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A STUDY ON THE NEARSHORE CURRENT USING NONLINEAR PARABOLIC MILD SLOPE AND QUASI-3D EQUATION

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Author(s)
안승현
Issued Date
2010
URI
http://dcoll.jejunu.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000004984
Abstract
The nearshore regions are very important places where are closely related with human civilization. In particular, Korea, the peninsula country, is close to the ocean so the nearshore regions have been used as distribution facilities such as harbors connecting rand and ocean transportation. Recently, due to the increase in the peoples' leisure time, the importance of nearshore regions adjacent to recreation areas and tourist attractions has been increasing. Thus, preservations and maintenances of nearshore regions have been issued.
In nearshore regions, the causes of sediment transport and shoreline erosion are waves, nearshore currents, the tide, wind, and the outflow of rivers. The most important cause among these has known as nearshore current.
When the water circulation system is changed by constructing artificial construction at the nearshore region, the balance in the sediment system will then be broken. Consequently, the shoreline and cross-profile may be damaged seriously. In fact, many problems such as erosion and accumulation by sediment transport occurred. Therefore, studies on the nearshore current are necessary to effectively use the nearshore area.
In this study, by using nonlinear parabolic mild slope and Quasi-3d equations, the circulation phenomena are simulated. When the numerical analysis is carried out, the numerical result of the wave model is calculated by the circulation model after input wave data are computed by the wave model. Through the above simultaneous process, the water circulation phenomena are analyzed, for the nearshore current is generated by wave-current interaction.
The numerical models used in this study are compared with observational result and numerical result of previous literature so proprieties of the numerical models are verified. The verification models are circulation phenomenon of the nearshore current in the coast established detached breakwater and inclined coast, and good agreements are obtained.
Circulation tendencies of the nearshore current using the numerical model in this study are computed. Study areas are Gangjeong Waters, Jeju and Haeundae Waters, Busan, respectively. The numerical analysises at Gangjeong, Jeju are performed to examine variations of the nearshore current caused by constructing artificial constructions, and those at Haeundae, Busan are performed to see effects of the wind stresses.
As a result, the understanding of the water circulation system within nearshore area is improved, and it is therefore considered that it can be applied to developing and utilizing the nearshore regions effectively.
Affiliation
제주대학교 대학원
Department
대학원 토목해양공학과
Advisor
김남형
Awarded Date
2010. 2
Table Of Contents
CHAPTER1: Introduction 1
1.1 Background 1
1.2 Objectives 2
1.3 Study Contents 3
CHAPTER2: Basic Equation for Wave Model 4
2.1 Mild Slope Equation 4
2.2 Parabolic Equation 6
2.3 Diffraction Model for Parabolic Equation 6
2.4 Nonlinear Combined Refraction and Diffraction Model 7
2.5 Wave-current Interaction Model 8
2.6 Wave Breaking Model 10
2.7 Radiation Stress 10
2.8 Wave-induced Mass Flux Model 12
CHAPTER3: Basic Equation for Circulation Model 13
3.1 Separation of Currents 13
3.2 Time-averaged and Depth-averaged Equations 13
3.3 Solution for Separation of Currents 18
3.4 Vertical Velocity Profiles 19
3.5 Solution for the Integral Terms 22
3.6 Final Form of the Momentum and Continuity Equations 24
3.7 Wind-induced Surface Shear Stress 25
CHAPTER4: Model Implements 26
4.1 Numerical Scheme 26
4.1.1 Crank-Nicolson Technique 26
4.1.2 Staggered Grid 27
4.2 Boundary Conditions 27
CHAPTER5: Verifications of the Numerical Model 29
5.1 Verification for Detached Break-water Case 29
5.2 Verification for Inclined Coast Case 31
CHAPTER6: Model Applications 33
6.1 Simulation for Effects of Artificial Reefs 33
6.1.1 Numerical Analysis Conditions 34
6.1.2 The Case without Artificial Reefs 34
6.1.3 The Case with Artificial Reefs at 20m Water Depth 37
6.1.4 The Case with Artificial Reef at 40m Water Depth 39
6.1.5 The Case with Artificial Reefs at 20m & 40m Water Depth 40
6.2 Simulation for Influence of Wind-induced Stress 41
6.2.1 Numerical Analysis Conditions 42
6.2.2 Results of Numerical Model 43
CHAPTER7: Conclusions and Remarks 46
7.1 Conclusions and Remarks 46
7.2 Future Works 47
Reference 48
Degree
Master
Publisher
제주대학교 대학원
Citation
안승현. (2010). A STUDY ON THE NEARSHORE CURRENT USING NONLINEAR PARABOLIC MILD SLOPE AND QUASI-3D EQUATION
Type
Dissertation
Appears in Collections:
General Graduate School > Civil and Ocean Engineering
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