We report particle image velocimetry measurements of the collision of a vortex ring with a heatedwall kept at constant temperature. We consider the case when both the vortex ring and the thermalboundary layer generated by the vertical heated wall are stable and laminar prior to any interaction.The impingement process can be divided into two parts. sid A ring-driven stage, where the vortexring grows in diameter while approaching the wall and therefore it sweeps progressively anincreased surface on the wall. siid A boundary layer-driven stage, where the vortex ring movesupward due to the thermal convective motion generated by the heated wall. In some cases, thehead-on collision triggers the ring’s azimuthal instability as revealed by the formation of vorticalstructures arranged on a wavy starlike pattern and confirmed by flow visualizations. A singlecollision generates important velocity gradients and shear stresses along the wall accompanied withthe creation of local vorticity normal to the vertical heated wall. Peak wall shear stresses occur nearthe point of impact of the vortex ring core.
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