An Implicit Coupled 1D/2D Model for Unsteady Subcritical Flow in Channel Networks and Embayment

In this study, 1D and 2D shallow-water models were coupled to simulate unsteady flow in channel networks and embayment. The 1D model solved the 1D shallow-water equations (St. Venant) using the Preissmann box method and targeted long narrow reaches of the river networks, while the 2D model targeted broad channels and embayment and solved the 2D shallow-water equations using a semi-implicit scheme applied to an unstructured grid of triangular cells. The 1D and 2D models were solved simultaneously by building a matrix for the free surface elevation at every 1D junction and 2D cell center. Velocities were then computed explicitly based on the results at the previous time step and the updated water level. The originality of the scheme arose from a novel coupling method. The results showed that the coupled 1D/2D model produced identical results as the full 2D model in classical to benchmark problems with considerable savings in computational effort. Application of the model to the Pearl River Estuary in southern China showed that complex patterns of tidal wave propagation could be efficiently modeled.

Simulation of the Hydrodynamic Functioning of the Cavally River Using a Coupled 1D-2D Model in the Ity Area (Zouan-Hounien in Côte d’Ivoire)

In recent years, the Cavally River has been subject to multiple activities, including the construction of diversion channels and a bridge that makes it vulnerable to flooding. In order to assess the impact of these hydraulic structures on the river hydrodynamic functioning, a 1D-2D model was realized. The implementation of the 1D-2D model consisted of first running the 1D model, then the 2D model, and finally in coupling them. The 1D-2D model was designed with the 1988 flood hydrograph, a Manning’s coefficient of 0.052 m1/3/s for the minor bed and 0.06 m1/3/s for the major bed. The results of the hydraulic model show that the velocities are almost identical to those of the Cavally in natural operation. The values of the velocities are included between 0.4 m/s and 1.3 m/s at the level of the minor bed of the river and between 0.06 m/s and 0.71 m/s at the level of the floodplains. The average water level for flood propagation is 262.37 ± 0.44 m before construction of the structures and 262.23 ± 0.85 m after construction of the structures. The 0.41 m reduction in water level due to the diversion canal and bridge is negligible compared to the total fluctuations of the Cavally River, which vary from 6 to 7 m over the year.

Hydrodynamic Response of A Fully Coupled TLP Hull-TTR System with Detailed Modeling of A Hydraulic Pneumatic Tensioner and Riser Joints

Tension Leg Platform(TLP)in deepwater oil and gas field development usually consists of a hull,tendons,and top tension risers(TTRs).To maintain its top tension,each TTR is connected with a tensioner system to the hull.Owing to the complicated configuration of the tensioners,the hull and TTRs form a strong coupled system.Traditionally,some simplified tensioner models are applied to analyze the TLP structures.There is a large discrepancy between their analysis results and the actual mechanism behaviors of a tensioner.It is very necessary to develop a more detailed tensioner model to consider the coupling effects between TLP and TTRs.In the present study,a fully coupled TLP hull-TTR system for hydrodynamic numerical simulation is established.A specific hydraulic pneumatic tensioner is modeled by considering 4 cylinders.The production TTR model is stacked up by specific riser joints.The simulation is also extended to analyze an array of TTRs.Different regular and irregular waves are considered.The behaviors of different cylinders are presented.The results show that it is important to consider the specific configurations of the tensioner and TTRs,which may lead to obviously different response behaviors,compared with those from a simplified model.

Multi-dimensional Simulation of Phase Change by a 0D-2D Model Coupling via Stefan Condition

