MASS CONSERVATION BEHAVIOR OF WAVE EQUATION MODEL FOR SOLVING SHALLOW WATER EQUATIONS

ＭＡＳＳＣＯＮＳＥＲＶＡＴＩＯＮＢＥＨＡＶＩＯＲＯＦＷＡＶＥＥＱＵＡＴＩＯＮＭＯＤＥＬＦＯＲＳＯＬＶＩＮＧＳＨＡＬＬＯＷＷＡＴＥＲＥＱＵＡＴＩＯＮＳＷｕＪｉａｎ－ｋａｎｇ（ＨｕａｚｈｏｎｇＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇ...     

WAVE EQUATION MODEL FOR SHIP WAVES IN BOUNDED SHALLOW WATER

1.　 INTRODUCTIONIn the recentyears,waves in coastal shallow water,generated by marine traffic and in-tensified by port expansion,interaction with structures and reflection of land boundaries,has become a crucial factor affecting waterenvironmentsand engineering operation.In com-parison with the wind waves and ocean swells,waves inside harbor exhibitanomalous waveheight in certain areas.The dominantship waves are hardly dissipated in the harbor due tothe interaction with shorelines,and may…     

A NEW FINITE VOLUME METHOD FOR SOLVING SHALLOW WATER EQUATIONS

This paper presents a new numerical model using the finite volume method witharbitrary polygonal elements,It is suitable for simulating the shallow water problem with com-plex topography and boundary conditions.The calculated results show that this kind of methodhas the advantages of good stability,convenience of solving,easy programming,less,computingtime and storage,high accuracy,ect.     

WAVE EQUATION MODEL FOR NUMERICAL SOLUTIONS OF ADVECTION－DOMINANT HEAT TRANSFER

ＷＡＶＥ　ＥＱＵＡＴＩＯＮ　ＭＯＤＥＬ　ＦＯＲ　ＮＵＭＥＲＩＣＡＬ　ＳＯＬＵＴＩＯＮＳ　ＯＦ　ＡＤＶＥＣＴＩＯＮ－ＤＯＭＩＮＡＮＴ　ＨＥＡＴ　ＴＲＡＮＳＦＥＲＷＡＶＥＥＱＵＡＴＩＯＮＭＯＤＥＬＦＯＲＮＵＭＥＲＩＣＡＬＳＯＬＵＴＩＯＮＳＯＦＡＤＶＥＣＴ...     

NUMERICAL STUDY OF SQUARE-STERN SHIP WAVE IN SHALLOW WATER

This paper employed shallow water equations with moving pressure to calculate water waves generated by a square-stern ship in shallow water. The moving ship is considered as moving pressure on free surface. The finite element method with moving grids is used to solve the shallow water equations based on wave equation model [3]. A non-reflection boundary condition [5]is imposed on open boundaries surrounding the ship. 3-D surface elevations, depth-averaged horizontal velocities are presented. The numerical solutions are physically reasonable. It is found that wave resistance coefficients, draftchange and pitch angle vary rapidly in neighborhood of critical flow (Fh=u/ gh= 0. 9 -1. 1). The numerical results also indicate that the wave resistance coefficients, draft change and pitch angle of square-stern ship are larger than those of sharp-stern ship with the same hull structure at the same speed.     

A HIGH RESOLUTION FINITE VOLUME METHOD FOR SOLVING SHALLOW WATER EQUATIONS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｎｅｃｅｓｓａｒｙｔｏｃｏｎｄｕｃｔｆｌｕｉｄｆｌｏｗａｎａｌｙｓｅｓｉｎｍａｎｙａｒｅａｓ ,ｓｕｃｈａｓｉｎｅｎｖｉｒｏｎｍｅｎｔａｌａｎｄｈｙｄｒａｕｌｉｃｅｎｇｉｎｅｅｒｉｎｇ .Ｎｕｍｅｒｉｃａｌｍｅｔｈｏｄｂｅｃｏｍｅｓｇｒａｄｕａｌｌｙｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔａｐ ｐｒｏａｃｈ .Ｔｈｅｃｏｍｐｕｔａｔｉｏｎｆｏｒｇｅｎｅｒａｌｓｈａｌｌｏｗｗａｔｅｒｆｌｏｗ ｐｒｏｂｌｅｍｓａｒｅｓｕｃｃｅｓｓｆｕｌ,ｂｕｔｔｈｅｓｔｕｄｉｅｓｏｆｃｏｍｐｌｅ…     

IMPROVED MODEL FOR THREE DIMENSIONAL NONLINEAR WATER WAVE FORCE PREDICTION

An improved model for numerically predicting nonlinear wave forces exerted on an offshore structure is pro-posed.In a previous work[9],the authors presented a model for the same purpose with an open boundary condi-tion imposed,where the wave celerity has been defined constant.Generally,the value of wave celerity is time-de-pendent and varying with spatial location.With the present model the wave celerity is evaluated by an upwind dif-ference scheme,which enables the method to be extended to conditions of variable finite water depth,where thevalue of wave celerity varies with time as the wave approaches the offshore structure.The finite difference methodincorporated with the time-stepping technique in time domain developed here makes the numerical evolution effec-tive and stable.Computational examples on interactions between a surface-piercing vertical cylinder and a solitarywave or a cnoidal wave train demonstrates the validity of this program.     

