 # 英文论文代写 Thermal Counterflow Past A Cylinder

## Find how long does the vortices stay close to the initial locations

The task that now is in process is to find how long that the vortices stay close to their initial locations. The main idea is to make the time – dependent graphs for each case and then see where the line on the graph goes away from the initial location. To do this the data cursor can be used in Matlab but this will take too much time and won’t be enough accurate. The basic idea is to set a range of tolerance on the graph and when the line goes out of these limits (upper and lower limit) the program will stop and give the time at this point. This time will be the time that the vortex point is close to its initial location. In figure 7.1 below is an example of this idea where are showing the upper and lower limit.

Figure 7.1: Time – dependent trajectories of the two vortices case x1(t).

The m – file that was made to find this time point is ready and is like the Motion2downp.m (Appendix 1). This program sets the upper limit, for example 30% of the initial location and lower limit the same. Then at each time point it compares the location and if it is smaller than upper limit and bigger than lower limit the program continuous to the next time point, if it exceeds the limits the program stops and gives the time at this point. This is the non – dimensional (t1) time which the vortex point was close to its initial location. To find the dimensional time (t) the following formula will be used:

(7.1) where a is the disk radius and U is undisturbed flow velocity.

M文件是找到这个时间点准备，就像motion2downp M（附录1）。本程序设置了上限，例如30%的初始位置和下限相同。然后在每一个时间点，它比较的位置，如果它是小于上限和大于下限的程序连续到下一个时间点，如果它超过了限制程序停止，并给出了在这一点上的时间。这是非维（T1）的涡点接近其初始位置。要找到的维时间（t）下列公式将被使用：

（7.1）其中A是磁盘半径和U是不受干扰的流速。

## Conclusion

Now the project is going with respect to Gantt chart on page 3, the matlab code is working correct and the next task is to interpret the solution and compare the results with Zhang and Van Sciver experiment. Then to make the final report, the poster and prepare for the presentation at the end of the semester in the time as is shown in the Gantt chart