DISTRIBUTION OF WAVE-INDUCED EXCESS MOMENTUM FLUXES OVER DEPTH AND APPLICATION TO THREE-DIMENSIONAL NUMERICAL MODELING OF WAVE-CURRENT INTERACTIONS

1.　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｓｔｕｄｙｏｆｗａｖｅｄｙｎａｍｉｃｓ,ＬｏｎｇｕｅｔＨｉｇｇｉｎｓａｎｄＳｔｅｗａｒｔｈａｖｅｐｒｅｓｅｎｔｅｄｔｈｅｗａｖｅｉｎｄｕｃｅｄｅｘｃｅｓｓｍｏｍｅｎｔｕｍｆｌｕｘｅｓｉｎｔｉｍｅａｖｅｒａｇｅｄａ?..     

NUMERICAL SIMULATION OF A MATHEMATICAL MODEL FOR WAVE PROPAGATION ON NON-UNIFORM CURRENT AND DEPTH

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｒｋｈｏｆｆ( 1 972 )ｄｅｒｉｖｅｄｔｈｅｗｅｌｌ ｋｎｏｗｎｃｏｍ ｂｉｎｅｄｒｅｆｒａｃｔｉｏｎ ｄｉｆｆｒａｃｔｉｏｎｅｑｕａｔｉｏｎｗｈｉｃｈｗａｓａｌｓｏｎａｍｅｄａｓｍｉｌｄ ｓｌｏｐｅｅｑｕａｔｉｏｎ .Ｔｈｅｅｑｕａｔｉｏｎｏｖｅｒ ｃｏｍｅｓｔｈｅｓｈｏｒｔｃｏｍｉｎｇｓｏｆｏｎｌｙｄｉｓｃｕｓｓｉｎｇｒｅｆｒａｃｔｉｏｎｐｈｅｎｏｍｅｎｏｎｆｏｒｔｈｅｒｅｆｒａｃｔｉｏｎｍｏｄｅｌａｎｄｏｎｌｙｓｔｕｄｙ ｉｎｇｄｉｆｆｒａｃｔｉｏｎｐｒｏｂｌｅｍｆｏ…     

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF THE FLOW FIELD AROUND A CIRCULAR CYLINDRICAL ARTIFICIAL ISLAND UNDER THE ACTION OF WAVES AND VISCOUS CURRENT

ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＡＮＤＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＹＯＦＴＨＥＦＬＯＷＦＩＥＬＤＡＲＯＵＮＤＡＣＩＲＣＵＬＡＲＣＹＬＩＮＤＲＩＣＡＬＡＲＴＩＦＩＣＩＡＬＩＳＬＡＮＤＵＮＤＥＲＴＨＥＡＣＴＩＯＮＯＦＷＡＶＥＳＡＮＤＶＩＳＣＯＵ...     

NUMERICAL SIMULATION OF FISH SWIMMING WITH RIGID PECTORAL FINS

The numerical simulation of the self-propelled motion of a fish with a pair of rigid pectoral fins is presented.A Navier-Stokes equation solver incorporating with the multi-block and overset grid method is developed to deal with the multi-body and moving body problems.The lift-based swimming mode is selected for the fin motion.In the lift-based swimming mode,the fin can generate great thrust and at the same time have no generation of lift force.It can be found when a pair of rigid pectoral fins generates the hydrodynamic moment,it may also generate a lateral force opposite to the centripetal direction,which has adverse effect on the turn motion of the fish.Furthermore,the periodic vortex structure generation and shedding,and their effects on the generation of hydrodynamic force are also demonstrated in this article.     

NUMERICAL SIMULATION FOR THE STEPPED SPILLWAY OVERFLOW WITH TURBULENCE MODEL

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｅｐｐｅｄｓｐｉｌｌｗａｙｈａｄｂｅｅｎｕｓｅｄａｔｔｈｅｂｅｇｉｎｎｉｎｇｏｆｔｗｅｎｔｙｃｅｎｔｕｒｙ[1 ] .Ｉｎ 1 971 ,Ｅｓｓｅｒｙｅｔａｌ.[2 ] ｃｏｎｄｕｃｔｅｄａｍｏｄｅｌｔｅｓｔｆｏｒｔｈｅｄｅｓｉｇｎｏｆ     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF INTAKE MODEL WITH CROSS FLOW

The hydrodynamics of a pump sump consisting of a main channel,pump sump,and intake pipe is examined using Truchas,a three-dimensional Navier-Stokes solver,with a Large Eddy Simulation(LES) turbulence model.The numerical results of streamwise velocity profiles and flow patterns are discussed and compared with experimental data of Ansar and Nakato.Fairly good agreement is obtained.Furthermore,unlike Ansar et al.'s inviscid solution,the proposed numerical model includes the effect of fluid viscosity and consid...     

