scholarly journals Three-dimensional mathematical modeling of local scour

2005 ◽  
Vol 8 ◽  
pp. 803-812 ◽  
Author(s):  
Hao ZHANG ◽  
Hajime NAKAGAWA ◽  
Taisuke ISHIGAKI ◽  
Yasunori MUTO ◽  
Yasuyuki BABA
Keyword(s):  
Mathematical Modeling ◽  
Three Dimensional ◽  
Local Scour

A Stochastic Hierarchical Population System: Excitement, Extinction and Transition to Chaos

2021 ◽  
Vol 31 (14) ◽  
Author(s):  
Irina Bashkirtseva ◽  
Tatyana Perevalova ◽  
Lev Ryashko
Keyword(s):  
Mathematical Modeling ◽  
Food Chain ◽  
Analytical Method ◽  
Three Dimensional ◽  
Biological Parameters ◽  
Top Predator ◽  
Population System ◽  
Modeling And Analysis ◽  
Transition To Chaos ◽  
Random Fluctuations

A problem of the mathematical modeling and analysis of noise-induced transformations of complex oscillatory regimes in hierarchical population systems is considered. As a key example, we use a three-dimensional food chain dynamical model of the interacting prey, predator, and top predator. We perform a comparative study of the impacts of random fluctuations on three key biological parameters of prey growth, predator mortality, and the top predator growth. A detailed investigation of the stochastic excitement, noise-induced transition from order to chaos, and various scenarios of extinction is carried out. Constructive abilities of the semi-analytical method of confidence domains in the analysis of the noise-induced extinction are demonstrated.

Study on Flow Velocity Field of Local Scour around the Pier Protected by the Sediment Storage Dam

2012 ◽  
Vol 594-597 ◽  
pp. 1975-1978
Author(s):  
Hai Jing Zhao ◽  
Dan Xun Li ◽  
Xing Kui Wang
Keyword(s):  
Velocity Field ◽  
Flow Velocity ◽  
Physical Model ◽  
Model Test ◽  
Three Dimensional ◽  
Local Scour ◽  
Physical Model Test ◽  
Three Dimensional Flow ◽  
Sediment Storage ◽  
Flow Velocity Field

Aimed at the representative project which is protected by the downstream sediment storage dam, three dimensional flow velocity field in local scour area around the separate bridge pier via physical model test was studied. The influences of shaping the eroded pit caused by the velocities in different directions were analyzed. The distribution results of flow velocity field in local scour pit near the pier protected by the sediment storage dam, deduced from the paper, will provide references for the defensive design of bridge projects.

scholarly journals Effect of Inclination Angles on the Local Scour around a Submerged Cylinder

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2687
Author(s):  
Shaohua Wang ◽  
Shiyu Yang ◽  
Zhiguo He ◽  
Li Li ◽  
Yuezhang Xia
Keyword(s):  
Inclination Angle ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Horseshoe Vortex ◽  
Local Scour ◽  
Scour Depth ◽  
Ocean Engineering ◽  
Bed Morphology

In ocean engineering and coastal environmental studies, local scour around a submerged structure is a typical issue, which is affected by the inclination of the structure. To investigate the effect of inclination directions and angles on flow structure and the bed morphology, a three-dimensional numerical model of a submerged inclined cylinder was established. In this model, the hydrodynamics are solved from the RANS (Reynolds-averaged Navier–Stokes) equations closed with the RNG k-ε turbulence model, while the bed morphology evolution is captured by the sediment transport model. In the case of vertical-cylinder scour, the simulation results agree well with existing laboratory experiments. In the cases of inclined-cylinder scour, the results show that the inclination direction not only changes the intensity and the location of the downflow but also modulates the pattern of the horseshoe vortex in front of the cylinder, thus influencing the local scour depth and the morphology of the bed. Compared with the case of vertical cylinder, the scour around an upstream-inclined cylinder is deeper, mainly due to the enhancement of downflow in front of the cylinder. The scour around a downstream-inclined cylinder is shallower and broader due to the weakened downflow and accelerated incoming flow. The maximum scour depth decreases with the inclination angle in the downstream-inclination case. In the upstream-inclination case, the maximum scour depth does not vary monotonously with the inclination angle, which results from a competitive effect of the horseshoe vortex and downflow in the front of the cylinder.

