scholarly journals Numerical Simulation of the Hydrogen Dispersion Behavior by a Parallel Characteristic Curve Method

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qinghe Yao ◽  
Xin Pan ◽  
Qingyong Zhu
Keyword(s):  
Numerical Simulation ◽  
Open Space ◽  
Stokes Equations ◽  
Characteristic Curve ◽  
Dilution Effect ◽  
Transient Behavior ◽  
Boussinesq Approximation ◽  
Dispersion Behavior ◽  
Parallel Characteristic ◽  
Curve Method

A parallel characteristic curve method is applied in domain decomposition system to simulate the dispersion behavior of hydrogen in this work. The characteristic curve method is employed to approximate the Navier-Stokes equations and the convection diffusion equation, and the feasibility of solving complex multicomponent flow problems is demonstrated by the numerical simulation of hydrogen dispersion in a partially open space. An analogy of the Boussinesq approximation is applied and numerical results are validated by comparing them with the experimental data. The dilution effect of ventilation is investigated. The transient behavior of hydrogen and the process of accumulation in the partially open space are discussed.

Simulation of crystallization of the melt modified by nanoscale particles during laser treatment of a metal surface

2021 ◽  
Vol 1 ◽  
pp. 5-14
Author(s):  
V.N. Popov ◽  
Keyword(s):  
Numerical Simulation ◽  
Surface Layer ◽  
Stokes Equations ◽  
Solid Phase ◽  
Laser Action ◽  
Heat Removal ◽  
Boussinesq Approximation ◽  
Grain Structure ◽  
Homogeneous Distribution ◽  
Dissolved Carbon

A 2D mathematical model is proposed for the modification of an iron-based alloy with refractory nanosized particles. Numerical simulation of the processes during the modification of the surface layer of the substrate metal using the energy of a laser pulse has been carried out. Within the framework of the proposed model, the processes of heating and melting of metal on a substrate covered with a layer of nanosized refractory particles penetrating into the molten metal, convective heat transfer in the melt, and solidification after the end of the pulse are considered. Metal melting is considered in the Stefan approximation, and when the melt is cooled, the model of heterogeneous nucleation and subsequent crystallization is used. The fluid flow is described by the Navier-Stokes equations in the Boussinesq approximation. The distribution of nanoparticles in the melt is modeled by moving markers. Based on the results of calculations, the mode of pulsed laser action is determined, in which a flow is formed for a homogeneous distribution of particles of the modifying substance in the presence of a surfactant in the metal. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The liquidus temperature changes depending on the concentration of dissolved carbon in the melt. In the numerical simulation of the solidification of the surface layer of the metal, it was found that the conditions of nucleation and crystallization differ significantly in the volume of the melt. It is determined that the duration of nucleation in a supercooled melt is several tens of microseconds. The maximum number of crystallization centers occurs in areas where heat removal occurs most rapidly. With the growth of the solid phase in the melt and the release of the latent heat of crystallization, the value of supercooling decreases, the nucleation stops and the number of formed crystallization centers does not change further. The distribution of the dispersion of the crystal structure over the volume of the melted metal is estimated. It was found that as the melt cools, sequential-volume crystallization occurs.

Numerical simulation of leaking hydrogen dispersion behavior in a partially open space

2008 ◽  
Vol 33 (1) ◽  
pp. 240-247 ◽  
Author(s):  
K MATSUURA ◽  
H KANAYAMA ◽  
H TSUKIKAWA ◽  
M INOUE
Keyword(s):  
Numerical Simulation ◽  
Open Space ◽  
Dispersion Behavior

Numerical Simulation of Crystallization of a Modified Metal Drop during Metal Spreading on a Substrate

2019 ◽  
pp. 18-39
Author(s):  
V.N. Popov ◽  
A.N. Cherepanov
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Stokes Equations ◽  
Liquid Velocity ◽  
Solid Phase ◽  
Boussinesq Approximation ◽  
Solid Substrate ◽  
High Rate ◽  
Navier Stokes ◽  
Navier Stokes Equations

The purpose of the research was to numerically simulate the processes when melting drops fall on a substrate. The paper deals with the solidification on the metal surface of a binary aluminum alloy modified by activated refractory nanosized particles, which are the centers of crystalline phase nucleation. We formulated a mathematical model which describes the thermo- and hydrodynamic phenomena in the drop upon interaction with a solid substrate, heterogeneous nucleation during melt cooling, and subsequent crystallization. The flow in a liquid is described by the Navier --- Stokes equations in the Boussinesq approximation. The position of the free boundary of the melt is fixed by marker particles moving with the local liquid velocity. On the melt --- substrate contact surface, thermal resistance is taken into account. The hydrodynamic problem is considered under conditions of crystallization of molten metal. The temperature conditions and the kinetics of the growth of the solid phase in the solidifying aluminum alloy are described for various sizes of formed splats. Satisfactory agreement was found between the shape of the splat obtained by the results of numerical simulation and the available experimental data. The adequacy of the crystallization model in the presence of ultradisperse refractory particles in a binary alloy is confirmed. It was determined that, regardless of the size of the drop, bulk crystallization of the metal takes place. It was found that at a high rate of collision of a drop with a substrate during the melt spreading, a small fraction of the solid phase can be formed.

