- 期刊
- OpenAccess
Numerical Computation of Two-Phase Flows
二相流之數值計算分析
摘要
本文運用數值方法分析二相流問題，首先利用有限體積法以離散控制方程式，接著使用流體體積法計算在網格單元間不同流體之分佈，爲能準確地計算自由液面形狀，採用界面補捉模型以求得流體分量傳導項，同時以等效流體觀念處理位於同一網格單元內之不同流體。首先計算因強制運動所引起之方形水槽內流體沖激問題，計算結果顯示數值模擬能處理相當複雜之自由液面形狀；接著研究流體波擊現象，驗証其最大壓力發生在接近自由液面處；而在探討液滴撞擊液膜之行爲模式上，數值結果與實驗量測相較，有相當一致的趨勢，在分析單一上升氣泡於二維氣泡床之流場特性，發現表面張力與黏性力的大小對氣泡之形狀與尾流場有決定性的影響，最後探討船船興波問題，計算之興波阻力與水糟試驗結果比較，兩者相當接近。
並列摘要
The prediction and simulation of some two-phase flow problems are demonstrated in this paper. The applied numerical scheme is based on a finite volume formulation to solve the Navier-Stokes equations, and a volume-of-fluid approach to determine the fluid front. An interface-capturing scheme is employed in order to preserve sharpness and to avoid artificial oscillation of the interface. Fluids in same cell are treated under effective fluid assumption to simplify the numerical computation. Sloshing in a rectangular tank by forced motion is first computed. Breaking and overturning waves are simulated. The slamming process is further studied Local pressure peak is found near the free surface. The impinging on liquid film of a single droplet is then investigated. The cavity depth, cavity diameter, and jet height are compared with experimental results. A bubble rising in an infinite column is also surveyed. The ratio of the friction force and surface tension plays an important role in determining the bubble shape and wake behind it. The wave generated by a surface ship is finally analyzed. Good agreement in wave making resistance between calculation and measurement is obtained. The numerical approach seems to be very promising in treating some two-phase flow problems.