平板上共振液滴之固化

Abstract

本研究旨在觀察平板上液滴的各個共振模態受加速度、頻率的影響，並嘗試使用低溫流體進行急速固化以保存瞬間的共振外型。本研究使用金屬鎵作為實驗流體，並用環狀 LED 作為光源，再由液滴反射的光環形狀判別共振的外型。本研究成功觸發 16 種已被發現的共振模態。其中有 2~8 邊形的 sectoral、4 種 zonal 和 5種 tesseral 模態。除這 16 種模態之外，本研究還觀察到多種振幅不固定的不穩定大振幅模態以及伴隨 2~4 邊形的'跳躍'模態。本研究發現到 sectoral 模態的振幅與頻率成呈負三次方的關係，且觸發各 sectoral 模態所需要的受力是固定的，並不會受液滴體積變化而改變。本研究發現到共振液滴固化時的過程與固化完的形狀因液滴共振振幅與不同液體而有所不同，並不會受共振模態影響。然而，實驗與計算結果皆顯示，固化時間比預期時間長上許多。因此，我們無法使用急速固化的方式保存液滴的共振外型。

This research is trying to find out the influence of the acceleration and the frequency of a sessile resonating drop. Also, this research is trying to maintain the resonance shape of the drop by using cold fluid to freeze it. The experimental fluid is gallium. We used aLED halo as the lighting method. From the reflection of the halo on the surface of the drop, we could tell the shape of the resonating drop. In this research, we found 16 modes which had been found before, including 7 sectoral modes, 4 zonal modes and 5 tesseral modes. In addition to these 16 modes, we also found several unstable sectoral modes which don’t have the same amplitude in every crest, and 3 jumping modes with different polygon shapes. We found the relation between the frequency and the amplitude. The experiment result shows that the force thresholds of sectoral modes are independent of the volume of the drop. In other words, if the volume of the resonating drop increases, the minimum force to trigger the specific sectoral mode will still be the same. We found that the shape of the solidification drop depends on fluid and the wave amplitude, not the resonance mode. Additionally, the experiment and the calculation results show that it’s impossible to maintain the resonance shape by using solidification.