scholarly journals Derivation of water flooding characteristic curve for offshore low-amplitude structural reservoir with strong bottom water

2021 ◽  
Author(s):  
Ying-xian Liu ◽  
Jie Tan ◽  
Hui Cai ◽  
Yan-lai Li ◽  
Chun-yan Liu
Keyword(s):  
Bottom Water ◽  
Characteristic Curve ◽  
Calculated Data ◽  
Oil Production ◽  
Water Flooding ◽  
Characteristic Curves ◽  
Recoverable Reserves ◽  
Curve Method ◽  
Water Cut ◽  
Low Amplitude

AbstractThe water flooding characteristic curve method is one of the essential techniques to predict recoverable reserves. However, the recoverable reserves indicated by the existing water flooding characteristic curves of low-amplitude reservoirs with strong bottom water increase gradually, and the current local recovery degree of some areas has exceeded the predicted recovery rate. The applicability of the existing water flooding characteristic curves in low-amplitude reservoirs with strong bottom water is lacking, which affects the accurate prediction of development performance. By analyzing the derivation process of the conventional water flooding characteristic curve method, this manuscript finds out the reasons for the poor applicability of the existing water flooding characteristic curve in low-amplitude reservoir with strong bottom water and corrects the existing water flooding characteristic curve according to the actual situation of the oilfield and obtains the improvement method of water flooding characteristic curve in low-amplitude reservoir with strong bottom water. After correction, the correlation coefficient between $$\frac{{k_{ro} }}{{k_{rw} }}$$ k ro k rw and $$S_{w}$$ S w is 95.92%. According to the comparison between the actual data and the calculated data, in 2021/3, the actual water cut is 97.29%, the water cut predicted by the formula is 97.27%, the actual cumulative oil production is 31.19 × 104t, and the predicted cumulative oil production is 31.31 × 104t. The predicted value is consistent with the actual value. It provides a more reliable method for predicting low-amplitude reservoirs' recoverable ability with strong bottom water and guides the oilfield's subsequent decision-making.

scholarly journals COMPUTATIONAL FLUID DYNAMICS STUDY OF DUSTY AIR FLOW OVER NACA 63415 AIRFOIL FOR WIND TURBINE APPLICATIONS

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Iham F. Zidane ◽  
Khalid M. Saqr ◽  
Greg Swadener ◽  
Xianghong Ma ◽  
Mohamed F. Shehadeh
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
South African ◽  
Stokes Equations ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Aerodynamic Performance ◽  
Accurate Estimation ◽  
African Countries ◽  
Sand Particles

Gulf and South African countries have enormous potential for wind energy. However, the emergence of sand storms in this region postulates performance and reliability challenges on wind turbines. This study investigates the effects of debris flow on wind turbine blade performance. In this paper, two-dimensional incompressible Navier-Stokes equations and the transition SST turbulence model are used to analyze the aerodynamic performance of NACA 63415 airfoil under clean and sandy conditions. The numerical simulation of the airfoil under clean surface condition is performed at Reynolds number 460×103, and the numerical results have a good consistency with the experimental data. The Discrete Phase Model has been used to investigate the role sand particles play in the aerodynamic performance degradation. The pressure and lift coefficients of the airfoil have been computed under different sand particles flow rates. The performance of the airfoil under different angle of attacks has been studied. Results showed that the blade lift coefficient can deteriorate by 28% in conditions relevant to the Gulf and South African countries sand storms. As a result, the numerical simulation method has been verified to be economically available for accurate estimation of the sand particles effect on the wind turbine blades.

Numerical Simulation of Flowfield around High Speed Trains Passing by each other at the same Speed

2011 ◽  
Vol 97-98 ◽  
pp. 698-701
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Li Lu ◽  
Chen Guang Fan
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Point Source ◽  
High Speed ◽  
Stokes Equations ◽  
Field Structure ◽  
Vehicle Speed ◽  
Mesh Method ◽  
High Speed Trains

Large eddy simulation (LES) was made to solve the flow around two simplified CRH2 high speed trains passing by each other at the same speed base on the finite volume method and dynamic layering mesh method and three dimensional incompressible Navier-Stokes equations. Wind tunnel experimental method of resting train with relative flowing air and dynamic mesh method of moving train were compared. The results of numerical simulation show that the flow field structure around train is completely different between wind tunnel experiment and factual running. Two opposite moving couple of point source and point sink constitute the whole flow field structure during the high speed trains passing by each other. All of streamlines originate from point source (nose) and finish with the closer point sink (tail). The flow field structure around train is similar with different vehicle speed.

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