Computational Reconstruction of Fluctuating Flow Field in the Ocean

2002 ◽  
Author(s):  
Kei Sato ◽  
Toru Sato
Keyword(s):  
Flow Field ◽  
Spatial Scale ◽  
Field Measurement ◽  
Measurement Data ◽  
Measured Data ◽  
Computational Domain ◽  
Computational Reconstruction

Two methods for computational reconstruction of fluctuating flows in the ocean based on field measurement data are suggested. Here full-3D treatment with the spatial scale of O(100m)–O(1000m) is taken into account. In the first method, the fluctuating flow based on measurement data is generated at inflow boundary and introduced into computational domain. In the second method, small wavenumber components of fluctuation in the ocean are forced in computational domain, and large wavenumber components are generated automatically. The results of each method are discussed with comparing with measured data, and effectiveness of each method is shown.

scholarly journals A Fatigue Reliability Assessment for Rail Tension Clamps Based on Field Measurement Data

2022 ◽  
Vol 12 (2) ◽  
pp. 624
Author(s):  
Ji-Hyeon Kim ◽  
Yeun-Chul Park ◽  
Mancheol Kim ◽  
Hyoung-Bo Sim
Keyword(s):  
Field Measurement ◽  
Reliability Index ◽  
Reliability Assessment ◽  
Measurement Data ◽  
Measured Data ◽  
Field Observations ◽  
Fatigue Reliability ◽  
Statistical Parameters ◽  
Train Operation ◽  
Number Of Cycles

Tension clamps play an important role in maintaining the track gauge by fixing the rails to the sleepers. Damage to the tension clamps was observed on an urban railway. The cause of the fracturing of the tension clamps was identified and reliability analyses on the fatigue failure of the tension clamps were performed. The stress ranges were estimated by measuring the strain at the locations where most of the fractures occurred during train operation. Afterward, a statistical model of the stress ranges was developed using the measured data. The statistical parameters of the stress ranges for the reliability analysis were estimated based on the field measurement data. The reliability indexes were calculated for the inner and outer rails and for the inside and outside track gauges of each rail. The variations of the reliability index for the years in service and the number of cycles were investigated. The results of the reliability analyses showed a consistency with the field observations.

Separation Method of Strain Caused by Concrete Shrinkage and Creep in Bridge Health Monitoring

2014 ◽  
Vol 668-669 ◽  
pp. 1421-1425
Author(s):  
Ya Feng Gong ◽  
Xiao Bo Sun ◽  
Xiang Hui Li ◽  
Yu Bo Jiao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Health Monitoring ◽  
Field Measurement ◽  
Measurement Data ◽  
Element Model ◽  
Measured Data ◽  
Bridge Health Monitoring ◽  
Concrete Shrinkage ◽  
Shrinkage And Creep

The strain caused by concrete shrinkage and creep is separated through the field measurement data in this paper. Then D62 model and ACI model of finite element model is established to predict shrinkage and creep. Compared with the measured data, the feasibility and practicability of these two models can be proved.

Multi-peaked directional wave spectra based on extensive field measurement data in the Gulf of Oman

2021 ◽  
Vol 230 ◽  
pp. 109057
Author(s):  
Mohammad Adibzade ◽  
Mehdi Shafieefar ◽  
Hassan Akbari ◽  
Roozbeh Panahi
Keyword(s):  
Field Measurement ◽  
Measurement Data ◽  
Wave Spectra ◽  
Gulf Of Oman ◽  
Extensive Field ◽  
Directional Wave

scholarly journals Analysis of transonic buffet using dynamic mode decomposition

2021 ◽  
Vol 62 (4) ◽  
Author(s):  
Antje Feldhusen-Hoffmann ◽  
Christian Lagemann ◽  
Simon Loosen ◽  
Pascal Meysonnat ◽  
Michael Klaas ◽  
...  
Keyword(s):  
Shock Wave ◽  
Flow Field ◽  
Acoustic Waves ◽  
Feedback Loop ◽  
Measurement Data ◽  
Dynamic Mode Decomposition ◽  
Recirculation Region ◽  
Dynamic Mode ◽  
Mode Decomposition ◽  
Transonic Buffet