NUMERICAL SIMULATION OF FLOW FOLD OF A RIVER WITH COMPLICATED BOUNDARIES

ＮＵＭＥＲＩＣＡＬ　ＳＩＭＵＬＡＴＩＯＮ　ＯＦ　ＦＬＯＷ　ＦＩＥＬＤ　ＯＦ　Ａ　ＲＩＶＥＲ　ＷＩＴＨ　ＣＯＭＰＬＩＣＡＴＥＤ　ＢＯＵＮＤＡＲＹＳＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＦＬＯＷＦＯＬＤＯＦＡＲＩＶＥＲＷＩＴＨＣＯＭＰＬＩＣＡＴＥＤＢ...     

NUMERICAL SIMULATION OF ROCK BREAKING MECHANISM WITH HIGH-PRESSURE WATER JET

Based on the analysis of experimental results.the rock damage model and the damage coupling model suitable for the whole rock breaking process with water jet were established with continuous damage mechanics and micro damage mechanics, and the numerical method was developed with continuum mechanics and the FEM theory. The rock breaking mechanism with water jet was studied systematically with numerical simulation for the first time in the field of water-jet rock breaking. The numerical results agree with the experimental ones which shows that the presented method is reasonable and can reflect the reality of water-jet rock breaking. The conclusion can be applied in practice.     

THE EFFECTS OF RADIATION STRESS ON WAVE HEIGHTS AND SEA LEVEL IN THE INTERACTION OF COUPLED WAVE-TIDE-SURGE IN THE COASTAL AREA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｎｄｇｅｎｅｒａｔｅｓｂｏｔｈｗａｖｅｓａｎｄｓｔｏｒｍｓｕｒｇｅｓ,ｓｏｔｈｅｉｒ ｇｅｎｅｒａｔｉｏｎｉｓｃｌｏｓｅｌｙｒｅｌａｔｅｄ .Ｆｕｒｔｈｅｒ ｍｏｒｅ ,ｓｔｒｏｎｇｌｙｎｏｎｌｉｎｅａｒｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｅｎｔｉｄｅｓａｎｄｓｔｏｒｍｓｕｒｇｅｓｅｘｉｓｔｉｎｓｈａｌｌｏｗｗａｔｅｒ .Ｔｈｅｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｅｎｗａｖｅａｎｄｔｉｄｅ ｓｕｒｇｅｍｏｔｉｏｎ ,ｂｅｔｗｅｅｎｗａｖｅａｎｄｔｈｅｍｅａｎｆｌｏｗｏｒｗａｔｅ…     

NUMERICAL SIMULATION OF STRESS-INDUCED SECONDARY FLOWS WITH HYBRID FINITE ANALYTIC METHOD

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｕｒｂｕｌｅｎｔｓｔｒｕｃｔｕｒｅｓｉｎｎｏｎ ｃｉｒｃｕｌａｒｄｕｃｔｓａｎｄｏｐｅｎｃｈａｎｎｅｌｓａｒｅｃｈａｒａｃｔｅｒｉｚｅｄｂｙｌｏｎｇｉｔｕｄｉ ｎａｌｖｏｒｔｉｃｅｓ .Ｔｈｅｓｅｖｏｒｔｉｃｅｓａｒｅｔｈ     

CALCULATION OF VISCOUS FLOW AROUND CIRCULAR CYLINDER WITH THREE-DIMENSIONAL NUMERICAL SIMULATION

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｏｗａｒｏｕｎｄａｃｉｒｃｕｌａｒｃｙｌｉｎｄｅｒｉｓｖａｌｕａｂｌｅｉｎｏｉｌｃｏｍｐａｎｉｅｓｏｒｏｆｆｓｈｏｒｅｉｎｄｕｓｔｒｙｔｈａｔｒｅｌｙｉｎｍｏｓｔｃａｓｅｓｏｎｓｕｂｓｅａｐｉｐｅｌｉｎｅｏｒｒｉｓｅｒｓｔｏｔｒａｎｓｐｏｒｔｇａｓａｎｄｏｉｌｆｒｏｍｏｃｅａｎｇｒｏｕｎｄｓｔｏｌａｎｄｏｒｓｕｒｆａｃｅｐｌａｔｆｏｒｍ .Ｗｅｓｈｏｕｌｄｅｎｓｕｒｅｔｈａｔｔｈｅｓｅｏｆｆｓｈｏｒｅｓｔｒｕｃｔｕｒｅｓａｒｅｒｅｓｉｓ ｔａｎｔａｎｄｓｔａｂ…     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF THERMAL-HYDRAULIC PERFORMANCE OF A CIRCULAR TUBE WITH EDGEFOLD-TWISTED-TAPE INSERTS

