tortuosity

The word tortuosity (adjective: tortuous) indicates the quality of a curving object of having many curves and/or twists. It can be used to describe the path of a river, and is sometimes used to describe the channels through a porous material. Some measures have been devised to quantify it, necessarily adopting a more specific definition, probably adapted to a specific type of issue. One (simple) measure:

τ = L/C

• τ - tortuosity (in this case, arc-chord ratio).
• L - length of the curve (i.e., arc length).
• C - straight-line distance between the ends of the curve.