AbstractThe buffet flow field around supercritical airfoils is dominated by self-sustained shock wave oscillations on the suction side of the wing. Theories assume that this unsteadiness is driven by a feedback loop of disturbances in the flow field downstream of the shock wave whose upstream propagating part is generated by acoustic waves. High-speed particle-image velocimetry measurements are performed to investigate this feedback loop in transonic buffet flow over a supercritical DRA 2303 airfoil. The freestream Mach number is $$M_{\infty } = 0.73$$ M ∞ = 0.73 , the angle of attack is $$\alpha = 3.5^{\circ }$$ α = 3 . 5 ∘ , and the chord-based Reynolds number is $${\mathrm{Re}}_{c} = 1.9\times 10^6$$ Re c = 1.9 × 10 6 . The obtained velocity fields are processed by sparsity-promoting dynamic mode decomposition to identify the dominant dynamic features contributing strongest to the buffet flow field. Two pronounced dynamic modes are found which confirm the presence of two main features of the proposed feedback loop. One mode is related to the shock wave oscillation frequency and its shape includes the movement of the shock wave and the coupled pulsation of the recirculation region downstream of the shock wave. The other pronounced mode represents the disturbances which form the downstream propagating part of the proposed feedback loop. The frequency of this mode corresponds to the frequency of the acoustic waves which are generated by these downstream traveling disturbances and which form the upstream propagating part of the proposed feedback loop. In this study, the post-processing, i.e., the DMD, is highlighted to substantiate the existence of this vortex mode. It is this vortex mode that via the Lamb vector excites the shock oscillations. The measurement data based DMD results confirm numerical findings, i.e., the dominant buffet and vortex modes are in good agreement with the feedback loop suggested by Lee. Graphic abstract

scholarly journals Design of a Double-Nozzle Air Spray Gun and Numerical Research in the Interference Spray Flow Field

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 475
Author(s):  
Yin-An Wang ◽  
Xiao-Peng Xie ◽  
Xiao-Hui Lu
Keyword(s):  
Flow Field ◽  
Central Region ◽  
Interference Effect ◽  
Thickness Distribution ◽  
Computational Domain ◽  
Coating Film ◽  
Discrete Phase Model ◽  
Spray Painting ◽  
Flow Field Characteristics ◽  
Spray Gun

Spray painting robots equipped with air spray guns have been widely used in the painting industry. In view of the low efficiency of single-nozzle air spray guns when spraying large targets, a new double-nozzle air spray gun structure was designed in this paper based on the Coanda effect of double jets. Firstly, a 3-D physical model of the double-nozzle air spray gun was built in Solidworks, in which unstructured grids were generated for the computational domain by ICEM. Secondly, the spray painting process was numerically modeled with the help of the computational fluid dynamics (CFD) software ANSYS-Fluent 16.0. The two-phase spray flow was calculated by coupling a discrete phase model (DPM) and the Taylor analogy breakup (TAB) method. The TAB model was applied to predict the secondary break-up. The DPM model was applied to predict the droplet trajectories. The geometry of an air spray gun has a significant influence on the spray flow field characteristics. The influence of the air spray gun geometry on the interference spray flow field characteristics and coating film thickness distribution were investigated by changing the values of the distance between the centers of the two paint holes (L) and the angle between the axes of the two paint holes (θ). Numerical results show that the smaller L and θ are, the stronger the interference effect between the two jets, while the more concentrated the paint is in the central region of the target surface, the easier it is for overspray to occur. With increasing L and θ, the interference effect gradually decreased and the extension distance of the coating film along the x-axis gradually increased. However, if L and θ are too large, the interference effect will become too weak and the shape of the coating film will become a concave, with more paint on both side regions and less paint in the central region, which will cause an uneven coating film. From the simulation results, it can be concluded that a more uniform coating film can be obtained when L = 30 mm and θ = 10°. The effective coating width of the double-nozzle air spray gun was increased by 85.7% compared with the single-nozzle air spray gun, which improved the spraying efficiency.

Detection and Analysis of Rats’ Bioelectromagnetic Signal

2014 ◽  
Vol 536-537 ◽  
pp. 13-17
Author(s):  
Hong Long Cao ◽  
Fen Ju Qin ◽  
Xue Guan Liu ◽  
He Ming Zhao
Keyword(s):  
Standard Deviation ◽  
Automatic System ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Biological Activities ◽  
Measurement Data ◽  
Measured Data ◽  
The Mean ◽  
Frequency Window ◽  
Window Effects

In this paper, we designed an automatic system and automatic test software, and they can carry out Kunming rats bioelectromagnetic measurement in standard status and anesthesia automatically in anechoic chamber where the electromagnetic field outside is shielded, the reflection wave is absorbed, and the measurement accuracy will be improved. We get a great number of measurement data with frequency-sweep measurement method. The mean and standard deviation of amplitudes vs. frequencies is calculated and analyzed. The results show the measurement method is feasible. We have plotted the means of measured data as multiple sets of Y values in a series of bars with standard deviations bars included and distributed in the frequency axis of X. It is found that the fluctuation of the mean and standard deviation in some frequencies is not evident which may explain frequency window effects, while in other frequencies, such a fluctuation can be obviously observed, which may suggest that bioelectromagnetic signal is influenced by biological activities (standard and anaesthesia status) in these frequency points.

