Wind Tunnel Studies of Ripple Formation

ABSTRACT

A wind tunnel of recirculating type was constructed and used for the study of eolian ripples. The height and wave-length of the ripples were found to be a function of wind velocity. There is a ripple formation period, the length of which depends on wind velocity. During this time fully developed ripples form. After that threshold time ripples are almost stable in size and form except at the high wind velocities which produce “secondary” ripples on the surface of the “primary” ripples and thus cause a decrease in mean wave-length. Material sorting on the rippled surface was studied as well as the migration rate of the ripples. At the beginning of ripple formation a process of sorting of the sand material was found.