Simulation solution for micro droplet impingement on a flat dry surface

This paper presents a computational fluid dynamics approach for micro droplet impacting on a flat dry surface. A two-phase flow approach is employed using FLUENT VOF multiphase model to calculate the flow distributions upon impact. The contact line velocity is tracked to calculate the dynamic contact angle through user defined function program. The study showed that the treatment of contact line velocity is crucial for the accurate prediction of droplet impacting on poor wettability surfaces. On the other hand, it has much less influence on the simulation of droplet impacting on good wettability surfaces. Good fit between simulation results and experimental data is obtained using this model.

TYPHOON POSITIONING METHOD USING DUAL-RADAR ZERO RADIAL VELOCITY LINES AND PRELIMINARY TEST

Timely and relatively accurate detection of the center position of a near-landfalling typhoon is essential for weather forecasts, warning, disaster preparedness and data assimilation. Due to the vortex like nature of the flow near the typhoon center, the Zero Radial Velocity Line(ZRVL) of a Doppler radar extends through the typhoon center and the radar site. This paper proposes a method to detect the typhoon center by intersecting the ZRVLs of a dual-Doppler radar system. Simulation with Rankine Vortex model shows the validity of this method. This paper also evaluated the method by locating the centers of Typhoon FUNG-WONG(No. 201416) which impacted the east coastal regions of China from the afternoon of 22 September to the morning of 23 September, 2014 BST(Beijing Standard Time). During this period, the centers of the coastal typhoon were precisely positioned by intersecting the ZRVLs of two Doppler radars. The positioning accuracy of this method is comparable to that from Automatic Weather Stations(AWS) wind data. This method is suitable for areas where AWS data are unavailable, supposing radars are apart 100 km with a maximum unambiguous distance of 148 km, this technique can cover most regions effectively.

Control of vacuum arc source cathode spots contraction motion by changing electromagnetic field

This paper investigates the magnetic field component impact on cathode spots motion trajectory and the mechanism of periodic contraction.Electromagnetic coils and permanent magnets were installed at the different sides of cathode surface,the photographs of cathode spots motion trajectory were captured by a camera.Increasing the number of magnets and decreasing the distance between magnets and cathode both lead to enhancing cathode spots motion velocity.Radii of cathode spots trajectory decrease gradually with the increasing of electromagnetic coil＇s current,from 40 mm at 0 A to 10 mm at 2.7 A.Parallel magnetic field component intensity influence the speed of cathode spots rotate motion,and perpendicular magnetic field component drives spots drift in the radial direction.Cathode spot＇s radial drift is controlled by changing the location of the ‘zero line＇ where perpendicular magnetic component shifts direction and the radius of cathode spots trajectory almost equal to ‘zero line＇.

Individual-based simulation of the diffusion process of Eupatorium adenophorum

In order to investigate the diffusion patterns of Eupatorium adenophorum, this study uses a computer to simulate various plant diffusion processes under different environments. The study develops binary cellular automata as a framework reflecting the growth and semination of plants by the change of cellular state and transition function. This model allocates 16 integers, namely 1 to 16, to indicate a life history of plant starting from seed. In each iteration （a year）, Monte-Carlo simulation is applied to decide whether an individual survives into the next year, the probability of which is estimated from previous literature. If a plant survives youth, mature or senile period, its propagation will also be considered and short-tailed dispersal kernel was employed. Applying this basic model, this study also simulates the diffusion process of E. adenophorum under four typical ecological environments. Examining the age structure of the four populations, we found that, although with significantly different numbers of plants left, most individuals were in the infancy period. Besides, their dispersal velocity showed different periodic law. These observations provided reasonable suggestions on what control strategies to be taken respectively.

To improve alignment of isoindigo-based conjugated polymer film by controlling contact line receding velocity

The macroscopic alignment of conjugated polymers with low grain boundary is essential to carrier transport. During film forming process, the match between contact line receding velocity and the critical alignment velocity is essential to get the alignment polymer film. In this paper, the contact line receding velocity of a D-A conjugated polymer film, isoindigo and bithiophene（IIDDT-C3）, was adjusted by solvent vapor content and film-formation temperature. Only when solvent vapor content was 0.3 m L and the film-formation temperature was 90C, the contact line receding velocity was in accordance with the critical alignment velocity, and the highest degree of alignment was attained in the IIDDT-C3 film, with the dichroic ratio up to 4.08. Fibers were aligned parallel with the direction of the contact line receding and the molecules of IIDDT-C3 adopted an edge-on orientation with the backbone parallel with the direction of fiber long axis. The p-p stacking distance between adjacent molecules was 3.63 ？.