In Situ Stress Measurement and Inversion in Deep Roadway

2013 ◽  
Vol 734-737 ◽  
pp. 759-763 ◽  
Author(s):  
Yong Li ◽  
Yun Yi Zhang ◽  
Ren Jie Gao ◽  
Shuai Tao Xie
Keyword(s):  
Field Measurement ◽  
Stress Measurement ◽  
Measurement Data ◽  
Back Analysis ◽  
In Situ Stress ◽  
Deep Mine ◽  
Accuracy Requirement ◽  
Initial Stress Field ◽  
In Situ Stress Measurement

Jixi mine area is one of the early mined areas in China and it's a typical deep mine. Because of large deformation of underground roadway and dynamic disasters occurred frequently in this mine, five measurement points of in-situ stress in this mine was measured and then analyzed with inversion. Based on these in-situ stress measurement data, numerical model of 3D in-situ stress back analysis was established. According to different stress fields, related analytical samples of neural network were given with FLAC program. Through the determination of hidden layers, hidden nodes and the setting of parameters, the network was optimized and trained. Then according to field measurement of in-situ stress, back analysis of initial stress field was conducted. Compared with field measurement, with accuracy requirement satisfied, it shows that the in-situ stress of rock mass obtained is basically reasonable. Meanwhile, it proves that the measurement of in-situ stress can provide deep mines with effective and rapid means, and also provide reliable data to optimization of deep roadway layout and supporting design.

Research on the Pollution Diffusion Regularity near Sewage Outlet Areas in Yuncheng Reach of the Fen River

2011 ◽  
Vol 383-390 ◽  
pp. 2430-2436
Author(s):  
Jian Hua Hou ◽  
Min Quan Feng ◽  
Xiao Peng Xing ◽  
Zhen Hua Hou
Keyword(s):  
Water Quality ◽  
Flow Field ◽  
Water Depth ◽  
Concentration Gradient ◽  
River Flow ◽  
Measured Data ◽  
Quality Model

The purpose of this paper is to find the pollution diffusion regularity near sewage outlet area of Yuncheng reach of the Fen River. A 2-D water hydrodynamic and quality model was used to simulate flow field, the water quality and contamination dispersion. The parameters of the model were calibrated with measured data of the water depth, flow and water quality in Yuncheng reach of the Fen River. According to the simulated result, the total area of pollution belt with 19 sewage outlets is 8.89km2 in normal year. And 3.89% of the reach has a worse water quality than V class in standard. The percentage of V and Ⅳ Class of water is 69.17% and 26.94%.In dry year, the total area of pollution belt with 19 sewage outlets is 8.89km2.The percentage of inferior V, V and Ⅳ Class of water is 27.80%, 69.46% and 2.74%. It was shown by the simulated results that the concentration gradient decreases with increasing distance to the outlets and the dilution and dispersion of pollutants was enhanced by a greater river flow.

Numerical Investigation of a Fiber Web Effect on the Pressure Drop and Particles Collection in a Microchannel

2009 ◽  
Author(s):  
Alireza Dastan ◽  
Omid Abouali
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Numerical Investigation ◽  
Particle Motion ◽  
Particle Deposition ◽  
Hydraulic Diameter ◽  
Lagrangian Approach ◽  
Computational Domain ◽  
Governing Equations ◽  
Eulerian Approach

In this paper pressure drop and particle deposition in a microchannel with a hydraulic diameter of 225 micrometer is investigated numerically. Several hundred micron length fibers caught at the entrance of the channels making a “fiber web” also is modeled in this research. Governing equations for the flow field are solved with an Eulerian approach while the equations of particle motion in the flow are solved by a Lagrangian approach. Assuming the symmetry in the domain, one channel and the corresponding plenum are studied in the computational domain. For studying the effects of fibers in the flow, two fiber webs with four and six solid fibers are studied. The increase of pressure drop in the microchannel because of the entrance fiber web is computed and discussed. Also deposition and collection of the particles with various diameters at the fiber webs are also presented.

Experimental investigation of the air flow in a simplified underhood environment

2021 ◽  
pp. 095440702110597
Author(s):  
Randi Franzke ◽  
Simone Sebben ◽  
Emil Willeson
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Air Flow ◽  
Measurement Data ◽  
Quality Measurement ◽  
Flow Distribution ◽  
Lateral Position ◽  
Reference Case ◽  
Lateral Direction

In this paper, a simplified underhood environment is proposed to investigate the air flow distribution in a vehicle-like set-up and provide high quality measurement data that can be used for the validation of Computational Fluid Dynamic methods. The rig can be equipped with two types of front openings representative for electrified vehicles. Furthermore, it is possible to install differently shaped blockages downstream of the fan to imitate large underhood components. The distance between the blockages and the fan can be varied in longitudinal and lateral direction. The measurements are performed with Laser Doppler Anemometry at a fixed distance downstream of the fan. The results show that the lack of an upper grille opening in the configuration for a battery electric vehicle has a notable impact on the flow field in the reference case without any downstream blockage. However, the differences in the flow field between the two front designs become less when a downstream obstruction is present. The longitudinal and lateral position of the blockages have a minor impact on the flow field compared to the shape of the obstacle itself.

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