separating Flow ◽  
Dimensional Boundary ◽  
Stress Models

Predictions have been made for a variety of experimental three-dimensional boundary layer flows with a single finite difference method which was used with three different turbulent stress models: (i) an eddy viscosity model, (ii) the “Nash” model, and (iii) the “Bradshaw” model. For many purposes, even the simplest stress model (eddy viscosity) was adequate to predict the mean velocity field. On the other hand, the profile of shear stress direction was not correctly predicted in one case by any model tested. The high sensitivity of the predicted results to free stream pressure gradient in separating flow cases is demonstrated.

scholarly journals Simultaneous Robot–World and Hand–Eye Calibration without a Calibration Object

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3949 ◽  
Author(s):  
Wei Li ◽  
Mingli Dong ◽  
Naiguang Lu ◽  
Xiaoping Lou ◽  
Peng Sun
Keyword(s):  
Three Dimensional ◽  
Real Data ◽  
Medical Robotics ◽  
Calibration Method ◽  
Bundle Adjustment ◽  
Data Sets ◽  
Rigid Transformation ◽  
Validation Experiment ◽  
Dimensional Reconstruction ◽  
Sparse Bundle Adjustment

An extended robot–world and hand–eye calibration method is proposed in this paper to evaluate the transformation relationship between the camera and robot device. This approach could be performed for mobile or medical robotics applications, where precise, expensive, or unsterile calibration objects, or enough movement space, cannot be made available at the work site. Firstly, a mathematical model is established to formulate the robot-gripper-to-camera rigid transformation and robot-base-to-world rigid transformation using the Kronecker product. Subsequently, a sparse bundle adjustment is introduced for the optimization of robot–world and hand–eye calibration, as well as reconstruction results. Finally, a validation experiment including two kinds of real data sets is designed to demonstrate the effectiveness and accuracy of the proposed approach. The translation relative error of rigid transformation is less than 8/10,000 by a Denso robot in a movement range of 1.3 m × 1.3 m × 1.2 m. The distance measurement mean error after three-dimensional reconstruction is 0.13 mm.

Three-Dimensional Simulation of Blood Flow in an Abdominal Aortic Aneurysm—Steady and Unsteady Flow Cases

1994 ◽  
Vol 116 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Tad W. Taylor ◽  
Takami Yamaguchi
Keyword(s):  
High Pressure ◽  
Blood Flow ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Unsteady Flow ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Abdominal Aortic ◽  
Flow Cycle ◽  
Flow Case

Atherosclerosis and atherosclerotic aneurysms can occur in the abdominal aorta. Steady and unsteady three-dimensional flow cases were simulated in abdominal aortic aneurysm using a flow simulation package on a graphics workstation. In the steady case, three aneurysm models of 8.0 cm length were simulated using Reynolds numbers of 350 and 700. In the unsteady case, blood flow in a single asymmetric aneurysm of 8.0 cm length was simulated at Reynolds numbers of 350 and 700 and 1400. In the aneurysm center, two symmetric vortices were formed, and flow separation started at the aneurysm inlet. In the unsteady flow case, the main vortex appeared and disappeared and changed position in the unsteady flow case and induced vortices were formed. Although the centerline view shows the vortices change position with time, cross-sectional views show that two symmetric vortices are present or partially formed throughout the entire flow cycle. Regions of high pressure were observed at the aneurysm exit caused by the symmetric vortices that were formed, implying that this high-pressure region could be an area where rupture is most likely. In the unsteady case, regions of maximum pressure moved depending on the flow cycle time; at peak flow, local pressure maximums were observed at the distal aneurysm; these oscillated, tending to put an additional strain on the distal portion of the aneurysm. The shear stress was low in the aneurysm portion of the vessel, and local maximum values were observed at the distal aneurysm constriction.