Considering phase changes associated with a high-temperature molten material cooled down from the outside,this work presents an improvement of the modelling and the numerical simulation of such processes for an application pertaining to the safety of light water nuclear reactors.Postulating a core meltdown accident,the behaviour of the core melt(aka corium)into a steel vessel is of tremendous importance when evaluating the vessel integrity.Evaluating correctly the heat fluxes requires the numerical simulation of the interaction between the liquid material and its solid counterpart which forms during the solidification process,but also may melt back.To simulate this configuration,encoun-tered in various industrial applications,one considers a bi-phase model constituted by a liquid phase in contact and interaction with its solid phase.The liquid phase may solidify in presence of low energetic source,while the solid phase may melt due to an intense heat flux from the high-temperature liquid.In the frame of the in-house legacy code,several simplifying assumptions(0D multi-layer discretization,instantaneous heat transfer via a quadratic temperature profile in solids)are made for the modelling of such phase changes.In the present work,these shortcomings are illustrated and further overcome by solving a 2D heat conduction model in the solid by a mixed Raviart-Thomas finite element method coupled to the liquid phase due to heat and mass exchanges through Stefan condition.The liquid phase is modeled with a 0D multi-layer approach.The 0D-liquid and 2D-solid mod-els are coupled by a Stefan like phase change interface model.Several sanity checks are performed to assess the validity of the approach on 1D and 2D academical configurations for which exact or reference solutions are available.Then more advanced situations(genu-ine multi-dimensional phase changes and an"industrial-like scenario")are simulated to verify the appropriate behavior of the obtained coupled simulation scheme.

A fast hybrid simulation approach of ion energy and angular distributions in biased inductively coupled Ar plasmas

In this work,a two-dimensional hybrid model,which consists of a bulk fluid module,a sheath module and an ion Monte-Carlo module,is developed to investigate the modulation of ion energy and angular distributions at different radial positions in a biased argon inductively coupled plasma.The results indicate that when the bias voltage amplitude increases or the bias frequency decreases,the ion energy peak separation width becomes wider.Besides,the widths of the ion energy peaks at the edge of the substrate are smaller than those at the center due to the lower plasma density there,indicating the nonuniformity of the ion energy distribution function(IEDF)along the radial direction.As the pressure increases from 1 to 10 Pa,the discrepancy of the IEDFs at different radial positions becomes more obvious,i.e.the IEDF at the radial edge is characterized by multiple low energy peaks.When a dual frequency bias source is applied,the IEDF exhibits three or four peaks,and it could be modulated efficiently by the relative phase between the two bias frequencies.The results obtained in this work could help to improve the radial uniformity of the IEDF and thus the etching process.

2D Coupled 3D:A New Numerical Model for Dual - Structured - Aquifer System

This paper points out that a successful numerical simulation is to construct a correct conceptional model which is very dose to the natural condition. A new model, two dimensional coupled three dimensional model (2D -3D ) is presented in the Present paper,which is the most suitable one for the dual - structured - aquifer system. An example of Wenyinghu area is shown.By using the 2D-3D model, a satisfied result of the simulated area is achieved.

Mathematical model for flood routing in Jingjiang River and Dongting Lake network

The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional （l-D） mathematical model for flood routing in the river network Of the Jingjiang River and Dongting Lake using the explicit finite volume method. Based on observed data during the flood periods in 1996 and 1998, the model was calibrated and validated, and the results show that the model is effective and has high accuracy. In addition, the one-dimensional mathematical model for the river network and the horizontal two-dimensional （2-D） mathematical model for the Jingjiang flood diversion area were coupled to simulate the flood process in the Jingjiang River, Dongting Lake, and the Jingjiang flood diversion area. The calculated results of the coupled model are consistent with the practical processes. Meanwhile, the results show that the flood diversion has significant effects on the decrease of the peak water level at the Shashi and Chenjiawan hydrological stations near the flood diversion gates, and the effect is more obvious in the downstream than in the upstream.

