Numerical simulation of buoyant plume dispersion in a stratifice atmosphere using a lagrangian stochastic model

2003 ◽  
Vol 17 (3) ◽  
pp. 440-448
Author(s):  
Hyun Goo Kim ◽  
Yoo-Jeong Noh ◽  
Choung-Mook Lee ◽  
Don-Bum Choi
Keyword(s):  
Numerical Simulation ◽  
Stochastic Model ◽  
Plume Dispersion ◽  
Lagrangian Stochastic Model ◽  
Buoyant Plume

Turbulent dispersion in a non-homogeneous field

1999 ◽  
Vol 392 ◽  
pp. 45-71 ◽  
Author(s):  
ILIAS ILIOPOULOS ◽  
THOMAS J. HANRATTY
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Stochastic Model ◽  
Point Source ◽  
Time Scales ◽  
Langevin Equation ◽  
Turbulent Dispersion ◽  
Homogeneous Field ◽  
Fully Developed Flow ◽  
Good Agreement

Dispersion of fluid particles in non-homogeneous turbulence was studied for fully developed flow in a channel. A point source at a distance of 40 wall units from the wall is considered. Data obtained by carrying out experiments in a direct numerical simulation (DNS) are used to test a stochastic model which utilized a modified Langevin equation. All of the parameters, with the exception of the time scales, are obtained from Eulerian statistics. Good agreement is obtained by making simple assumptions about the spatial variation of the time scales.

Non-Gaussianity in turbulent relative dispersion

2019 ◽  
Vol 867 ◽  
pp. 877-905
Author(s):  
B. J. Devenish ◽  
D. J. Thomson
Keyword(s):  
Stochastic Model ◽  
Velocity Distribution ◽  
Relative Velocity ◽  
Isotropic Turbulence ◽  
Dispersion Model ◽  
Original Model ◽  
Direct Numerical Simulations ◽  
Relative Dispersion ◽  
Lagrangian Stochastic Model ◽  
Homogeneous Isotropic Turbulence

We present an extension of Thomson’s (J. Fluid Mech., vol. 210, 1990, pp. 113–153) two-particle Lagrangian stochastic model that is constructed to be consistent with the $4/5$ law of turbulence. The rate of separation in the new model is reduced relative to the original model with zero skewness in the Eulerian longitudinal relative velocity distribution and is close to recent measurements from direct numerical simulations of homogeneous isotropic turbulence. The rate of separation in the equivalent backwards dispersion model is approximately a factor of 2.9 larger than the forwards dispersion model, a result that is consistent with previous work.

scholarly journals A Stochastic Model of Stress Evolution in a Bolted Structure in the Presence of a Joint Elastic Piece: Modeling and Parameter Inference

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Mohammed Haiek ◽  
Youness El Ansari ◽  
Nabil Ben Said Amrani ◽  
Driss Sarsri
Keyword(s):  
Numerical Simulation ◽  
Maximum Likelihood ◽  
Maximum Likelihood Estimation ◽  
Stochastic Model ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Stress Evolution ◽  
Parameter Inference ◽  
Maximum Likelihood Estimation Method ◽  
Over Time

In this paper, we propose a stochastic model to describe over time the evolution of stress in a bolted mechanical structure depending on different thicknesses of a joint elastic piece. First, the studied structure and the experiment numerical simulation are presented. Next, we validate statistically our proposed stochastic model, and we use the maximum likelihood estimation method based on Euler–Maruyama scheme to estimate the parameters of this model. Thereafter, we use the estimated model to compare the stresses, the peak times, and extinction times for different thicknesses of the elastic piece. Some numerical simulations are carried out to illustrate different results.

Lagrangian Stochastic Model for the Dispersion of Solid-State Radionuclides Released from Uranium Mine Ventilation Shafts

2012 ◽  
Vol 573-574 ◽  
pp. 461-465
Author(s):  
Dong Xie ◽  
Ze Hua Liu ◽  
Jun Xiong ◽  
Yong Jun Ye
Keyword(s):  
Surface Roughness ◽  
Solid State ◽  
Stochastic Model ◽  
Atmospheric Dispersion ◽  
Three Dimensional ◽  
Mine Ventilation ◽  
Uranium Mine ◽  
Lagrangian Stochastic Model ◽  
Wind Speeds ◽  
Ventilation Shaft

Radionuclides released from uranium mine ventilation shafts would pose radiation exposure to the public and environment. A three-dimensional lagrangian stochastic model has been presented to study the atmospheric dispersion of solid-state radionuclides released from the uranium-bearing mine ventilation shafts. Meteorological conditions and geographical conditions including four downwind velocities (0.5, 1.0, 2.0, 4.0 m/s) and two underlying surface roughness characteristics (0.1 m, 1.0 m) were chose in the study. The radionuclides concentration distributions at various wind speeds and surface roughness were attained to evaluate the pollution in the vicinity of uranium mine ventilation shaft.

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