PIV, integrated with a suitable triggering device such as a hot-wire probe (isothermal), pressure transducer (hot), enables efficient generation of temporally-resolved planar flow fields. There is considerable time benefit in using a planar characterisation technique such as PIV in this instance, as it is now easier to build fully 3-dimensional plots of these complex structures by systematically traversing downstream. However, phase-locked laser Doppler anemometry (LDA) has many advantages and is often complementary to PIV for phase-locking purposes.