We report particle image velocimetry measurements of the collision of a vortex ring with a heated
wall kept at constant temperature. We consider the case when both the vortex ring and the thermal
boundary 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 vortex
ring grows in diameter while approaching the wall and therefore it sweeps progressively an
increased surface on the wall. siid A boundary layer-driven stage, where the vortex ring moves
upward due to the thermal convective motion generated by the heated wall. In some cases, the
head-on collision triggers the rings azimuthal instability as revealed by the formation of vortical
structures arranged on a wavy starlike pattern and confirmed by flow visualizations. A single
collision generates important velocity gradients and shear stresses along the wall accompanied with
the creation of local vorticity normal to the vertical heated wall. Peak wall shear stresses occur near
the point of impact of the vortex ring core. 德国LaVision PIV/PLIF粒子成像测速场仪 三维立体PIV Imager sCMOS PIV相机
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