本文探討分層異重流的實驗。為兩種有密度差異的分層流體流動進另一個密度比分層流體相對較小的背景流體中的實驗。主要目的在於透過理論解析以及實驗系統性的探討分層異重流於慣性區段的影響。於定量與定性分析過程中，了解分層異重流在運動中所產生的混合及分離的過程。於慣性區段的異重流運動型態將遵守3/2 指數關係，並且與密度比(rho∗) 以及重力比(B∗) 相關。透過觀察分層異重流於慣性區段之福祿數 (FI) 變化、rho∗與B∗之關聯性來了解流動型態的特性。首先從實驗之分析結果得知，當密度均勻之均質異重流體進入背景流體其慣性區段的FI值約為1.33，其值皆大於非均質之分層異重流的例子。當初始分層條件為弱分層情形時(0.5<rho∗<1)，其分層異重流產生混合的現象也相當迅速；若初始分層條件為強分層情形時 (0<rho∗<0.5)，其混合的現象則相對緩慢。於弱分層與強
分層的情形之間，當重力比值較大時(B∗→1)會發生以上層流體為主導的形流動型態；若是重力比值較小時 (B∗→0) 會發生以下層流體為主導的形流動型態。藉由慣性區段的FI值、rho∗以及重力比B∗於幫助了解分層異重流的運動型態和特徵。

This paper examines experiment of density-stratified gravity currents. There are two kinds of fluid of density-stratified difference penetrating into ambient fluid. The main objective focus on investigating the influence of density-stratification on the gravity currents is systematically explored in the inertial phase through the theoretical and experimental studies. The mixing and discrete processes are represented produced by density-stratified buoyancy source in qualitative and quantitative method. In the inertial phase of propagation, the flow pattern of gravity current follows the 3/2 power relationship related with the Froude number, density difference ratio (rho∗) and distribution of buoyancy (B∗). First, from the experimental results, the Froude number in the inertial phase has its maximum value at 1.33 as the density and buoyancy is homogeneous, always great than the values of non-homogeneous stratified fluid. When density-stratified gravity currents from a weakly stratified source (0.5<rho∗<1), the mixing between the two-layer fluids is quick; from the strongly stratified source (0<rho∗<0.5), the mixing between the two-layer fluid is generally slower. Between weakly and strongly stratified sources, the flow is controlled by the upper layer fluid when the distribution of buoyancy large (B∗→1) ; when the distribution of buoyancy few the flow is controlled by the lower layer fluid (B∗→0) . Since the Froude number, density difference ratio and distribution of buoyancy is helpful in offering possible explanations for observed features from density-stratified gravity currents.

目錄
摘要	I
Abstract	II
目錄	IV
表目錄	V
圖目錄	VI
第一章　緒論	1
1.1 前言	1
1.2 研究動機與目的	3
第二章　文獻回顧	4
第三章　研究方法	6
3.1實驗理論	6
3.2實驗裝置與方式	10
3.3實驗步驟與流程	14
第四章 實驗結果與分析	15
4.1均質異重流	18
4.1.1　定性特徵	18
4.1.2　定量結果	19
4.2　弱分層之分層異重流	21
4.2.1　定性特徵	21
4.2.2　定量結果	25
4.3　強分層之分層異重流	28
4.3.1　定性特徵	28
4.3.2　定量結果	33
第五章 結論	37
參考文獻	42
表目錄
表1　實驗初始條件設計表	12
表2　實驗結果資料表	16


圖目錄
圖1.1　定界交換流實驗影像圖	2
圖1.2　分層異重流實驗影像圖	2
圖3.1　實驗水槽內壁之側視示意圖	10
圖3.2　分層流體製做之示意圖	12
圖4.1　剪應力不穩定現象圖	18
圖4.2　實驗編號A1影像圖	19
圖4.3　實驗編號A1結果圖	20
圖4.4　實驗編號B1影像圖	22
圖4.5　實驗編號E3影像圖	23
圖4.6　實驗編號D5影像圖	24
圖4.7　實驗編號B1結果圖	25
圖4.8　實驗編號E3結果圖	26
圖4.9　實驗編號D5結果圖	27
圖4.10　實驗編號B9影像圖	29
圖4.11　實驗編號D4影像圖	30
圖4.12　實驗編號C8影像圖	31
圖4.13　實驗編號B9結果圖	33
圖4.14　實驗編號D4結果圖	34
圖4.15　實驗編號C8結果圖	35
圖5.1　 FI 值與 B* 值關係圖	38
圖5.2　 ρ*與 B*關係分佈圖	40

