## 3 Results and Discussion
### Flow Rate  
The results of the mass flow rate distribution in each model were summarized from the simulation, as shown in Figure 7. The changes in blood flow over time in the LCX, LAD, and DB branches during a complete cardiac cycle are recorded in Figure 7a-c, respectively. From the observation data, it was not difficult to find that regardless of the plaque distribution model, the flow changes in each branch during systole and early diastole were almost the same, and there was no obvious change. However, the flow rate fluctuated significantly at the outlet in the late diastole. The changes in branch flow in the late diastole of each model were compared. In Model 1, the flow rate was relatively moderate at the LCX and LAD branches, while the flow rate was relatively high at the DB branch. In Model 2, the flow rate was relatively high at the LCX branch, while the flow rate was relatively low at the LAD and DB branches, and the flow rate at the DB branch was significantly lower than the other models. In Model 3, the flow rate distribution was diametrically opposed to Model 2, with a lower flow rate at the LCX branch and a higher flow rate at the LAD and DB branches. In Model 4, the flow rate was relatively low at the LCX and LAD branches, while the flow rate was relatively moderate at the DB branch. The average flow rate of each branch in the different models is summarized in Table 1. About half of the blood flow came out of the LAD, with most of the rest coming out of the LCX and a small portion out of the DB. The distribution of blood in the left coronary artery was consistent with the clinically observed data [15]. We observed the average flow of each branch and the percentage of the branch flow to the total flow. The flow of a branch in the late diastole determined the average flow of the branch. Intuitively, the location of the plaque had an impact on the distribution of the blood flow in each branch. When the plaque was close to the side of the heart, the blood flow distribution was significantly different from that of other plaques, and the difference in flow distribution between plaques at the other locations was not significant. When the plaque was on one side of the heart, blood flow to the LCX branch increased, while blood flow to the DB and LAD decreased compared to the other plaque locations. Figure 6: Curve of maximum VMS under a complete cardiac cycle. The influence of the circumferential distribution of plaques on the velocity was further analyzed, and the streamline distribution of each model during the peak contraction period was obtained after postprocessing, as shown in Figure 8. Since the circumferential distribution of the plaque will change the magnitude and direction of blood flow velocity, in addition to the velocity at the LAD and LCX sections, the section velocity at the LM was also obtained, as shown in Figure 9. The maximum velocities, mean velocities, and velocity standard deviations for the three cross-sectional locations during peak systole and late diastole are summarized in Table 2. It can be observed that the flow velocity increased sharply at the plaque, and there was a clear vortex behind the plaque. For convenience of observation, the plaque area was enlarged and rotated at a certain angle in the figure. It can be observed from Figures 8 and 9 that during the peak systolic period the velocity distribution at the LM section was greatly affected by the circumferential position of the plaque. The narrowing of the blood flow channel was due to the presence of the plaque, which caused an increase in the blood flow velocity. In the different models, the maximum speed was inconsistent, and there were obvious differences. The different distribution