|
Modeling and simulation of droplet translocation and fission by electrowetting-on-dielectrics (EWOD)
Nathan HOWELL, Weihua LI
Front Mech Eng Chin. 2010, 5 (4): 376-388.
https://doi.org/10.1007/s11465-010-0104-z
This paper discusses methods of microfluidic droplet actuation by means of electrowetting-on-dielectrics (EWOD) and provides a technique for modeling and simulating a microfluidic device by using the computational fluid dynamics (CFD) program, Flow3D. Digital or droplet microfluidics implies the manipulation of droplets on a scale of nanoliters (10-9 L) to femtoliters (10-15 L), as opposed to continuous microfluidics that involve the control of continuous fluid within a channel. The two operations in focus here are droplet translocation (moving) and droplet fission (splitting), in which the pressures and velocities within the droplet are analyzed and compared to existing works, both theoretical and experimental. The variation in the pressure of the leading and trailing faces of a droplet indicates the variation in surface energy—an important parameter that explains how a droplet will move toward a region of higher electric potential. The higher voltage on one side of a droplet reduces surface energy, which leads to an induced pressure drop, thus resulting in fluid motion. Flow3D simulations are for both water and blood droplets at voltages between 50 V and 200 V, and the droplet size, surface properties (Teflon coated), and geometry of the system are kept constant for each operation. Some peculiarities of the simulation are brought to light, such as instabilities of the system to higher voltages and fluids with higher dielectric constants, as well as the creation of a tertiary droplet when the applied voltage causes a large enough force during fission. The force distribution across the droplet provides a general understanding of the electrowetting effect and more specifically allows for a comparison between the effects that different voltages have on the forces at the droplet surface. The droplet position and mean kinetic energy of the droplet are also investigated and compared to other works, proving the dynamics of a droplet motion found here.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Explicit optimization method for cutting-screw-thread on the basis of dual-RSM
Zhengbao LEI, Shubin WEI, Qingyun DU
Front Mech Eng Chin. 2010, 5 (4): 423-430.
https://doi.org/10.1007/s11465-010-0109-7
To obtain the explicit function for optimizing the cutting-screw-thread (CST) in crash, the simulations of frontal crash at the speed of 56 km/h have been carried out in VPG. The peak acceleration in crash has been taken as the evaluation index of energy absorption characteristics. First, the single factor experiment was taken based on six parameters affecting on the absorption characteristics of CST. Second, the peak acceleration function of each parameter by using response surface method (RSM) is obtained. Third, the explicit resultant peak acceleration function of six parameters by using RSM again is obtained. A dual RSM-based explicit method is proposed. According to this function, the best size dimensions of CST in different crash conditions could be easily obtained. Finally, an example shows that the values of the calculation errors for simulation value and target value (40 g) are 3.6% and 1.3%, respectively. This method can satisfy the demand for engineering accuracy.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Rotating magnetic beacons magnetic field strength size in SAGD
Bing TU, Desheng LI, Enhuai LIN, Bin LUO, Jian HE, Lezhi YE, Jiliang LIU, Yuezhong WANG
Front Mech Eng Chin. 2010, 5 (4): 446-449.
https://doi.org/10.1007/s11465-010-0113-y
Rotation magnetic beacons magnetic field strength is very important to drill parallel horizontal twin wells in steam assisted gravity drainage (SAGD). This paper analyzes a small magnet with a diameter of 25.4 mm. At each end, there is a length of 12.6 mm with permanent magnet, and in the middle, there is a length of 78 mm with magnetic materials. The magnetic field strength generated by the magnetic material of 1J12, 1J50, and 1J79 is analyzed, respectively. ANSOFT software is used to simulate the magnetic field strength generated by different magnetic materials above, which also be tested through experimental methods. The comparison of the simulation and experimental results show that experimental and simulation results are basically consistent, and the results can meet the specific requirements of engineering applications.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Technology and system of constraint programming for industry production scheduling — Part I: A brief survey and potential directions
Yarong CHEN, Zailin GUAN, Yunfang PENG, Xinyu SHAO, Muhammad HASSEB
Front Mech Eng Chin. 2010, 5 (4): 455-464.
https://doi.org/10.1007/s11465-010-0106-x
The use of techniques and system of constraint programming enables the implementation of precise, flexible, efficient, and extensible scheduling systems. It has been identified as a strategic direction and dominant form for the application into planning and scheduling of industrial production. This paper systematically introduces the constraint modeling and solving technology for production scheduling problems, including various real-world industrial applications based on the Chip system of Cosytec Company. We trend of some concrete technology, such as modeling, search, constraint propagation, consistency, and optimization of constraint programming for scheduling problems. As a result of the application analysis, a generic application framework for real-life scheduling based on commercial constraint propagation (CP) systems is proposed.
Figures and Tables |
References |
Related Articles |
Metrics
|
18 articles
|