On the three-dimensional stability of a solid-body rotation flow in a finite-length rotating pipe

2016 ◽  
Vol 797 ◽  
pp. 284-321 ◽  
Author(s):  
Shixiao Wang ◽  
Zvi Rusak ◽  
Rui Gong ◽  
Feng Liu
Keyword(s):  
Finite Length ◽  
Growth Rates ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Swirl Ratio ◽  
Body Rotation ◽  
Solid Body Rotation ◽  
Instability Modes ◽  
Stability Results ◽  
Flow Case

The three-dimensional, inviscid and viscous flow instability modes that appear on a solid-body rotation flow in a finite-length straight, circular pipe are analysed. This study is a direct extension of the Wang & Rusak (Phys. Fluids, vol. 8 (4), 1996a, pp. 1007–1016) analysis of axisymmetric instabilities on inviscid swirling flows in a pipe. The linear stability equations are the same as those derived by Kelvin (Phil. Mag., vol. 10, 1880, pp. 155–168). However, we study a general mode of perturbation that satisfies the inlet, outlet and wall conditions of a flow in a finite-length pipe with a fixed in time and in space vortex generator ahead of it. This mode is different from the classical normal mode of perturbations. The eigenvalue problem for the growth rate and the shape of the perturbations for any azimuthal wavenumber $m$ consists of a linear system of partial differential equations in terms of the axial and radial coordinates ($x,r$). The stability problem is solved numerically for all azimuthal wavenumbers $m$. The computed growth rates and the related shapes of the various perturbation modes that appear in sequence as a function of the base flow swirl ratio (${\it\omega}$) and pipe length ($L$) are presented. In the inviscid flow case, the $m=1$ modes are the first to become unstable as the swirl ratio is increased and dominate the perturbation’s growth in a certain range of swirl levels. The $m=1$ instability modes compete with the axisymmetric ($m=0$) instability modes as the swirl ratio is further increased. In the viscous flow case, the viscous damping effects reduce the modes’ growth rates. The neutral stability line is presented in a Reynolds number ($Re$) versus swirl ratio (${\it\omega}$) diagram and can be used to predict the first appearance of axisymmetric or spiral instabilities as a function of $Re$ and $L$. We use the Reynolds–Orr equation to analyse the various production terms of the perturbation’s kinetic energy and establish the elimination of the flow axial homogeneity at high swirl levels as the underlying physical mechanism that leads to flow exchange of stability and to the appearance of both spiral and axisymmetric instabilities. The viscous effects in the bulk have only a passive influence on the modes’ shapes and growth rates. These effects decrease with the increase of $Re$. We show that the inviscid flow stability results are the inviscid-limit stability results of high-$Re$ rotating flows.

Design and validation of a two-dimensional variable geometry inlet

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Huacheng Yuan ◽  
Yunfei Wang ◽  
Jun Liu ◽  
Zhengxu Hua
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Back Pressure ◽  
Variable Geometry ◽  
Two Dimensional ◽  
Validation Experiment ◽  
Mach Numbers ◽  
Dimensional Variable

Abstract The design of a two-dimensional variable geometry inlet which applied to a tandem type turbine-based combined cycle (TBCC) propulsion system was investigated in the present paper through three-dimensional simulations and wind tunnel tests. The operation Mach number range was between 0 and 3. A multi-ramp geometry scheme was adopted to achieve acceptable performance at different inflow Mach number. The first ramp angle was fixed whilst the angles of the second and the third ramps were variable at different inflow Mach numbers. The Mach numbers at throat region were maintained between 1.3 and 1.5 at different inflow Mach numbers according to this variable geometry scheme. A fixed geometry rectangular-to-circular shape diffuser was adopted to improve aerodynamic performance of the inlet. Three-dimensional numerical simulations were carried out between Ma1.5 and Ma3.0. The results indicated that good aerodynamic performance can be achieved at different inflow speed. At the design point, total pressure recovery of the inlet was 0.66 at critical condition. Wind tunnel validation experiment tests were conducted at Ma2.0, showing the movement of terminal shock wave from downstream to upstream as the back pressure increased. The inlet operated at supercritical, critical and subsonic conditions at different back pressure.

scholarly journals Comparison of high-latitude line-of-sight ozone column density with derived ozone fields and the effects of horizontal inhomogeneity

2006 ◽  
Vol 6 (7) ◽  
pp. 1843-1852 ◽  
Author(s):  
W. H. Swartz ◽  
J.-H. Yee ◽  
C. E. Randall ◽  
R. E. Shetter ◽  
E. V. Browell ◽  
...  
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
Three Dimensional ◽  
Spatial Inhomogeneity ◽  
Line Of Sight ◽  
Validation Experiment ◽  
Rms Error ◽  
Horizontal Inhomogeneity ◽  
Column Ozone ◽  
Ozone Column

