scholarly journals Numerical modelling of buried pipelines under DC stray current corrosion

2019 ◽  
Vol 9 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Yaping Zhang ◽  
Qiong Feng ◽  
Lianqing Yu ◽  
Chi-Man Lawrence Wu ◽  
Siu-Pang Ng ◽  
...  
Keyword(s):  
Environmental Problem ◽  
Three Dimensional ◽  
Corrosion Process ◽  
Comsol Multiphysics ◽  
Buried Pipelines ◽  
Stray Current ◽  
Soil Resistivity ◽  
Intensity Changes ◽  
Dimensional Equation ◽  
Corrosion Mechanisms

Corrosion of buried pipelines caused by stray currents is becoming a serious industrial and environmental problem. It is therefore necessary to study corrosion mechanisms of buried pipelines under DC stray currents in order to propose effective anti-corrosion measures. Since measurement of the potential is one of important ways to identify stray current intensity, the COMSOL Multiphysics software was used to simulate stray current corrosion dynamics of buried pipelines. It was also used to calculate the distribution and intensity changes of electrolyte potential in the cathodic protected system by solving Laplace’s three-dimensional equation. The obtained results showed that increased applied voltage leads to more positive shift of a pipeline potential, resulting in acceleration of stray current corrosion. On the contrary, increased soil resistivity can retard the corrosion process. The protected pipeline with a sacrificial anode suffers less corrosion interference than unprotected pipeline. Two crossed arrangement of pipelines makes no difference in corrosion of protected pipeline, but affects greatly on unprotected pipeline.

Study on AC Stray Current Corrosion Law of Buried Steel Pipelines

2012 ◽  
Vol 263-266 ◽  
pp. 448-451 ◽  
Author(s):  
Xin Hua Wang ◽  
Guo Yong Yang ◽  
Hai Huang ◽  
Zhenhua Chen ◽  
Li Mei Wang
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Current Density ◽  
Transmission Lines ◽  
Buried Pipelines ◽  
Safe Operation ◽  
Stray Current ◽  
Soil Resistivity ◽  
Ac Current ◽  
The Impact

AC stray current can cause AC corrosion and destroy the safe operation of buried pipelines, which comes mainly from nearby high voltage transmission lines and AC electric railway. The research and evaluation lags far behind DC stray current at home and abroad, besides, the AC current density measuring procedures are complex. Through experimental study of different parameters on the impact of the AC current density established a mathematical model of damaged area, soil resistivity, pipe-to-soil potential and coating resistivity. With it can indirectly get the AC current density, which improve efficiency by simplifying the measuring procedures. Also, provide a basis for harmfulness evaluation of AC stray current by studying the impact of AC current density on the corrosion rate.

scholarly journals Evaluation Model for the Scope of DC Interference Generated by Stray Currents in Light Rail Systems

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 746 ◽  
Author(s):  
Chengtao Wang ◽  
Wei Li ◽  
Yuqiao Wang ◽  
Shaoyi Xu ◽  
Kunpeng Li
Keyword(s):  
Surface Potential ◽  
Evaluation Model ◽  
Current Source ◽  
Electrochemical Corrosion ◽  
Potential Gradient ◽  
Light Rail ◽  
Buried Pipelines ◽  
Stray Current ◽  
Rail Systems ◽  
Transition Resistance

Electrochemical corrosion caused by stray currents reduces the lifespan of buried gas pipelines and the safety of light rail systems. Determining the scope of stray current corrosion will help prevent the corrosion of existing buried pipelines and provide an effective reference for new pipeline siting. In response to this problem, in this paper the surface potential gradient was used to evaluate the scope of stray current corrosion. First, an analytical model for the scope of the stray current corrosion combined with distributed parameters and the electric field generated by a point current source was put forward. Second, exemplary calculations were conducted based on the proposed model. Sensitivity of the potential gradient was analyzed with an example of the transition resistance, and the dynamic distribution of surface potential gradient under different locomotive operation modes was also analyzed in time-domain. Finally, the scope was evaluated at four different intervals with the parameters from the field test to judge whether the protective measures need to be taken in areas with buried pipelines and light rail systems nearby or not.

Transverse mixing of pollutants in streams: a review

2014 ◽  
Vol 41 (5) ◽  
pp. 472-482 ◽  
Author(s):  
H. Sharma ◽  
Z. Ahmad
Keyword(s):  
Vertical Mixing ◽  
Three Dimensional ◽  
Water Quality Modeling ◽  
Mixing Zone ◽  
Transverse Mixing ◽  
Know How ◽  
Advection Dispersion ◽  
Quality Modeling ◽  
Longitudinal Mixing ◽  
Dimensional Equation

Spilling or release of foreign particles in the flowing water is considered as pollution of water, and due to the inherent property of water to dissolve the substance, the particulate is well mixed in water. To monitor the extent of pollution in a stream it is essential to know how the pollutants mix in the river. It is observed that vertical mixing of pollutants is a very rapid process in the vertical directions and longitudinal mixing occurs very far from source of pollutant, which is generally out of reach of observations. Thus intermediate or transverse mixing zone is considered very important for water quality modeling. This paper is an attempt to summarize the phenomenon behind pollutant transport, reduction of three-dimensional advection–dispersion equation to two-dimensional equation, and factors causing and affecting transverse mixing of pollutants.

scholarly journals QUASICLASSICAL ANALYSIS OF THREE-DIMENSIONAL SCHRÖDINGER'S EQUATION AND ITS SOLUTION

2000 ◽  
Vol 15 (02) ◽  
pp. 83-100 ◽  
Author(s):  
M. N. SERGEENKO
Keyword(s):  
Three Dimensional ◽  
Wkb Method ◽  
Elementary Functions ◽  
Integral Of Motion ◽  
Schrödinger’S Equation ◽  
Dimensional Equation ◽  
Angular Equation ◽  
Angular Quantum Number ◽  
Schrödinger's Equation ◽  
Hamilton Jacobi Equation

Three-dimensional Schrödinger's equation is analyzed with the help of the correspondence principle between classical and quantum-mechanical quantities. Separation is performed after reduction of the original equation to the form of the classical Hamilton–Jacobi equation. Each one-dimensional equation obtained after separation is solved by the conventional WKB method. Quasiclassical solution of the angular equation results in the integral of motion [Formula: see text] and the existence of nontrivial solution for the angular quantum number l = 0. Generalization of the WKB method for multi-turning-point problems is given. Exact eigenvalues for solvable and some "insoluble" spherically symmetric potentials are obtained. Quasiclassical eigenfunctions are written in terms of elementary functions in the form of a standing wave.

On the eigenvalues in problems with spherical symmetry. Ill

1959 ◽  
Vol 252 (1271) ◽  
pp. 436-444 ◽  
Keyword(s):  
Spherical Symmetry ◽  
General Type ◽  
Three Dimensional ◽  
Lattice Points ◽  
Whole Space ◽  
Dimensional Equation

Let N (λ) denote the number of eigenvalues not exceeding λ of the three-dimensional equation ∇ 2 Ψ + {λ- q ( r )} Ψ = 0 over the whole space. The problem of the behaviour of N (λ) as λ → ∞ is considered in the case where q ( r — r c , c being a constant. It is shown that if c = 4 or 6 N (λ) = a μ 3 + b μ 2 + O (μ 5/3 ), where μ =λ 1/2+1/c and a and b are constants. This result is derived from a theorem due to van der Corput on the lattice-points in a region of a general type. It does not hold in the case c = 2, which is exceptional.

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