Three-dimensional numerical simulations and experiments were carried out to study the heat transfer characteristics and the pressure drop of air flow in a circular tube with Edgefold-Twisted Tape (ETT) inserts and with classic Spiral-Twisted-Tape (STT) inserts of the same twist ratio. The RNG turbulence model for mildly swirling flows, the enhanced wall treatment for low Reynolds numbers, and the SIMPLE pressure-velocity method were adopted to simulate the flow and heat transfer characteristics. Within the range of Reynolds number from 2 500 to 9 500 and the twist ratio y from 5.4 to 11.4, the Nusselt number of the tube with ETT inserts is found to be 3.9% ? 9.2% higher than that with STT inserts, and the friction factor of the tube with ETT inserts is 8.7% ? 74% higher than that of STT inserts. The heat enhancement is due to higher tangential velocity and asymmetrical velocity profile with the increase and decrease of the periodic velocity within an edgefold length. It is found that main factors affecting the heat transfer of ETT inserts are the twist angle and the gap width between the tube and inserts. A larger twist angle leads to a higher tangential velocity, and larger Nusselt number and friction factor. The thermal-hydraulic performance slowly decreases as the twist angle increases. The gap width between tube and inserts has a significant influence on the heat transfer, while little influence on pressure drops. The thermal-hydraulic performance increases in average by 124% and 140% when the gap width reduces from 1.5 mm to 1.0 mm and 0.5 mm. The larger the gap width, the higher velocity through the gap will be, which would reduce the main flow velocity and tangential velocity. So a small gap is desirable. Comparing experimental and numerical results at variable air flow and tube wall temperature, the numerical results are found to be in a reasonable agreement with the experiment results, with difference of the Nusselt number in a range of 1.6% ? 3.6%, and that of the friction factor in a range of 8.2% ? 13.6%.     

NUMERICAL SIMULATION OF TRANSIENT CUTTINGS TRANSPORT WITH FOAM FLUID IN HORIZONTAL WELLBORE

With considering the interlayer mass transfer and fluid influx from the reservoir, a one-dimensional two-layer hydraulic model was established to describe the mechanism of transient cuttings transport with foam fluid in horizontal well section. The model was numerically calculated based on the modified SIMPLE algorithm, and the height of cuttings bed was predicted by the trial-and-error method. Sensitivity analysis was conducted on the affecting factors on the cuttings transport performance. Results show that cuttings deposition moves along the horizontal wellbore from the drilling bit, and finally achieves a steady state with dynamic balance. Dimensionless cuttings bed height decreases with the increase of foam quality or foam flow rate, but increases with the increase of drillpipe eccentricity, cuttings size or drilling rate. The influx of water and gas from the reservoir is helpful to improve the cuttings transport efficiency with foam. The proposed model offers theoretical guidelines for hydraulic parameter design and hole cleaning control in foamed horizontal drilling.     

NUMERICAL SIMULATION OF BUBBLE FLOW INTERACTIONS

Bubble flow interaction can be important in many practical engineering applications. For instance, cavitation is a problem of interaction between nuclei and local pressure field variations including turbulent oscillations and large scale pressure variations. Various types of behaviours fundamentally depend on the relative sizes of the nuclei and the length scales of the pressure variations as well as the relative importance of bubble natural periods of oscillation and the characteristic time of the field pressure variations. Similarly, bubbles can significantly affect the performance of lifting devices or propulsors. We present here some fundamental numerical studies of bubble dynamics and deformation, then a practical method using a multi-bubble Surface Averaged Pressure (DF-Multi-SAP©) to simulate cavitation inception and scaling, and connect this with more precise 3-D simulations. This same method is then extended to the study of two-way coupling between a viscous compressible flow and a bubble population in the flow field.     

OPTIMIZING LAYOUT OF URBAN STREET CANYON USING NUMERICAL SIMULATION COUPLING WITH MATHEMATICAL OPTIMIZATION

1. INTRODUCTION Vehicular emissions have become one of thmain sources of urban atmospheric pollution in Chinwith the development of the urban construction andthe increase in the number of vehicles. There are lots of factors influencing the transport and dispersion of vehicular exhausted pollutants and further influencing the local air quality, among which the gas dynamical effect due to the mechanical turbulence from huge buildings and street canyons is especially remarkable. Previous stu…     

