scholarly journals Single Droplet on Micro Square-Post Patterned Surfaces – Theoretical Model and Numerical Simulation

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Y. Q. Zu ◽  
Y. Y. Yan
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Patterned Surfaces ◽  
Single Droplet

Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Songjing Li ◽  
Jixiao Liu ◽  
Dan Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Experimental Studies ◽  
Gas Bubbles ◽  
Chamber Pressure ◽  
Dynamic Characterization ◽  
Valveless Micropump ◽  
Performance Deterioration ◽  
Trapped Gas

Unexpected gas bubbles in microfluidic devices always bring the problems of clogging, performance deterioration, and even device functional failure. For this reason, the aim of this paper is to study the characterization variation of a valveless micropump under different existence conditions of gas bubbles based on a theoretical modeling, numerical simulation, and experiment. In the theoretical model, we couple the vibration of piezoelectric diaphragm, the pressure drop of the nozzle/diffuser and the compressibility of working liquid when gas bubbles are entrapped. To validate the theoretical model, numerical simulation and experimental studies are carried out to investigate the variation of the pump chamber pressure influenced by the gas bubbles. Based on the numerical simulation and the experimental data, the outlet flow rates of the micropump with different size of trapped gas bubbles are calculated and compared, which suggests the influence of the gas bubbles on the dynamic characterization of the valveless micropump.

Investigation on penetration model of shaped charge jet in water

2016 ◽  
Vol 30 (02) ◽  
pp. 1550268 ◽  
Author(s):  
Jinwei Shi ◽  
Xingbai Luo ◽  
Jinming Li ◽  
Jianwei Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Model Simulation ◽  
Theoretical Models ◽  
Theoretical Research ◽  
Water Medium ◽  
Simulation Results ◽  
Jet Penetration ◽  
The Impact ◽  
Penetration Velocity

To analyze the process of jet penetration in water medium quantitatively, the properties of jet penetration spaced target with water interlayer were studied through test and numerical simulation. Two theoretical models of jet penetration in water were proposed. The theoretical model 1 was established considering the impact of the shock wave, combined with the shock equation Rankine–Hugoniot and the virtual origin calculation method. The theoretical model 2 was obtained by fitting theoretical analysis and numerical simulation results. The effectiveness and universality of the two theoretical models were compared through the numerical simulation results. Both the models can reflect the relationship between the penetration velocity and the penetration distance in water well, and both the deviation and stability of theoretical model 1 are better than 2, the lower penetration velocity, and the larger deviation of the theoretical model 2. Therefore, the theoretical model 1 can reflect the properties of jet penetration in water effectively, and provide the reference of model simulation and theoretical research.

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

High-speed train–track–bridge dynamic interactions – Part I: theoretical model and numerical simulation

2013 ◽  
Vol 1 (1-2) ◽  
pp. 3-24 ◽  
Author(s):  
Wanming Zhai ◽  
He Xia ◽  
Chengbiao Cai ◽  
Mangmang Gao ◽  
Xiaozhen Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
High Speed ◽  
High Speed Train ◽  
Train Track ◽  
Dynamic Interactions ◽  
Track Bridge

Numerical Simulation of a Particle in Air Flow Around a Turbine Blade

2020 ◽  
Author(s):  
Ippei Oshima ◽  
Mikito Furuichi
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Turbine Blade ◽  
Gas Flow ◽  
Three Dimensional ◽  
Prediction Method ◽  
Stokes Number ◽  
Lagrangian Simulation ◽  
Background Gas ◽  
Liquid Mass Flow Rate

