## 3 Results
### Model Validation
#### 3.1.2 Experimental Validation  
To verify the accuracy of the proposed method, we compared the computation results with the experimental results and the results of the implicit function and level set methods only. Firstly, the transient temperature at two points of the potato was measured by using an optical fiber thermometer. The initial position of the potatoes is shown in Figure 10d. Figure 12 shows the comparison of results between the two computation methods (the proposed method and implicit function and level set methods only) and the experiments. The two points of the temperature measurement are located on the upper surface of the potato, and their positions are indicated in Figure 12a,b. The results show that the points' temperature computed by the proposed method is more consistent with the experiment, and the error computed by the implicit function and level set methods is only within an acceptable range. Through the comparison of points temperature, the accuracy of the proposed method is verified, and the results show that the proposed method's accuracy is better than that of the implicit function and level set methods only. Figure 11: The \(S_{11}\) computed by the proposed method and the discrete positions (potato’s size: \(35\) mm \(\times\)\(35\) mm \(\times\)\(10\) mm). Figure 12: Comparisons of experimental and computed temperature at 2 points (two points located at the upper surface of the potato, \(v_{p}\) = 3 mm/s, \(\omega_{0}\) = \(\pi\)/10 rad/s, input power: 100 W). (**a**) Point 1 is located at \(x\) = 10 mm and \(y\) = 17.5 mm. (**b**) Point 2 is located at \(x\) = 17.5 mm and \(y\) = 10 mm. Second, we compared the computed temperature distribution of the potato with the experimental results. The temperature distribution on the potato's upper surface is shown in Figures 13 and 14, and we compared the surface temperature distribution of the potato's upper surface with the proposed method, the implicit function and level set methods only and the experiment. In Figure 13, the temperature distribution on the potato's upper surface obtained in the experiments is \(x\)-\(y\) axisymmetric, which is consistent with the results computed by the proposed method. However, the temperature distribution on the potato's upper surface computed only by the implicit function and level set methods do not present such a symmetrical pattern. Moreover, it is noted that the temperature at the center of the temperature distribution on the potato's upper surface computed by the proposed method is lower than the surrounding area, presenting a circular area of low temperature. The experimental results also show that the temperature at the center is lower, but the cold spots are not too concentrated compared with the proposed method. The reason for this may be that it takes about 5 s for the microwave-heated potatoes to be taken out of the microwave cavity to take a picture of the temperature distribution with a thermal imaging camera during the experiment, which causes the potato temperature distribution to diverge. From the temperature value, the results of the experiment are lower than the temperature value of the computation results. The possible reasons for this phenomenon in the experiment are mainly due to the following reasons: (1) the initial temperature of the  
Figure 14: Comparisons of temperature distributions on the potato’s upper surface are made between computational results and experiments after 20 s of motion (input power = 100 W, unit: \({}^{\circ}\)C, \(v_{p}\) = 3 mm/s, \(\omega_{0}\) = \(\pi\)/10 rad/s): potato size: 25 mm \(\times\) 25 mm \(\times\) 10 mm, initial center point locates at (\(-\)0.025, 0) (unit: m). (**a**) Implicit function and level set methods only. (**b**) Proposed method. (**c**) Experimental Sample 1. (**d**) Experimental Sample 2.