週期性向上驅動之 垂直微滴管流場分析

A Study of the Vertical Flow Field of a Microtube with Upward Periodically Drive Pressure

鄭遠中(Yeuan-Jong Cheng)

指導教授 ： 許政行

中原大學/工學院/機械工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200409

摘要

本文主要研究不可壓縮之非牛頓流體，模擬液滴流自鉛直的微滴管中，受週期性壓力的驅動，朝上擠注的流場型態。利用不同的驅動條件、流體特性及接觸角(Contact Angle)的改變，模擬自由邊界下-軸對稱之液滴型態。假設流場為理想狀態下，初始為靜止狀態，施加週期性的壓力梯度加入流場內，使液滴動態行為產生變化。本文選用FLOW-3D內建計算流力模式；包括半隱性有限差分法(Semi-Implicit Finite-Difference)、配合體積分率法(Fractional Volume of Fluid, VOF)與自由網格法(Fractional Area/Volume Obstacle Representation, FAVOR)來模擬計算。為節省運算時間與加速趨近數值解上，採行了鬆弛法(Successive Over-Relaxation, SOR)來求解動量方程式之數值近似解。

關鍵字

微滴管 ； 週期性壓力 ； 接觸角

並列摘要

The main objective of this study is to simulate the dynamics of the flow of incompressible non-Newtonian fluids inject upward from a vertical capillary tube (i.e. micropipette) into ambient gas, under various conditions of fluids’ characteristics and related contact angles. The fluid is initially at rest, and a time-dependent pressure gradient is suddenly imposed on the fluid to start the flow.

The momentum equations are solved numerically by the commercial code; Flow-3D, which includes the Semi-Implicit Finite-Difference Method, Fractional Volume of Fluid Method and Fractional Area/Volume Obstacle Representation Method. In order to speed up the convergence of numerical iterations, the Successive Over-Relaxation Method; is used in the present study.

並列關鍵字

contact angle ； microtube ； time-dependent pressure gradient

參考文獻

1. 林逸啟 “滴管在不同壓力函數下之流場分析” 中原大學機械工程研究所碩士論文，(2001)。

2. E. A. Hauser, H. E. Edgerton, and W. B. Tucker, “The application of the high-speed motion picture camera to the research on the surface tension of liquid,” J. Phys Chem. 40, 973 (1936)

3. H. E. Edgerton, E. A. Hauser, and W. B. Tucker, “Studies in drop formation as revealed by the high-speed motion camera,” J. Phys Chem. 41, 1017 (1937)

4. D. H. Peregrine, G. Shoker, and A. Symon, “The bifurcation of liquid bridges,” J. Fluid Mech 212, 25 (1990)

5. X. D. Shi, M. P. Brenner, and S. R. Nagel,” A cascade of structure in a drop falling from a faucet, ” Science 265, 219 (1994)