you can try to calculate something like a local winding number for example.
For each vertex get the neighbour vertices +- a number, like (…,vtx - 2, vtx - 1, vtx, vtx + 1, vtx + 2,…). Next step is to calculate the local center of these neighbours. After this you can use the center to loop over the vertices and accumulate over the angles. The angles should be big near the curls.
Here is an example (using some wrangles). The result attribute is a vertex attribute called @w. This can be used to determine the local curl. But the results will strongly depend on the input (like local vertex density, planarity etc …).
