• 作者： 林貫中
• 作者服務機構： 中興大學應用數學系
• 中文摘要： 本文推導一模式以分析軸對稱黏彈薄膜非線性行為。此模式包含之物理效應有表面張力、重力、黏滯力、慣性力、彈力、及黏彈模式之材料特性。 在穩定流情況下，由數值解及解析解可得到弱黏彈薄膜由於受重力其半徑由出口直接銳減。若反重力方向則只能達一定高度，此高度和Tuck（1982）解一致。當考慮黏滯薄膜時，速度場之解析解和Brown之實驗值非常接近。當黏彈效應顯著時，由於預壓力、半徑與厚度皆增至一定值，此定值與預壓力相關而和重力無關。當有重力時，半徑增至最大值後受重力影響遞減。
• 英文摘要： An approximate model for axisymmetric viscoelastic thin annular curtains is derived The annularcross section is thin in the sense that the thickness is much smaller than the mean radius. This modelincludes the physical effects of surface tension, gravity, viscosity, inertia, elasticity, relaxation time andproperties of the viscoelastic fluid material on the motion. To investigate the features of steady viscoelastic annular concentric circular free curtains, theanalytical and numerical results of variation of thickness and mean radius are presented. For a weaklyviscoelastic fountain curtain,the height is finite. This height agrees with the result by Tuck (1982). Also,the mean radius is drawn down directly from the nozzle exit under gravity. The results of the axial velocityof viscous curtains show good agreement with experimental results by Brown (1961). For a viscoelasticfluid, if unrelaxed stress states exist at the nozzle exit and the gravity effect is excluded, then the meanradius is usually released from the nozzle exit and increases to a maximum (or minimum) constant value.The thickness also increases proportionally to the value of the mean radius. For a viscoelastic fluid includingthe gravity effect, the mean radius increases to a maximum value and then decays under gravity.
• 中文關鍵字： viscoelastic liquids; annular curtains; gravity
• 英文關鍵字： --