二元高揮發性液滴於加熱基板上的蒸發擴展過程在噴墨列印、噴霧冷卻技術與電子散熱等工業應用中十分常見。此現象牽涉流體動力學、熱傳遞、相變化、質量傳輸與移動接觸線力學等複雜的交互作用。本研究的核心在於探討基板溫度對液滴蒸發擴展行為的影響，以及詮釋在實驗中發現新的擴展階段之物理現象、基板溫度與液滴接觸直徑的非單調變化。透過建構二維軸對稱模型進行數值模擬，並採用 ALE 方法追蹤液滴幾何外型變化，模型中引入蒸發冷卻效應以觀察高揮發液滴對液滴擴展過程中的影響、透過複合動態接觸角模型建立移動接觸線的動態力學，並建立能預測二元液滴的靜態接觸角的模型，以精準的預測實驗所觀測的現象。結果顯示，除了文獻中提及的慣性與黏性擴展階段，本研究指出由於異丙醇的高揮發性引發在液氣介面出現較大的濃度梯度，並進一步在三相接觸線附近出現溶質馬蘭哥尼流。此溶質馬蘭哥尼應力成為新的液滴擴展驅動力，本研究稱此階段為馬蘭哥尼擴展階段。本研究亦發現靜態接觸角會隨甘油濃度增加而上升，靜態接觸角的上升會成為液滴擴展的阻力，並得出馬蘭哥尼擴展階段是驅動力（溶質馬蘭哥尼應力）以及阻力（動黏滯係數與靜態接觸角隨甘油濃度增加而上升）之間的抗衡階段。;Evaporative spreading of binary highly volatile droplets on heated substrates is ubiquitous in industrial applications such as inkjet printing， spray cooling technology， and electronic cooling. This phenomenon involves complex interactions including fluid dynamics， heat transfer， phase change， mass transport， and moving contact line mechanics. This study investigates the effect of substrate temperature on the evaporative spreading behavior of droplets， as well as interpreting the physical phenomena of a newly discovered spreading stage in experiments， along with the non-monotonic variations between substrate temperature and droplet contact diameter. A two-dimensional axisymmetric model is developed using the Arbitrary Lagrangian-Eulerian (ALE) method to track the liquid-gas interface of the droplet， incorporating the evaporative cooling effect to observe its impact during the spreading process of highly volatile droplets. Furthermore， the moving contact line dynamics are established through combined dynamic contact angle model， complemented by a predictive model for the static contact angle of binary droplets. The results indicate that， in addition to the inertial and viscous spreading stages mentioned in the literature， this study points out that the high volatility of isopropanol induces a large concentration gradient along liquid-gas interface， which further triggers a solutal Marangoni flow near the three-phase contact line. This solutal Marangoni stress serves as a new driving force for droplet spreading; hence， this study terms this stage the “Marangoni” spreading stage. This study also reveals that the static contact angle increases with the concentration of glycerol; therefore， the increase in the static contact angle also acts as a resistance to droplet spreading. Consequently， it is concluded that the Marangoni spreading stage is a counterbalancing stage between the driving force (solutal Marangoni stress) and the resistances (the increase in viscosity and the static contact angle).