Abstract The Steam turbine is widely used for generating electricity, in the thermal, nuclear and geothermal power generation systems. A wet loss is known as one of the degrading factors of the performance. To reduce the amount of liquid phase generated by condensation and atomization from nozzles, the prediction of the distribution of liquid mass flow rate inside the turbine is important. However, the quantitative understanding and the prediction method of the liquid flow inside the turbine remain unclear because physics inside a turbine is consisting of complex multiscale and multiphase events. In the present study, we proposed a theoretical model predicting the motion of droplet particles in gas flow based on Stokes number whose model does not require numerical simulation. We also conducted the numerical validation test using three-dimensional Eulerian-Lagrangian simulation for the problem with turbine blade T106. The numerical simulation shows that the particle motion is characterized by the Stokes number, that is consistent with the assumption of the theoretical model and previous studies. When Stokes number is smaller than one, the particle trajectory just follows the gas flow streamline and avoids the impacts on the surface of T106. With increasing Stokes number, the particles begin to deviate from the gas flow. As a result, many particles collide with the surface of T106 when the Stokes number is approximately one. When the Stokes number is extremely larger than one, particles move straight regardless of the background gas flow. The good agreements between the theoretical predictions and numerical experiment results justify the use of our proposed theoretical model for the prediction of the particle flow around the turbine blade.

The Numerical Simulation of Effective Elastic Response for WC-Co Cemented Carbide

2015 ◽  
Vol 1096 ◽  
pp. 417-421
Author(s):  
Pei Luan Li ◽  
Zi Qian Huang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Model ◽  
Material Properties ◽  
Cemented Carbide ◽  
Elastic Response ◽  
The Finite Element Method ◽  
Simulation Results ◽  
Element Method

By the use of finite element method, this paper predicts the effects of the shapes of reinforcements with different ductility (Co) on the effective elastic response for WC-Co cemented carbide. This paper conducts a comparative study on the material properties obtained through theoretical model, numerical simulation and experimental observations. Simulation results indicate that the finite element method is more sophisticated than the theoretical prediction.

scholarly journals Numerical Simulation of 980 nm-LD-Pumped Yb3+-Er3+-Tm3+-Codoped Fiber Amplifier for 1500 nm and 1600 nm Bands

2009 ◽  
Vol 2009 ◽  
pp. 1-8
Author(s):  
Chun Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Pump Power ◽  
Fiber Length ◽  
Fiber Amplifier ◽  
Numerical Results ◽  
Experimental Result ◽  
Signal Wavelength ◽  
Gain Spectra ◽  
Good Agreement

The theoretical model of Yb3+-Er3+-Tm3+-codoped fiber amplifier pumped by 980 nm laser is proposed, and the rate and power propagation equations are numerically solved to analyze the dependences of the gains at 1500 nm and 1600 nm bands on the activator concentrations, fiber length, pump power, and signal wavelength. The numerical results show that our model is in good agreement with experimental result, and with pump power of 200 mW and fiber length varying from 0.15 to 1.5 m, the gains at the two bands may reach 10.0–20.0 dB when the codoping concentrations of Yb3+, Er3+, and Tm3+ are in the ranges 1.0–3.0×1025, 1.0–3.0×1024, and 1.0–3.0×1024 ions/m3, respectively. The fiber parameters may be optimized to flatten the gain spectra.

Analysis on the Cycle Characteristics of Dual Swash Plate Stirling Engine

2013 ◽  
Vol 724-725 ◽  
pp. 946-950 ◽  
Author(s):  
Xu Dong Han ◽  
Wei Zheng Xu
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Mechanical Energy ◽  
Stirling Engine ◽  
Design Parameters ◽  
Swash Plate ◽  
Fundamental Information ◽  
Waste Energy

Dual swash plate Stirling engine was designed to convert the waste energy of the flame to mechanical energy. A Stirling model has been developed and used to optimize the performance and design parameters of the engine. The Schmidt analysis is used to obtain the internal engine pressure for the adiabatic analysis. The objective of this paper is to provide fundamental information and present a detailed feasibility of dual the swash plate mechanism. Based on the theoretical model and numerical simulation, the Stirling power is calculated. The result shows that the swash plate mechanism could be applied in practice.

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