Existence Conditions and Formation Process of Second Type of Spiral Loop Particle Accumulation Structure (SL-2 PAS) in Half-zone Liquid Bridge

We focus on unique phenomena known as particle accumulation structure (PAS), especially on the conditions of the existence for second-type spiral loop PAS (SL-2 PAS) and on their formation processes under normal gravity. We investigate the existence conditions as functions the aspect ratio of the liquid bridge and the Marangoni number, the intensity of the thermocapillary effect. We discuss the differences among SL-1 PAS, SL-2 PAS and the flow field without PAS through observation of the solid-like structures of the PAS in a rotating frame of reference with the hydrothermal wave, and through monitoring of the surface temperature by infrared camera. We evaluate the formation time of PAS by employing a modified accumulation measure by considering the effect of the particles' size.