參考文獻
1. Adduce, C., Sciortino, G. & Proietti, S. 2012 Gravity currents produced by lock-exchanges:experiments and simulations with a two layer shallow-water
model with entrainment. J.Hydraul. Eng. 138 (2), 111–121.
2. Allen, J. 1985 Principles of Physical Sedimentology. Allen & Unwin.
3. Barr, D. I. H. 1967 Densimetric exchange flows in rectangular channels. La
Houille Blanche 22, 619–631.
4. Benjamin, T. B. 1968 Gravity currents and related phenomena. J. Fluid Mech. 31,
209–248.
5. Cantero, M., Lee, J., Balachandar, S. & Garcia, M. 2007 On the front velocity of
gravity currents. J. Fluid Mech. 586, 1–39.
6. Caulfield, C. P. & Kerswell, R. R. 2001Maximal mixing rate in turbulent stratified
Couette flow. Phys. Fluids 13, 894–900.
7. Choux, C. M. & Druitt, T. H. 2002 Analogue study of particle segregation in
pyroclastic density currents, with implications for the emplacement mechanisms
of large ignimbrites. Sedimentology 49, 907–928.
8. Clayton, C. J. 1994 Contrasting sediment gravity flow processes in the late
Llandovery, Rhud-dnant Grits turbidite system, Welsh Basin. J. Geol. 29,
167–181.
9. Dai, A. 2013 Experiments on gravity currents propagating on different bottom
slopes. J. Fluid Mech. 731, 117–141.
10. Dai, A. 2014 Non-Boussinesq gravity currents propagating on different bottom slopes. J. Fluid Mech. 741, 658–680.
11. Dai, A. 2015 High-resolution simulations of downslope gravity currents in the acceleration phase.Phys. Fluids 27, 076602.
12. Fannelop, T. K. 1994 Fluid Mechanics for Industrial Safety and Environmental Protection.Elsevier.
13. Gladstone, C., Ritchie, L. J., Sparks, R. S. J. & Woods, A. W. 2004 An experimental investigation of density-stratified inertial gravity currents. Sedimentology 51, 767–789.
14. Gladstone, C. & Sparks, R. S. J. 2002 The significance of grainsize breaks in turbidites and pyroclastic density current deposits. J. Sed. Res. 72, 182–196.
15. Hopfinger, E. J. 1983 Snow avalanche motion and related phenomena. Annu. Rev. Fluid Mech. 15, 47-76.
16. Huppert, H. 1982 The propagation of two-dimensional and axisymmetric viscous gravity currents over a rigid horizontal boundary surface. J. Fluid Mech. 121, 43–58.
17. Huppert, H. & Simpson, J. 1980 The slumping of gravity currents. J. Fluid Mech. 99, 785–799.
18. Jones, C. S., Cenedese, C., Chassignet, E. P., Linden, P. F. & Sutherland, B. R.
2014 Gravity current propagation up a valley. J. Fluid Mech. 762, 417–434.
19. Keulegan, G. H. 1958 The motion of saline fronts in still water. Natl Bur. Stand.
Rep. 5813.
20. La Rocca, M., Adduce, C., Lombardi, V., Sciortino, G. & Hinkermann, R. 2012a
Developement of a lattice boltzmann method for two-layered shallow-water flow.
Int. J. Numer. Methods Fluids 70 (8), 1048–1072.
21. La Rocca, M., Adduce, C., Sciortino, G., Bateman, P. A. & Boniforti, M. A.
2012b A two-layer shallow water model for 3D gravity currents. J. Hydraul. Res.
50 (2), 208–217.
22. La Rocca, M., Adduce, C., Sciortino, G. & Pinzon, A. B. 2008 Experimental and
numerical simulation of three-dimensional gravity currents on smooth and rough bottom. Phys. Fluids 20 (10), 106603
23. Lombardi, V., Adduce, C., Sciortino, G. & La Rocca, M. 2015 Gravity currents flowing upslope: laboratory experiments and shallow-water simulations. Phys. Fluids 27, 016602.
24. Marino, B., Thomas, L. & Linden, P. 2005 The front condition for gravity currents. J. Fluid Mech. 536, 49–78.
25. Marleau, L. J., Flynn, M. R. & Sutherland, B. R. 2014 Gravity currents propagating up a slope. Phys. Fluids 26, 046605.
26. Maxworthy, T. 2010 Experiments on gravity currents propagating down slopes. Part 2. The evolution of a fixed volume of fluid released from closed locks into a
long, open channel. J. Fluid Mech. 647, 27–51.
27. Maxworthy, T. & Nokes, R. I. 2007 Experiments on gravity currents propagating down slopes. Part 1. The release of a fixed volume of heavy fluid from an
enclosed lock into an open channel. J. Fluid Mech. 584, 433–453.
28. McCave, I. N. & Jones, K. P. N. 1988 Deposition of ungraded muds from high density non-turbulent turbidity currents. Nautre 333, 250–252.
29. Parsons, J. D. & Garcia, M. H. 1988 Similarity of gravity current fronts. Phys. Fluids 10, 3209–3213.
30. Rottman, J. W. & Simpson, J. E. 1983 Gravity currents produced by instantaneous releases of a heavy fluid in a rectangular channel. J. Fluid Mech. 135, 95–110.
31. Shin, J., Dalziel, S. & Linden, P. 2004 Gravity currents produced by lock exchange. J. Fluid Mech.
 521, 1–34.
32. Simpson, J. 1997 Gravity Currents, 2nd edn. Cambridge University Press. Sinclair, H. D. 1994 The influence of lateral basinal slopes on turbidite sedimentation in
the Annot Sandstones of SE France. J. Sed. Res. 64, 42–54.
33. Turner, J. S. 1979 Buoyancy Effects in Fluids. Cambridge University Press.
34. Ungarish, M., Mériaux, C. A. & Kurz-Besson, C. B. 2014 The propagation of gravity currents in a V-shaped triangular cross-section channel: experiments and theory. J. Fluid Mech. 754, 232–249.