Distinguish High Angle and Low Angle GB and Assign different diffusivities or other grain parameters

[Linwitness]

Reason

The element diffusion will be affected by Grain Boundary (GB) type: It diffuse faster in High Angle GB (HAGB) than in Low Angle GB (LAGB). The distinguishing of the two GB types can increase the diffusion model accuracy.

Design

The feature include two phases. In the first phase, a grain growth simulation will distinguish the GB type based on the misorientation from EBSD data and smooth the sharp GBs. As the following figure shown, LAGB is assign "1", HAGB is assign "2", and the Triple junction is assigned an interpolated value. In the second phase, a diffusion simulation will build the "bnds" for different GB types from the result of first phase. Then, we can use the different "bnds" to assign the continuous local diffusivity.

Impact

With the new feature, MOOSE can read the EBSD data and derive the local diffusivity or other grain parameters. Also, the more accurate effective diffusivity from the feature can be used to evaluate the influence of grain structure, like different grain size, aspect ratio, and the percentage of HAGB.