三維自由液面水流撞擊物體之流場模擬與分析

Simulation and analysis of three-dimensional free-surface flows impacting on objects

陳昭昇(Chen-Chang Sheng)

指導教授 ： 鄧志浩

中原大學/工學院/土木工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000516

摘要

摘要
本文以數值方法模擬三維自由液面撞擊障礙物之水流的流況分析，利用最小平方有限元素法(LSFEM)求解不可壓縮流場所產生的自由液面的變化，使用固定網格，以流體體積法為基礎配以一連續函數在此稱之colour function；將密度視為一個連續函數的變化對自由液面問題進行數值模擬。
文中將模擬數種不同有關潰壩的模式，並進行驗證及比較，首先驗證簡單三維潰壩，並與Martin and Moyce(1952)的實驗數據比較；並且於潰壩流場之下游放置一道橫向的牆面，使潰壩後之水流產生撞擊並與Koshizuka, et al., (1995)之實驗結果做比較；接著模擬於下游放置一突起之方塊及一長柱狀體兩種潰壩模式，並觀察水流在撞擊後產生的自由液面的變化，發現利用最小平方有限元素法所得的結果與其他文獻相符合，可明確的以三維模式顯示出潰壩後自由液面的變化情形。

關鍵字

最小平方有限元素法 ； 自由液面 ； 潰壩

並列摘要

ABSTRACT
This research studied the numerical simulation of three-dimensional free-surface flows impacting on objects. The Least-square finite element method (LSFEM) is adopted for the numerical simulation of the incompressible free-surface problems. Using a fixed grid and based on a volume of fluid method by a continuous function which called colour function, the density change as a continuous function on the numerical simulation of free-surface problems.
The paper will simulate the dam-break flows of several different setups. First the simple three-dimensional dam break flow will be compared with experimental data of Martin and Moyce (1952). And then a horizontal wall at the downstream field, the dam-break flow impact on the wall will then be simulated and compared by the results with Cheng (2003). The same as above setup, the other objects like the box and a long cylindrical body are set in the channel to observe the free surface variations after a collision. It is found that the Least-square finite element method can get the same results as those from other literature and can be applied for the simulation of the three-dimensional free-surface flows simulation.

並列關鍵字

dam break ； Least-square finite element method ； free-surface

參考文獻

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