NUMERICAL SIMULATION OF STREAMBED HEAT TRANSFER

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｉｍｕｌａｔｉｏｎｏｆｓｔｒｅａｍｗａｔｅｒｔｅｍｐｅｒａｔｕｒｅｉｓｓｉｇｎｉｆｉｃａｎｔｌｙｉｍｐｏｒｔａｎｔｆｏｒｔｈｅｓｔｕｄｙｏｆｎｕｍｅｒｉｃａｌｍｏｄｅｌｉｎｇｏｆｒｉｖｅｒｉｃｅｐｒｏｃｅｓｓｅｓ［１］　．Ｈｉｓｔｏｒｉｃａｌｌｙ，ｔｈｅｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｉｎｇｏｆｔｈｅｔｒａｎｓｐｏｒｔａｎｄｆａｔｅｏｆｈｅａｔｉｎａｗａｔｅｒｂｏｄｙｈａｓｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｅｘｔｅｎｓｉｖｅｓｔｕｄｙｆｏｒｖａｒｉｏｕｓｒｅ…     

NUMERICAL SIMULATION OF SLOSHING IN RECTANGULAR TANK WITH VOF BASED ON UNSTRUCTURED GRIDS

A new method for sloshing simulation in a sway tank is present, in which the two phase interface is treated as a physical discontinuity, which can be captured by a well-designed high order scheme. Based on Normalized Variable Diagram (NVD), a high order discretization scheme with unstructured grids is realized, together with a numerical method for free surface flow with a fixed grid. This method is implemented in an in-house code General Transport Equation Analyzer (GTEA) which is an unstructured grids finite volume solver. The present method is first validated by available analytical solutions. A simulation for a 2-D rectangular tank at different excitation frequencies of the sway is carried out. A comparison with experimental data in literature and results obtained by commercial software CFX shows that the sloshing load on the monitor points agrees well with the experimental data, with the same grids, and the present method gives better results on the secondary peak. It is shown that the present method can simulate the free surface overturning and breakup phenomena.     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF TIDES AND CURRENTS IN FUSHAN BAY, QINGDAO

The three-dimensional Princeton Ocean Model (POM) was employed to simulate the tide and current simultanuously for the first time in the Fushan Bay, Qingdao, China By adopting the elevation condition that was combined with the tides M2, $2, K1 and O1 at the open boundary and by choosing the proper value of bottom roughness, the horizontal and vertical distributions of the tidal current and water level variations in the bay were computed. The results agree well with the field observation data, indicating that this model can be used to predict accurately the variation of tides and currents in the Fushan Bay and other costal regions in the future.Our study also provides useful information and a data base for the Olympic Projects that will be conducted in the Fushan Bay in 2008.     

NUMERICAL SIMULATION OF TURBULENT FLOW CHARACTERISTICS IN A CURVED PIPE WITH A BAFFLE

A numerical study on the characteristics of developing turbulent flow in a curved pipe with a baffle was carried out in body-fitted coordinates with the k-ε model turbulence. A curved duct of square cross-section was examined first, and the results agree very well with the experimental data. Then two kinds of pipes, a normal curved pipe and that with a baffle were studied. The computational results are presented and compared with each other to illustrate the changes of the flow after adding the baffle. The longitudinal velocity in the pipe with a baffle was characterized by outer velocity bigger than the inner one. The secondary flow was characterized by four-vortex structure with the intensity reduced, which results in the equability of the flow field of the cross-section compared with that without a baffle, and has much more significant meaning in engineering.     

NUMERICAL SIMULATION ON EMERGENCY TUNNEL FIRES WITH TRANSVERSE VENTILATION

ＮＯＭＥＮＣＬＡＴＵＲＥＣｓ：ＳｍａｇｏｒｉｎｓｋｙｃｏｎｓｔａｎｔＣｖ,Ｃｐ：Ｓｐｅｃｉｆｉｃｈｅａｔａｔｃｏｎｓｔａｎｔｖｏｌｕｍｅａｎｄｐｒｅｓｓｕｒｅ,ｒｅｓｐｅｃｔｉｖｅｌｙ,（Ｊ／ｋｇＫ）ｇ：Ｇｒａｖｉｔｙａｃｃｅｌｅｒａｔｉｏｎｖｅｃｔｏｒ,（ｍ／ｓ２）ｈｗ：Ｏｖｅｒａｌｌｃｏｅｆｆｉｃｉｅｎｔｏｆｈｅａｔｔｒａｎｓｆｅｒｏｆｔｕｎｎｅｌｗａｌｌ,（Ｗ／ｍ２Ｋ）Ｐ：Ｐｒｅｓｓｕｒｅ,（Ｐａ）Ｐ０：Ａｔｍｏｓｐｈｅｒｉｃａｂｖｏｌｕｔｅｐｒｅｓｓｕｒｅ,（Ｐａ）ｐ：Ｍｏｔｉｖｅｐｒｅ…