Possible mechanism for transitions in wavy Taylor-vortex flow

We studied a sequence of transitions between wavy-vortex-flow states with $m=3\mathrm{}$, in which a vortex pair was gained or lost. We found that the local-vortex pair width $\lambda$ became nonuniform as the Reynolds number was increased. Transitions occurred when the local $\lambda$ was larger (smaller) near the center (ends) than the stability limit for the underlying Taylor vortex flow, extrapolated into the wavy-vortex-flow regime.