Abstract. Extensive ozone measurements were made during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). We compare high-latitude line-of-sight (LOS) slant column ozone measurements from the NASA DC-8 to ozone simulated by forward integration of measurement-derived ozone fields constructed both with and without the assumption of horizontal homogeneity. The average bias and rms error of the simulations assuming homogeneity are relatively small (−6 and 10%, respectively) in comparison to the LOS measurements. The comparison improves significantly (−2% bias; 8% rms error) using forward integrations of three-dimensional proxy ozone fields reconstructed from potential vorticity-O3 correlations. The comparisons provide additional verification of the proxy fields and quantify the influence of large-scale ozone inhomogeneity. The spatial inhomogeneity of the atmosphere is a source of error in the retrieval of trace gas vertical profiles and column abundance from LOS measurements, as well as a complicating factor in intercomparisons that include LOS measurements at large solar zenith angles.

scholarly journals Robust improvement solution to perspective-n-point problem

2019 ◽  
Vol 16 (6) ◽  
pp. 172988141988570
Author(s):  
Feng Youyang ◽  
Wang Qing ◽  
Yang Yuan ◽  
Yan Chao
Keyword(s):  
Three Dimensional ◽  
Image Data ◽  
Point Problem ◽  
Simulated Image ◽  
Validation Experiment ◽  
Camera Pose ◽  
Point Solution ◽  
Homogeneous Matrix ◽  
Image Pixels ◽  
Classical Computer

Perspective-n-point is a classical computer vision problem that uses three-dimensional points and image pixels to estimate camera pose. The visual robot often loses its position when the camera moves too fast or the environment changes. Perspective-n-point is used to relocate robot position, but the distribution of three-dimensional points in the world frame and different choices of coordinates affect the perspective-n-point performance and make perspective-n-point results less robust and inaccurate. In this study, we review the previous perspective-n-point algorithms and provide their disadvantages when facing three-dimensional points with large variances. According to the drawbacks of previous perspective-n-point methods, we propose a normalization method inspired by the homogeneous matrix calculation process to increase perspective-n-point algorithm accuracy and robustness. The experimental results demonstrate that the proposed perspective-n-point method is robust to different choices of coordinates and is thus better than other state-of-art perspective-n-point methods. Considering that the true camera pose is difficult to obtain, the former perspective-n-point solution validation experiment is mostly based on simulated image data. In this study, we design a new experiment based on total station and chessboard to verify the robustness and accuracy of the perspective-n-point algorithm.

Computations of the BeVERLI Hill Three-dimensional Separating Flow Model Validation Cases

2022 ◽  
Author(s):  
Aldo Gargiulo ◽  
Thomas A. Ozoroski ◽  
Thomas Hallock ◽  
Ali Haghiri ◽  
Richard D. Sandberg ◽  
...  
Keyword(s):  
Model Validation ◽  
Flow Model ◽  
Three Dimensional ◽  
Separating Flow

A Numerical Study of the Shape of the Surface Separating Flow Into Branches in Microvascular Bifurcations

1992 ◽  
Vol 114 (3) ◽  
pp. 398-405 ◽  
Author(s):  
G. Enden ◽  
A. S. Popel
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vessel Diameter ◽  
Numerical Results ◽  
Navier Stokes ◽  
Parent Vessel ◽  
Blood Constituents ◽  
Separating Flow ◽  
Wide Range

The shape of the separating surface formed by the streamlines entering the branches of microvascular bifurcations plays a major role in determining the distribution of red blood cells and other blood constituents downstream from the bifurcation. Using the finite element method, we determined the shape of the surface through numerical solution of three dimensional Navier-Stokes equations for fluid flow at low Reynolds numbers in a T-type bifurcation of circular tubes. Calculations were done for a wide range of daughter branch to parent vessel diameter ratios and flow ratios. The effect of Reynolds number was also studied. Our numerical results are in good agreement with previously reported experimental data of Rong and Carr (Microvascular Research, Vol. 39, pp. 186-202, 1990). The numerical results of this study will be used to predict the concentration of blood constituents downstream from microvascular bifurcations providing that the inlet concentration profile is known.

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