AN INTEGRAL EQUATION DESCRIBING RIDING WAVES IN SHALLOW WATER OF FINITE DEPTH

1 .　INTRODUCTIONSmall scalewavessuperposedonlarge scalewavesarecalled“ridingwaves” .Small scalewavesonoceansurfacehasaroused greatinterestwiththegreatimprovementofprecisionofmeasuringinstrumentsusedinthefieldofremotesensing .Thisstudyaimsatunderstandingthemotionofthelarge scalewavesandtheenergyexchangebetweenairandseathroughsomeinformationofsmall scalewaves .Henyeyetal .[2 ] derivedthemotione quationtothefirstorderofridingwavesbyusingacanonicalHamiltonianformulationandassumingsmallwave…     

TWO-PROCEDURE OF MODEL RELIABILITY-BASED OPTIMIZATION FOR WATER DISTRIBUTION SYSTEMS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｌｉａｂｉｌｉｔｙｏｆｗａｔｅｒｄｉｓｔｒｉｂｕｔｉｏｎｓｙｓｔｅｍｓｉｓｏｆｉｎｃｒｅａｓｉｎｇｃｏｎｃｅｒｎｔｏｗａｔｅｒｄｉｓｔｒｉｂｕｔｉｏｎｓｙｓｔｅｍｄｅｓｉｇｎｅｒｓａｎｄｏｐｅｒａｔｏｒｓ.Ｔｈｅａｐｐｌｉｃａｔｉｏｎｏｆｒｅｌｉａｂｉｌｉｔｙｃｏｎｃｅｐｔｓｔｏｔｈｅｏｐｔｉｍｉｚａｔｉｏｎｍｏｄｅｌｓｆｏｒｔｈｅｍｉｎｉｍｕｍ ｃｏｓｔｄｅｓｉｇｎｏｆｗａｔｅｒｄｉｓｔｒｉｂｕｔｉｏｎｓｙｓｔｅｍｓｃａｎｅｎｓｕｒｅａｒｅａｓｏｎａｂｌｅｔｒａ…     

A NEW IMPLICIT SCHEME FOR SOLVING 3-D SHALLOW WATER FLOWS

Based on the improved ADI method, this article proposes an improved implicit finite difference scheme for solving 3-D shallow water flows. The main objective is to design a numerical relation between the horizontal velocity on each layer and the depth-averaged velocity for employing the improved ADI method. With the free surface elevation and the depth-averaged velocity obtained by using essentially 2-D depth-averaged mode, the velocity profiles can be obtained easily and simultaneously. The wind-induced flows, the open channel flows due to the pressure gradient and the tidal flows in coastal waters are simulated, and the results are consistent well with the analytical solution and the field data, which shows that the present implicit scheme is stable and effective, and the established model is practical. Moreover, when only one vertical layer is specified, the present 3-D numerical model is reducea to the 2-D depth-averaged model.     

NUMERICAL MODELING OF WAVE EVOLUTION AND RUNUP IN SHALLOW WATER

Based on the Navier-Stokes (N-S) equations for viscous, incompressible fluid and the VOF method, 2-D and 3-D Numerical Wave Tanks (NWT) for nonlinear shallow water waves are built. The dynamic mesh technique is applied, which can save computational resources dramatically for the simulation of solitary wave propagating at a constant depth. Higher order approximation for cnoidal wave is employed to generate high quality waves. Shoaling and breaking of solitary waves over different slopes are simulated and analyzed systematically. Wave runup on structures is also investigated. The results agree very well with experimental data or analytical solutions.     

A NUMERICAL MODEL OF FLOW FIELD AND WATER QUALITY FOR TIDAL REGIONS BASED ON TRIANGULAR MESHES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＵｐｔｏｎｏｗ ,ｔｈｅｒｅｐｏｒｔｓｆｏｒｓｏｌｖｉｎｇ 2Ｄｄｅｐｔｈ ｉｎｔｅｇｒａｔｅｄｅｑｕａｔｉｏｎｓｏｆｆｌｏｗａｎｄｍａｓｓｔｒａｎｓｐｏｒｔｉｎｔｉｄａｌｒｅｇｉｏｎｈａｖｅｂｅｅｎｉｎｔｒｏｄｕｃｅｄｉｎｌａｒｇｅｎｕｍ ｂｅｒｓ .ＦｒｏｍｔｈｅｂｅｇｉｎｎｉｎｇｏｆＹａｎｅｎｋｏ[1] .ＴｈｅＦｉ ｎｉｔｅＤｉｆｆｅｒｅｎｃｅＭｅｔｈｏｄ (ＦＤＭ )ｈａｓｂｅｅｎｗｉｄｅｌｙａｐｐｌｉｅｄｂｙＦａｌｃｏｎｅｒ[2 ] ,ＶｉｎｃｅｎｚＣａｓｕｌｌｉ[3,5] ,ＨｅＳｈ…     

AN UNSTRUCTURED FINITE-VOLUME ALGORITHM FOR NONLINEAR TWO-DIMENSIOAL SHALLOW WATER EQUATION

An unstructured finite-volume numerical algorithm was presented for solution of the two-dimensional shallow water equations, based on triangular or arbitrary quadrilateral meshes. The Roe type approximate Riemann solver was used to the system. A second-order TVD scheme with the van Leer limiter was used in the space discretization and a two-step Runge-Kutta approach was used in the time discretization. An upwind, as opposed to a pointwise, treatment of the slope source terms was adopted and the semi-implicit treatment was used for the friction source terms. Verification for two-dimension dam-break problems are carried out by comparing the present results with others and very good agreement is shown.