Effects of spatial disorder on the transition to Taylor vortex flow

Using particle imaging velocimetry (PIV), we investigate the effects of fixed spatial disorder in a Taylor-Couette system near the onset of Taylor-Vortex flow. We induce small spatially frozen variations in the local control parameter of the system by varying the radius of the inner cylinder along the cylinder axis, y. For a smooth inner cylinder the bifurcation to Taylor vortex rolls is instrumentally sharp. With a $12\%$ variation in the local Reynolds number Re(y) we find localized rolls with an amplitude that varies exponentially in the spatially averaged Re. Smoothed bifurcations and localized flows have been seen in recent numerical studies of systems with spatially varying control parameters and in convection of a fluid in a porous medium. The secondary transition to wavy flow is significantly elevated in the system with spatially varying Re(y)