近年來，由於氣候變化的影響，極端氣候的現象比過去更為頻繁，如:暴雨、強風、颱風...等，由於考慮到圓柱結構放置在戶外的情況下，我們在設計外型的階段時必須將惡劣氣候的條件考慮進去。因此，對於在大雨影響下柱體尾流情形的數值模擬更為重要且不可忽視。利用商用軟體FLUENT於不同數量和外型的柱體和大雨機制的模擬。 在此篇論文中，我們首先對於在雷諾數為100和200流體流經單一圓柱後的尾流分離做數值模擬。接下來，在對於雷諾數為200的情況下兩個相同直徑前後串聯的圓柱做模擬。透過成功的模擬前面3個不同的情況，我們對於接下來的研究更有信心。模擬雷諾數為2.5×104~1.0×105的LP-810纜線在大雨下的情形，則是採用FLUENT內二相流(Two-Phase Flow)的DPM模組(Discrete Phase Model)和改變圓柱的表面出糙度來計算空氣動力特性。雖然模擬出的結果和實驗值不完全相同，但是我們成功的模擬出LP-810在晴空狀態及大雨影響下阻力係數的變化趨勢。本研究在對於工業用纜線在側風及大雨影響條件下的空氣動力特性分析是非常有用的。 In recent years, due to the impact of climate changing, the phenomenon of extreme weather is more frequently compared to the past, such as heavy rain, strong wind, typhoon-weather conditions etc. For the cylindrical structure being located outdoors, we must put these severe weather influences into considerations in the stage of geometry design. Therefore, the importance of numerical simulation for circular cylinder vortex flow under the heavy rain effects can never be neglected. In this work, we first investigated the vortex shedding behind a circular cylinder at Re=100 and 200. Secondly, two circular cylinders in tandem arrangement at Re=200 are simulated also. Through the simulation of these three cases successfully, we will be more confident for the following research. For the heavy rain simulations, the two-phase flow approach plus the wall film mechanism on the body surface are implemented for LP-810 cable and at Re=2.5×104 to 1.0×105. Although the numerical results for the cable under the heavy rain effects show that aerodynamic degradation was not perfectly match to the experimental data, the correct tendency of the cable aerodynamic performance under both the clear weather and heavy rain situations are simulated successfully. The proposed simulation results will be quite useful to understand the industrial suspension cable’s behavior in cross wind and heavy rain conditions.
