In this section, in order to investigate the characteristics of parallel efficiency, the magnetic field analysis was performed with various number of divisions of the analysis region.

shows the discretization data. In order to investigate the performance of parallel computation, the analysis is performed under the condition that the number of parallel is 600 to 9600. The number of elements of the finite element model is approximately 340-380 million. The number of elements, nodes, and edges of the analysis model increases as the number of parallel increases, because the overlapping elements [4] increase.

Table 3 Discretization data (tetrahedral element)

Figure 2 shows the elapsed time. The calculation time is approximately 400 minutes when number of parallel is 600 and that is approximately 30 minutes when number of parallel is 9600.

Figure 3 shows the speed-up. The calculation time of 1 division is calculated from the elapsed times of 600 and 9600 divisions by Amdahl’s law. From Figure 3, we can see that the speed-up close to the ideal can be obtained when number of parallel is 2400 or less. The speed-up falls below the ideal as the number of parallel increases.

Figure 4 shows the parallel efficiency. The parallel efficiency is over 90% when number of parallel is 1200, and that is over 70% even when number of parallel is 9600.

Figure 4 Parallel efficiency

From these results, we confirmed that using parallel computation by *K computer*, we can analyze the electromagnetic field of the wireless power transfer system in a wide area within a practical time. Moreover, it is confirmed that the electromagnetic field can be calculated with high efficiency even if the number of parallel is increased.

## Comments (0)

General note:By using the comment function on degruyter.com you agree to our Privacy Statement. A respectful treatment of one another is important to us. Therefore we would like to draw your attention to our House Rules.