# Study on Microwave Deicing of Carbon-Fiber-Modified Concrete under Multi-Factor Coupling Effect
## 4 Simulation Experiment  
In order to facilitate the computer simulation calculation, some unnecessary factors are simplified and assumed in the simulation process. The specific simplified conditions and assumed conditions are as follows:  
1. Thermal convection between ice and air is not considered. According to the theoretical analysis, the thermal convection between the ice layer and air is very limited, so it can be ignored. However, a boundary condition needs to be set for the thermal convection between the water layer and air after ice breaking. That is, after the ice is broken, the air is a poor conductor to the water layer. 2  
Based on the above three constraints, the constructed model can simulate the wave-absorbing heating process of different materials by changing the electromagnetic parameters of channel materials, simulate the ice thickness in a real environment by changing the ice thickness and can be used to simulate the microwave heating process without ice when the ice thickness is 0. The actual conditions of different microwave sources and the external environment are simulated by adjusting the height and initial temperature. Open space can be used for simulation of an absorbance model with different materials, different heights, different thicknesses of the ice and different initial microwave temperatures. The simulation adopts a perfectly matched layer boundary and can therefore basically describe open space under the ice without a change in ice thickness and with a single microwave source. The parameters of the model are shown in Figure 12: the size of the waveguide is 5.46 \(\times\) 10.92 \(\times\) 15 cm. The dimension parameters of the bell mouth are as follows: vertical wall height, oblique wall height, bottom opening width. The ice layer is 50 \(\times\) 50 \(\times\) 5 cm, and the concrete specimen is 50 \(\times\) 50 \(\times\) 5 cm. The height of the bell mouth from the concrete surface is measured in 15 cm. The size of the air environment is 100 \(\times\) 100 \(\times\) 100 cm, and an impedance matching layer is added to the outer edge of the air. Under the condition of no ice layer, the heat absorption efficiency of a concrete specimen with a height of 20 mm, 40 mm and 60 mm is simulated. The simulation results are as follows. Under the condition of no ice layer, the heat absorption efficiency of a concrete specimen with a height of 20 mm, 40 mm and 60 mm is simulated. Figure 13 shows a geometric model diagram of different trumpet heights and a temperature distribution diagram of the concrete specimen surface after 90 s heating. According to Figure 13: (1) There is an obvious heating area on the concrete surface with a roughly oval shape, and the size of the heating area is similar to that of the trumpet. This shows that microwave can heat concrete and generate heat and that there is a clear area of heat generation. (2) The temperature increase at the central point (T\({}_{0}\)) in the heating region is the highest, and the farther away from the central point (T\({}_{0}\)), the lower the temperature increase. This shows that microwave heating is radiative, so multiple microwave sources can be used for channel heating to achieve multi-wave source coupling heat generation. (3) When the height is 20 mm, the area of the concrete surface temperature increase reaches 317.2 cm\({}^{2}\). Compared with a concrete surface area of 103.9 cm\({}^{2}\) in the test group with a height of 60 mm, the overall temperature increase area of the concrete surface decreases by 67.24% when the height is increased by 40 mm. Figure 12: Schematic diagram of simulation grid construction. Ice-water phase change material is installed on the surface of the concrete, and the wave-absorbing and deicing performance of concrete specimens at heights of 20 mm, 40 mm and 60 mm is studied. The corresponding surface temperature distribution diagram of concrete is obtained (as show in Figure 13).