• 作者： Su, Yuan-Yuan
• 中文摘要： 本研究利用線性穩定度分析,探討平板流中n層黏彈性流體之界面穩定度問題。首先採用長波漸近技巧來建構參數之穩定臨界區域。結果顯示,將黏度高之流體置於平板中心有助於界面波之穩定。同時,純彈性穩定度分析之結果顯示,穩定度不僅取決於較富彈性流體所置之位置且取決於個別流體所佔之體積百分比。唯有將較厚且較具彈性之流體置於中心層,才可獲得全波數界面波之穩定度。由於任一波長的擾動波皆可能導致界面不穩定度,因此數值方法被採用,以探討黏彈性流體全波長擾波之穩定度問題。分析結果顯示,將較高黏度且較具彈性之流體當作中心層將可穩定任一波長之界面波。
• 英文摘要： This work analyzes the linear stability of n-layer viscoelastic fluids in the channel die flow. The long wave asymptotic technique is employed to construct the critical parameter space. Our results indicate that having fluids of a higher viscosity as the core layer stabilizes interfacial waves. According to pure-elastic stability analysis, stability is determined not only by the location of the more elastic component but also by the volume percentage of the individual component. Only when the more elastic and thicker fluid is located in the core layer can the stability for the spectrum of all wave numbers be attained. The dominant mode of interfacial instability can be attributed to disturbances of arbitrary wavelengths. Hence, the eigenvalue problem for any disturbance wave number is also solved by using pseudospectral methods. Numerical results indicate that arranging the more viscous and less elastic component as the core layer can stabilize the spectrum of all wave numbers.
• 中文關鍵字： 多重界面; 穩定度; 黏彈性; 平板流動
• 英文關鍵字： Multiple Interface; Stability; Viscoelasticity; Channel Die Flow