Tuft
From Wikipedia, the free encyclopedia
A tuft is a strip of yarn or string of varying length taped or glued to a surface as a technique for flow visualization. Tufts have been commonly used in aeronautics to study air flow direction, strength, and boundary layer properties.
The world's largest bed of tufts (61 feet by 61 feet) was created at NASA Ames Research Center to study air flow fields involving a helicopter's rotor disk.[citation needed]