Effects of spatial disorder on the transition to Taylor vortex flow

Using particle imaging velocimetry (PIV), we investigate the effects of fix ed spatial disorder in a Taylor-Couette system near the onset of Taylor-Vor tex flow. We induce small spatially frozen variations in the local control parameter of the system by varying the radius of the inner cylinder along t he cylinder axis, y. For a smooth inner cylinder the bifurcation to Taylor vortex rolls is instrumentally sharp. With a 12% variation in the local Rey nolds number Re(y) we find localized rolls with an amplitude that varies ex ponentially in the spatially averaged Re. Smoothed bifurcations and localiz ed flows have been seen in recent numerical studies of systems with spatial ly varying control parameters and in convection of a fluid in a porous medi um. The secondary transition to wavy how is significantly elevated in the s ystem with spatially varying Re(y).