ACOUSTIC THREE-DIMENSIONAL EFFECTS AROUND THE TAIWAN STRAIT: COMPUTATIONAL RESULTS

1999 ◽  
Vol 07 (01) ◽  
pp. 15-26 ◽  
Author(s):  
CHI-FANG CHEN ◽  
JANG-JIA LIN ◽  
DING LEE
Keyword(s):  
Field Data ◽  
Bottom Topography ◽  
Three Dimensional ◽  
Propagation Model ◽  
Computational Results ◽  
Submarine Canyons ◽  
Offshore Area ◽  
Ocean Environment ◽  
The Taiwan Strait ◽  
Good Agreement

A set of experiments were performed in the offshore area off the coasts of Taiwan and three-dimensional (3-D) measurements recorded. The 3-D effect on underwater propagation due to azimuthal variation of bottom topography is studied for the offshore regions southwest of Taiwan, where submarine canyons exist. A 3-D acoustic propagation model, FOR3D, is used to detect the 3-D effect. Computational results show that the 3-D effect is more prominent along the axis of the canyon than across it. Calculations show a very good agreement with field data, which indicate that the 3-D effect exists in this realistic ocean environment.

The Experimental Study and Numerical Simulation of Turbulent Flow in Pumping Forebay

2009 ◽  
Author(s):  
Chao Liu ◽  
Jiren Zhou ◽  
Li Cheng
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Computational Results ◽  
Experiment Study ◽  
Study Results ◽  
Measurement Results ◽  
Good Agreement ◽  
Made In

The experiment study was made to optimize the design of a pumping forebay. The Combined-sills were made in the forebay to eliminate the circulation and vortices of the diffusing flow successfully. The Numerical simulation of three-dimensional turbulent flow is applied on the complicate fore-and-aft flow of sills. The computational results are compared with the measurement results of physical model. The calculated results are in good agreement with the experimental data. The flow pattern is obviously improved. The study results have been applied in the project which gives a uniform approach flow to the pumping sump.

On Irregular, Nonlinear Waves in a Spread Sea

1997 ◽  
Vol 119 (1) ◽  
pp. 37-41 ◽  
Author(s):  
P. Jonathan ◽  
P. H. Taylor
Keyword(s):  
Nonlinear Waves ◽  
Three Dimensional ◽  
Nonlinear Effects ◽  
Detailed Comparison ◽  
Offshore Structures ◽  
Sea Surface ◽  
Linear Wave ◽  
Ocean Environment ◽  
Wave Nonlinearity ◽  
Good Agreement

Optimal design and reassessment of offshore structures requires a good understanding of the ocean environment. The motion of the sea surface can be viewed as a three-dimensional, nonlinear stochastic process in time. In order to characterize the wave environment adequately, we need to model its random, nonlinear, and spread nature. In this paper, we address: • the expected shape of a wave near a crest or trough, • the expected shape of the ocean surface at one point, given a crest at a different point, • an efficient method to incorporate nonlinear effects within linear wave simulations, • the magnitude of wave nonlinearity as a function of wave amplitude. Detailed comparison of theory and full-scale offshore measurements at the Shell Expro Tern platform show good agreement.

scholarly journals Assessment of the Effectiveness of Combat Eyewear Protection Against Blast Overpressure

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
A. Sundaramurthy ◽  
M. Skotak ◽  
E. Alay ◽  
G. Unnikrishnan ◽  
H. Mao ◽  
...  
Keyword(s):  
Peak Pressure ◽  
Three Dimensional ◽  
Head Orientation ◽  
Computational Results ◽  
Pressure Loading ◽  
3D Finite Element ◽  
Blast Overpressure ◽  
Explosive Devices ◽  
Peak Pressures ◽  
Good Agreement

It is unclear whether combat eyewear used by U. S. Service members is protective against blast overpressures (BOPs) caused by explosive devices. Here, we investigated the mechanisms by which BOP bypasses eyewear and increases eye surface pressure. We performed experiments and developed three-dimensional (3D) finite element (FE) models of a head form (HF) equipped with an advanced combat helmet (ACH) and with no eyewear, spectacles, or goggles in a shock tube at three BOPs and five head orientations relative to the blast wave. Overall, we observed good agreement between experimental and computational results, with average discrepancies in impulse and peak-pressure values of less than 15% over 90 comparisons. In the absence of eyewear and depending on the head orientation, we identified three mechanisms that contributed to pressure loading on the eyes. Eyewear was most effective at 0 deg orientation, with pressure attenuation ranging from 50 (spectacles) to 80% (goggles) of the peak pressures observed in the no-eyewear configuration. Spectacles and goggles were considerably less effective when we rotated the HF in the counter-clockwise direction around the superior-inferior axis of the head. Surprisingly, at certain orientations, spectacles yielded higher maximum pressures (80%) and goggles yielded larger impulses (150%) than those observed without eyewear. The findings from this study will aid in the design of eyewear that provides better protection against BOP.