考虑不同水流交换模式的城市洪涝一维二维双向耦合模型

为准确模拟城市洪涝过程,以地表二维流动模型和SWMM一维管流模型为基础,同时考虑地表径流与地下管流交换的3种模式,构建了城市地表与地下管流双向耦合的水动力学模型。采用水槽试验算例和理论算例对耦合模型进行验证,并将耦合模型应用到英国Glasgow城市街区,分析排水管网和不同地表地下水流交换模式对城市洪涝过程的影响。结果表明:模型在试验算例和理论算例的模拟中均具有较好的精度和可靠性,模型能够准确地模拟具有排水管网的城市洪涝演进过程;与无排水系统相比,检查井简化法、雨水口法和雨水口-检查井法3种水流交换模式下Glasgow城市街区模拟的最大淹没面积分别减少9.3%、23.2%和24.5%,其中对重度积水的消减作用更显著,淹没面积分别减少43.6%、79.9%和80.9%;检查井简化法的消减作用要远小于雨水口法和雨水口-检查井法,后两者差异较小。雨水口法和雨水口-检查井法比较符合实际情况,且雨水口-检查井法的计算效率更高更简单,因此,在城市洪涝模拟中采用雨水口-检查井法考虑地表径流与地下管流交换过程更符合实际。

ONE-AND TWO-DIMENSIONAL COUPLED HYDRODYNAMICS MODEL FOR DAM BREAK FLOW

1-D and 2-D mathematical models for dam break flow were established and verified with the measured data in laboratory. The 1-D and 2-D models were then coupled, and used to simulate the dam break flow from the reservoir tail to the dam site, the propagation of dam break waves in the downstream channel, and the submergence of dam break flow in the downstream town with the hydrodynamics method. As a numerical example, the presented model was employed to simulate dam break flow of a hydropower station under construction. In simulation, different dam-break durations, upstream flows and water levels in front of dam were considered, and these influencing factors of dam break flow were analyzed, which could be referenced in planning and designing hydropower stations.

Quasi-3D Numerical Simulation of Tidal Hydrodynamic Field

Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.

Coupled thermo-hydro-mechanical simulation of CO2 enhanced gas recovery with an extended equation of state module for TOUGH2MP-FLAC3D

As one of the most important ways to reduce the greenhouse gas emission,carbon dioxide（CO2）enhanced gas recovery（CO2-EGR） is attractive since the gas recovery can be enhanced simultaneously with CO2sequestration.Based on the existing equation of state（EOS） module of TOUGH2 MP,extEOS7C is developed to calculate the phase partition of H2O-CO2-CH4-NaCl mixtures accurately with consideration of dissolved NaCI and brine properties at high pressure and temperature conditions.Verifications show that it can be applied up to the pressure of 100 MPa and temperature of 150℃.The module was implemented in the linked simulator TOUGH2MP-FLAC3 D for the coupled hydro-mechanical simulations.A simplified three-dimensional（3D）1/4 model（2.2 km×1 km×1 km） which consists of the whole reservoir,caprock and baserock was generated based on the geological conditions of a gas field in the North German Basin.The simulation results show that,under an injection rate of 200,000 t/yr and production rate of 200,000 sm3/d,CO2breakthrough occurred in the case with the initial reservoir pressure of 5 MPa but did not occur in the case of 42 MPa.Under low pressure conditions,the pressure driven horizontal transport is the dominant process;while under high pressure conditions,the density driven vertical flow is dominant.Under the considered conditions,the CO2-EGR caused only small pressure changes.The largest pore pressure increase（2 MPa） and uplift（7 mm） occurred at the caprock bottom induced by only CO2injection.The caprock had still the primary stress state and its integrity was not affected.The formation water salinity and temperature variations of ±20℃ had small influences on the CO2-EGR process.In order to slow down the breakthrough,it is suggested that CO2-EGR should be carried out before the reservoir pressure drops below the critical pressure of CO2.

Applying Deep Learning Models to Mouse Behavior Recognition

In many animal-related studies, a high-performance animal behavior recognition system can help researchers reduce or get rid of the limitation of human assessments and make the experiments easier to reproduce. Recently, although deep learning models are holding state-of-the-art performances in human action recognition tasks, these models are not well-studied in applying to animal behavior recognition tasks. One reason is the lack of extensive datasets which are required to train these deep models for good performances. In this research, we investigated two current state-of-the-art deep learning models in human action recognition tasks, the I3D model and the R(2 + 1)D model, in solving a mouse behavior recognition task. We compared their performances with other models from previous researches and the results showed that the deep learning models that pre-trained using human action datasets then fine-tuned using the mouse behavior dataset can outperform other models from previous researches. It also shows promises of applying these deep learning models to other animal behavior recognition tasks without any significant modification in the models’ architecture, all we need to do is collecting proper datasets for the tasks and fine-tuning the pre-trained models using the collected data.

