Finite Area regression in 2306 leads to error in the avalanche module

Summary

I ran the wolfsgruben case with v2306 and experienced some artifacts that were not there in v2212. I tried different combinations of versions of OpenFOAM and the avalanche module and came to the conclusion that the regression is in OpenFOAM-v2306.

Steps to reproduce

Run the wolfsgruben tutorial of the OpenFOAM avalanche module. Note that there are some missing semicolons in the releaseArea file (I already prepared a patch for 2312 to fix that).

What is the current bug behaviour?

When the flow depth becomes small, the velocity starts to look weird (see image below).

What is the expected correct behavior?

The velocity looked smooth at this position with v2212.

Relevant logs and/or images

finiteArea_v2306

Environment information

• OpenFOAM version : v2306
• Operating system : Linux Mint 21
• Hardware info : AMD Ryzen 7
• Compiler : gcc

Possible fixes!

I expect some changes, maybe in the definition of fac::grad. Maybe some changed signs?