Research and Development on 3D Simulation Training Evaluation System of Substation Based on Unity3D

2015 ◽  
Vol 727-728 ◽  
pp. 987-990 ◽  
Author(s):  
Hao Zhong ◽  
Xu Chen ◽  
Wen Qian Shu ◽  
Xiao Dong Chen
Keyword(s):  
Mathematical Modeling ◽  
3D Modeling ◽  
Evaluation System ◽  
Simulation Training ◽  
Training Evaluation ◽  
Three Dimensional ◽  
Training System ◽  
Two Dimensional ◽  
Operation And Maintenance ◽  
Maintenance Personnel

In order to make training for the substation operation and maintenance personnel professional skills more effectivethis paper has designed a three-dimensional substation simulation training system based on Unity3d.In this paper,a variety of virtual scenes of the substation are studied,designed a 3Dsimulation training system of substation based on operation and maintenance personnel behavior. Framework of system comprises two-dimensional mathematical modeling, 3D modeling, development and release of platform.

scholarly journals Comparison of Three Measures to Promote National Fitness in China by Mathematical Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Pan Tang ◽  
Daqing Xu ◽  
Qing Dai ◽  
Tingting Huang
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Physical Exercise ◽  
Three Dimensional ◽  
Chinese Government ◽  
Model Parameters ◽  
National Bureau ◽  
Short Period ◽  
Key Parameter

In this paper we established a mathematical model for national fitness in China. Based on a questionnaire and data of the General Administration of Sport of China and the National Bureau of Statistics of China, the dynamics for three classes of people are expressed by a system of three-dimensional ordinary equations. Model parameters are estimated from the data. This study indicated that national fitness put out by the Chinese government is reasonable. By finding the key parameter, the best measure to promote national fitness is put forward. In order to increase the number of people who frequently participate in sport exercise in a short period of time, if only one measure can be chosen, guiding people who never take part in physical exercise will be the best measure.

On the Mathematical Modeling of Heat Transfer Characteristics of Turbulent Flames in Industrial Furnaces

2002 ◽  
Author(s):  
Essam E. Khalil
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Flow Pattern ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Wall Heat Transfer ◽  
Governing Equations ◽  
Heat Transfer Characteristics ◽  
Combustion Chambers ◽  
Transfer Characteristics

The recent advances in numerical methods and the vast development of computers had directed the designers to better development and modifications to air flow pattern and heat transfer in combustion chambers. Extensive efforts are exerted to adequately predict the air velocity and turbulence intensity distributions in the combustor zones and to reduce the emitted pollution and noise abatement to ultimately produce quite and energy efficient combustor systems. The present work fosters mathematical modeling techniques to primarily predict what happens in three-dimensional combustion chambers simulating boiler furnaces, areo engines in terms of flow regimes and interactions. The present work also demonstrates the effect of chamber design and operational parameters on performance, wall heat transfer under various operating parameters. The governing equations of mass, momentum and energy are commonly expressed in a preset form with source terms to represent pressure gradients, turbulence and viscous action. The physical and chemical characteristics of the air and fuel are obtained from tabulated data in the literature. The flow regimes and heat transfer play an important role in the efficiency and utilization of energy. The results are obtained in this work with the aid of the three-dimensional program 3DCOMB; applied to axisymmetrical and three-dimensional complex geometry with and without swirl with liquid or gaseous fuels. The present numerical grid arrangements cover the combustion chamber in the X, R or Y and Z coordinates directions. The numerical residual in the governing equations is typically less than 0.001%. The obtained results include velocity vectors, turbulence intensities and wall heat transfer distributions in combusors. Examples of large industrial furnaces are shown and are in good agreement with available measurements in the open literature. One may conclude that flow patterns, turbulence and heat transfer in combustors are strongly affected by the inlet swirl, inlet momentum ratios, combustor geometry. Both micro and macro mixing levels are influential. The present modeling capabilities can adequately predict the local flow pattern and heat transfer characteristics in Complex combustors. Proper representation of the heat transfer and radiation flux is important in adequate predictions of large furnace performance.

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