Effects of size and location of distal tear on hemodynamics and wave propagation in type B aortic dissection

The type B aortic dissection(TBAD)is a perilous disease with high morbidity and mortality rates.The hemodynamics of TBAD in different scenarios has been widely studied by computational fluid dynamics(CFD)research.However,the flow pattern and wave propagation characteristics in the cardiovascular system with TBAD are not yet clear,and the effect of the distal tear is still unknown.In this work,a onedimensional(1D)cardiovascular system model coupling with a zero-dimensional(0D)lumped-parameter model is introduced to study the hemodynamics and wave propagation in the cardiovascular system.The results show that the proposed 0D-1D method well captures the oscillation and retrograde characteristics for the flow in the false lumen(FL),and the smaller distal tear damps the retrograde flow.Besides,the distal tear should also be paid attention to,and the wave intensity(WI)can be used as an access mark of the degree of the aortic dissection(AD).

Pressure Effects on Spectra of Tunable Laser Crystal GSGG： Cr^3＋ IV： Pressure—Induced Shifts of R1 Line, R2 Line, and U Band at 300 K

By means of both a theory for pressure-induced shifts(PS) energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction(EPIP.the pure electronic PS and the PS due to EPI of R1 line,R2 line,and U band of GSGG:Cr^3+ at 300 K have been calculated,respectively.The calcualted results are in good agreement with all the experimental data.Their physical origins have also been explained.It is found that the mixingdegree of t2^2(^3T1)e^4T2) and |t2^3 3E>base-wavefunctions in the wavefunctions of R1 level of GSGG:Cr^3+ at 300K is remarkable under normal pressure,and the mixing-degree rapidly decreases with increasing pressure.The change of the mixing-degree with pressure plays a key role not only for the pure electronic'PS of R1 line and R2 line but also the PS of R1 line and R2 line due to EPI.The pressure-dependent behaviors of the pure electronic 'PS of R1 line(or R2 line) and the PS of R1 line(or R2 line) due to EPI are quite different.It is the combined effect of them that gives rise to the total PS of R1 line(or R2 line).In the range of about 15 kar-45kbar,the mergence and /or order-reversal between t2^2(3T1)e^4T2 levels and t2^32T1 levels take place,which cause the fluctuation of the rate of PS for t2^2(3T1)e^4T2(or t2^32T1) with pressure,At 300K,both the temperature-dependent contribution to R1 line(Or R2 line or U band) from EPI and the temperature-independent one are important.

基于一二维耦合模型和水库调度的长江宜宾河段洪水遭遇与淹没分析

【目的】宜宾市地处金沙江与岷江汇合处,且有横江、南广河及其他重要支流汇入,因此洪水遭遇组合复杂,且受金沙江下游向家坝-溪洛渡等梯级水库调度影响明显,其水文水动力计算对下游各城镇河段防洪规划及减灾政策制定具有重要意义。【方法】通过构建一二维水动力学耦合数学模型,采用实测洪水验证的分析方法对长江宜宾河段(含重要支流汇入段)的洪水组合进行分析,选取了1961年、1966年两个典型年并对比有无金沙江下游梯级水库调洪的影响,计算各河段和沿岸城镇100 a、50 a及20 a一遇的洪水淹没。【结果】结果表明:(1)当发生超标洪水时,城区主要洪水漫溢淹没分布在宜宾的安边镇、柏溪街道,翠屏区西郊街道以及岷江菜坝镇飞机坝段。(2)不管是1961典型年(岷江为主要来水)还是1966典型年(金沙江为主要来水),岷江流域均受灾较重;其中西郊街道和大观楼街道的洪水主要受金沙江来水和岷江洪水顶托作用明显;岷江漫溢洪水为宜宾城区外洪的主要来源,岷江是宜宾市的防洪重点。【结论】结合防洪工程分布及现有堤防建设情况,菜坝镇飞机坝片区现有的20 a一遇洪水的堤防无法满足实际防洪标准需求;西郊街道滨江公园和备战码头,由于未形成防洪封闭圈,城区局部地区仍处于不设防状态;柏溪镇堤防防洪标准20 a一遇偏低,黑河(柏树溪)受到金沙江回水影响会造成柏溪镇严重洪灾。金沙江在向家坝水库的调蓄作用下,即使发生100 a或超过50 a一遇超标洪水,中心城区均不超过40 a一遇,宜宾城区受金沙江洪水影响相对较小,受岷江回水影响较大。