Application of a Navier-Stokes Solver to the Study of Open Rotor Aerodynamics

2009 ◽  
Author(s):  
Alexios Zachariadis ◽  
Cesare A. Hall
Keyword(s):  
Control Volume ◽  
Three Dimensional ◽  
Computational Approach ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Computational Results ◽  
Field Boundary ◽  
Rotor Aerodynamics ◽  
Open Rotor ◽  
Good Agreement

This paper establishes a proven computational approach for open rotor configurations that can be used as a basis for further studies involving open rotor aerodynamics and design. Many of the difficulties encountered in the application of computational fluid dynamics to an open rotor engine arise due to the removal of the casing that is present in conventional aeroengine turbomachinery. In this work, an advanced three-dimensional Navier-Stokes solver is applied to the open rotor. The approach needed to accurately capture the aerodynamics is investigated with particular attention to the mesh configuration and the specification of boundary conditions. A new three-step meshing strategy for generating the mesh and the most suitable type of far-field boundary condition are discussed. A control volume analysis approach is proposed for post-processing the numerical results for rotor performance. The capabilities of the solver and the applied methodology are demonstrated at both cruise and take-off operating conditions. The comparison of computational results with experimental measurements shows good agreement for both data trend and magnitudes.

The coastal refraction-diffraction wave propagation model

1995 ◽  
Vol 17 (4) ◽  
pp. 6-12
Author(s):  
Nguyen Tien Dat ◽  
Dinh Van Manh ◽  
Nguyen Minh Son
Keyword(s):  
Wave Propagation ◽  
Field Data ◽  
Surf Zone ◽  
Propagation Model ◽  
Wave Transformation ◽  
Diffraction Effect ◽  
Linear Wave ◽  
Diffraction Wave ◽  
Linear Wave Propagation ◽  
Wave Propagation Model

A mathematical model on linear wave propagation toward shore is chosen and corresponding software is built. The wave transformation outside and inside the surf zone is considered including the diffraction effect. The model is tested by laboratory and field data and gave reasonables results.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

scholarly journals Imaging of bi-anisotropic periodic structures from electromagnetic near-field data

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dinh-Liem Nguyen ◽  
Trung Truong
Keyword(s):  
Inverse Scattering ◽  
Maxwell Equations ◽  
Field Data ◽  
Periodic Structures ◽  
Near Field ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Inverse Scattering Problem ◽  
Factorization Method ◽  
Unique Determination

AbstractThis paper is concerned with the inverse scattering problem for the three-dimensional Maxwell equations in bi-anisotropic periodic structures. The inverse scattering problem aims to determine the shape of bi-anisotropic periodic scatterers from electromagnetic near-field data at a fixed frequency. The factorization method is studied as an analytical and numerical tool for solving the inverse problem. We provide a rigorous justification of the factorization method which results in the unique determination and a fast imaging algorithm for the periodic scatterer. Numerical examples for imaging three-dimensional periodic structures are presented to examine the efficiency of the method.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals 3D-Volume Rendering of the Pelvis with Emphasis on Paraurethral Structures Based on MRI Scans and Comparisons between 3D Slicer and OsiriX®

2021 ◽  
Vol 45 (3) ◽  
Author(s):  
C. M. Durnea ◽  
S. Siddiqi ◽  
D. Nazarian ◽  
G. Munneke ◽  
P. M. Sedgwick ◽  
...  
Keyword(s):  
Image Processing ◽  
Secondary Analysis ◽  
Three Dimensional ◽  
3D Models ◽  
Clinical Role ◽  
Cross Sectional ◽  
3D Slicer ◽  
Mri Scans ◽  
3D Volume ◽  
Good Agreement

AbstractThe feasibility of rendering three dimensional (3D) pelvic models of vaginal, urethral and paraurethral lesions from 2D MRI has been demonstrated previously. To quantitatively compare 3D models using two different image processing applications: 3D Slicer and OsiriX. Secondary analysis and processing of five MRI scan based image sets from female patients aged 29–43 years old with vaginal or paraurethral lesions. Cross sectional image sets were used to create 3D models of the pelvic structures with 3D Slicer and OsiriX image processing applications. The linear dimensions of the models created using the two different methods were compared using Bland-Altman plots. The comparisons demonstrated good agreement between measurements from the two applications. The two data sets obtained from different image processing methods demonstrated good agreement. Both 3D Slicer and OsiriX can be used interchangeably and produce almost similar results. The clinical role of this investigation modality remains to be further evaluated.

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