*2.2. Geometry*

Three-dimensional model is built to investigate the erosion–corrosion process of elbow. Figure 2 shows a planar graph of the 90◦ elbow with two straight sections, four featured edges and two featured surfaces (without size scale). The lines with color are used to indicate the feature edges of the tube and analyze the process of erosion–corrosion. The diameter (*D*) of pipeline is 600 mm. A curvature ratio of elbow, which is the ratio of a curvature radius of the centerline to that of interior edge of the elbow, is 1.5 (dimensionless). Flow is input into the first straight section (*L*<sup>1</sup> = 3000 mm) in length at the top

left corner of the figure, with a 90 ◦ elbow section and the second straight section of pipe (*L*<sup>2</sup> = 3000 mm) in length in sequence.

**Figure 1.** Schematic of chemical equipment.

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**Figure 2.** Schematic diagram of pipeline.