A COUPLED 1-D AND 2-D CHANNEL NETWORK MATHEMATICAL MODEL USED FOR FLOW CALCULATIONS IN THE MIDDLE REACHES OF THE YANGTZE RIVER

A coupled one-dimensional （1-D） and two-dimensional （2-D） channel network mathematical model is proposed for flow calculations at nodes in a channel network system in this article. For the 1-D model, the finite difference method is used to discretize the Saint-Venant equations in all channels of a looped network. The Alternating Direction Implicit （ADI） method is adopted for the 2-D model at the nodes. In the coupled model, the 1-D model provides a good approximation with small computational effort, while the 2-D model is applied for complex topography to achieve a high accuracy. An Artificial Neural Network （ANN.） method is used for the data exchange and the connectivity between the 1-D and 2-D models. The coupled model is applied to the Jingjiang-Dongting Lake region, to simulate the tremendous looped channel network system, and the results are compared with field data. The good agreement shows that the coupled hydraulic model is more effective than the conventional 1-D model.

A 2D/3D COUPLED MODEL FOR WAVE FORCES ON MOORED SHIPS IN A HARBORA

For the purpose of time-domain calculation of wave forces on moored ships ina harbor, the 2D/3D coupled numerical model was developed, in which the horizontally 2Dshallow-water wave model based on the improved Boussinesq equations was adopted for the calculationin the wide region located far from the ships while the 3D numerical model based on theReynolds-Averaged Navier-Stokes (RANS) equations was used in the limited region adjacent to theships. The domain connection technique with overlaping region between different model regions wasapplied and examined. It is shown that the present partially 3D hybrid model saves calculation timesignificantly compared to the full 3D model for the whole region and is capable of reproducing thecharacteristics of 3D and complicated flows around the ships and 3D hydrodynamic loads on them,which cannot be reproduced by the 2D model alone.

HEC-RAS和MIKE11模型河床糙率应用比较研究

近十几年来,科学技术的发展为水流运动的数学模型研究提供了有利条件,并出现了大批商用软件。HEC-RAS和MIKE11作为最常用的一维水流模型商用计算软件,被广泛用于计算不同水文条件、工程前后河段的水流运动,并均有较好的计算结果。然而,两种软件从模型假设、建立到运行等方面存在着许多差异。本文着重以HEC-RAS和MIKE11对河道糙率的不同计算方法为出发点,利用赣江外洲至南昌段实测地形和水文资料进行计算,然后对计算结果进行比较分析,得到两种软件的联系与区别。

地表河网-地下水流系统耦合模拟Ⅰ:模型

本文通过采用联立求解地表河流一维明渠非恒定渐变流与地下水拟三维非稳定流运动方程的技术路线,提出了地表河网与地下水流耦合模拟算法。该算法中地表河网流动分别由质量和动量守恒定律而建立的连续性方程和运动方程所组成;地下水流采用多层"拟三维"非稳定流模型,通过彼此间的水力联系,建立了地表河网-地下水流耦合模拟评价模型,该模型可用于地表水与地下水转化关系较为密切地区的水资源综合评价预测中。

潮汐动力场准三维值模拟

本文建立了适用于海岸潮汐动力环境模拟的准三维数学模型，其特点是在成功实现二维全流模型计算的同时，求解流速差值（即流速与其垂线平均值之差）方程组，从而获得潮流速的垂直分布，并使两者结果相一致。在验证计算和应用于复杂海域的研究计算中，数值结果不仅与分析解取得一致，而且与实测值符合较好，证明该模型是实用有效的。