INSTABILITIES OF THE SIDEWALL BOUNDARY-LAYER IN A DIFFERENTIALLY DRIVEN ROTATING CYLINDER

We report experiments on the instability of the sidewall Stewartson la yer that arises in the fluid next to the vertical boundary of a cylind er that is rotating about its axis at rate Omega, and is driven by slo w differential rotation of a contact lid. There are three primary inst abilities that come in sequentially as the driving is increased: verti cally traveling axisymmetric rolls, quasistationary diagonal rolls inc lined backward (retrograde, or opposite to the direction of the basic rotation Omega) with height, and prograde-traveling waves that tilt fo rward with height. These instabilities are markedly different from tho se observed in laboratory studies or computational simulations of pres sure-driven flow down a rotating channel. The instability mechanisms a ppear to be related to our particular method of driving these flows. ( C) 1996 American Institute of Physics.