液滴之擴展行為在噴墨列印與電子元件塗層等多項應用中扮演關鍵角色，其動態行 為與內部流動機制將直接影響實際應用之品質與效率。當基板被加熱時，液滴所受之蒸 發冷卻效應與馬蘭哥尼效應將對其擴展行為產生顯著影響，並可能導致擴展過程受到抑 制。為深入探討此一現象，本研究系統性分析不同基板溫度條件下液滴內部流場之轉換 行為與流速變化。 實驗中使用三種甘油–水溶液濃度（30、40、50 wt%）與四種基板溫度（27、40、 50、60 °C），並結合聚苯乙烯螢光粒子與高速攝影技術，針對液滴擴展初期（一秒內） 進行流場顯影與分析。研究結果顯示，相較於低溫基板（27、40 °C），高溫基板（50、 60 °C），初期階段液滴回彈振盪時期略為延長，而後期階段能誘發更強烈之馬蘭哥尼回 縮現象，有效抑制液滴的擴展行為。;The spreading behavior of droplets plays a critical role in various applications such as inkjet printing and electronic component coating. The dynamics and internal flow mechanisms of droplets directly affect the quality and efficiency of these processes. When the substrate is heated, evaporative cooling and Marangoni effects significantly influence droplet spreading and may suppress the spreading process. To gain a deeper understanding of this phenomenon, this study systematically analyzes the transition of internal flow patterns and velocity changes in droplets under different substrate temperature conditions. Experiments were conducted using glycerol–water solutions at three concentrations (30, 40, and 50 wt%) and four substrate temperatures (27, 40, 50, and 60 °C). Polystyrene fluorescent particles combined with high-speed imaging were employed to visualize and analyze the flow field within the first second of the droplet spreading process. The results show that, compared to low-temperature substrates (27 and 40 °C), high-temperature substrates (50 and 60 °C) prolong the initial droplet oscillation and rebound phase, and subsequently induce stronger Marangoni backflow, effectively suppressing droplet spreading.
