One-dimensional hydrodynamic model accounting for tidal effect

2012 ◽  
Vol 43 (1-2) ◽  
pp. 113-122 ◽  
Author(s):  
Xiaoqin Zhang ◽  
Weimin Bao ◽  
Simin Qu ◽  
Zhongbo Yu
Keyword(s):  
Hydrodynamic Model ◽  
Dynamic Effect ◽  
Momentum Equation ◽  
Tidal Effect ◽  
Flood Routing ◽  
One Dimensional ◽  
Tidal Rivers ◽  
Saint Venant Equations ◽  
Tidal Reach ◽  
The One

Tidal effect has a significant impact on flood routing in tidal rivers, conceptually taking on a resistant effect during flood tide and a dynamic effect during ebb tide. Two expressions were developed to reflect the tidal effect in this study, which consisted of the tidal wave velocity, the change rate of tidal level and the change in channel width. By incorporating the expressions into the momentum equation of the one-dimensional (1D) Saint-Venant equations, we propose that there are two types of momentum equations accounting for tidal effect. Based on the continuity equation and proposed momentum equations, two types of 1D hydrodynamic model for tidal rivers (namely the SVN-1 and -2 models) were constructed. In the case study, these models were applied to the tidal reach of the Qiantang River in China. The simulation results show that the SVN-1 and -2 models can obtain better accuracy than the SVN model based on the standard Saint-Venant equations, and that the SVN-1 model performs better than the SVN-2 model. Furthermore, the SVN-1 model can effectively capture water-level fluctuation, indicating that the expression employed is capable of accounting for tidal effect.

scholarly journals Comparison of numerical schemes of river flood routing with an inertial approximation of the Saint Venant equations

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Alice César Fassoni-Andrade ◽  
Fernando Mainardi Fan ◽  
Walter Collischonn ◽  
Artur César Fassoni ◽  
Rodrigo Cauduro Dias de Paiva
Keyword(s):  
Numerical Stability ◽  
Flood Routing ◽  
Computational Time ◽  
Numerical Schemes ◽  
Time Step ◽  
Simple Formulation ◽  
One Dimensional ◽  
Saint Venant Equations ◽  
Original Scheme ◽  
The One

ABSTRACT The one-dimensional flow routing inertial model, formulated as an explicit solution, has advantages over other explicit models used in hydrological models that simplify the Saint-Venant equations. The main advantage is a simple formulation with good results. However, the inertial model is restricted to a small time step to avoid numerical instability. This paper proposes six numerical schemes that modify the one-dimensional inertial model in order to increase the numerical stability of the solution. The proposed numerical schemes were compared to the original scheme in four situations of river’s slope (normal, low, high and very high) and in two situations where the river is subject to downstream effects (dam backwater and tides). The results are discussed in terms of stability, peak flow, processing time, volume conservation error and RMSE (Root Mean Square Error). In general, the schemes showed improvement relative to each type of application. In particular, the numerical scheme here called Prog Q(k+1)xQ(k+1) stood out presenting advantages with greater numerical stability in relation to the original scheme. However, this scheme was not successful in the tide simulation situation. In addition, it was observed that the inclusion of the hydraulic radius calculation without simplification in the numerical schemes improved the results without increasing the computational time.

scholarly journals Comparison of West Balkan adult trout habitat predictions using a Pseudo-2D and a 2D hydrodynamic model

2016 ◽  
Vol 48 (6) ◽  
pp. 1697-1709 ◽  
Author(s):  
Christina Papadaki ◽  
Vasilis Bellos ◽  
Lazaros Ntoanidis ◽  
Elias Dimitriou
Keyword(s):  
Hydrodynamic Model ◽  
River Discharge ◽  
Environmental Flow ◽  
Two Dimensional ◽  
Habitat Models ◽  
One Dimensional ◽  
2D Flow ◽  
A Cell ◽  
The One ◽  
Water Depths

Abstract Hydraulic-habitat models combine the dynamic behavior of river discharge with geomorphological and ecological responses. In this study, they are used for estimating environmental flow requirements. We applied a Pseudo-two-dimensional (2D) model based on the one-dimensional (1D) HEC-RAS model and an in-house 2D (FLOW-R2D) hydrodynamic model to a section of river for several flows in respect of summer conditions of the study reach, and compared the results derived from the models in terms of water depths and velocities as well as habitat predictions in terms of weighted usable area (WUA). In general, 2D models are more promising in habitat studies since they quantify spatial variations and combinations of flow patterns important to stream flora and fauna in a higher detail than the 1D models. Relationships between WUA and discharge for the two models were examined, to compare the similarity as well as the magnitude of predictions over the modelled discharge range. The models predicted differences in the location of maxima and changes in variation of velocity and water depth. Finally, differences in spatial distribution (in terms of suitability indices and WUA) between the Pseudo-2D and the fully 2D modelling results can be considerable on a cell-by-cell basis.

GLOBAL WEAK SOLUTIONS OF THE ONE-DIMENSIONAL HYDRODYNAMIC MODEL FOR SEMICONDUCTORS

1993 ◽  
Vol 03 (06) ◽  
pp. 759-788 ◽  
Author(s):  
F. JOCHMANN
Keyword(s):  
Weak Solution ◽  
Viscosity Solutions ◽  
Hydrodynamic Model ◽  
Global Weak Solution ◽  
Limit Problem ◽  
Young Measures ◽  
P System ◽  
Compensated Compactness ◽  
One Dimensional ◽  
The One

The existence of a global weak solution of the one-dimensional hydrodynamic model for semiconductors is proved by the method of artificial viscosity and the theory of compensated compactness. The system is first regularized and global viscosity-solutions are constructed. Letting the viscosity-parameter tend to zero, we obtain a sequence of viscosity-solutions converging in L∞-weak* to a weak solution of the one-dimensional p-system from isoentropic gas dynamics with an electric field term and momentum relaxation. Since the equations are nonlinear and the convergence is only weak, the theory of Young-measures and compensated compactness is applied to obtain a weak solution of the limit problem.

Verification of a Finite Element Method for Solving One-Dimensional Equations of Blood Flow Incorporating a Viscoelastic Wall Model

2009 ◽  
Author(s):  
Rashmi Raghu ◽  
Charles A. Taylor
Keyword(s):  
Blood Flow ◽  
Surgical Planning ◽  
Computational Cost ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Cross Sectional ◽  
One Dimensional ◽  
The One ◽  
Modeling Flow ◽  
Three Dimensional Simulations

The one-dimensional (1-D) equations of blood flow consist of the conservation of mass equation, balance of momentum equation and a wall constitutive equation with arterial flow rate, cross-sectional area and pressure as the variables. 1-D models of blood flow enable the solution of large networks of blood vessels including wall deformability. Their level of detail is appropriate for applications such as modeling flow and pressure waves in surgical planning and their computational cost is low compared to three-dimensional simulations.

scholarly journals Interactions between Lake-Level Fluctuations and Waterlogging Disasters around a Large-Scale Shallow Lake: An Empirical Analysis from China

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 318 ◽  
Author(s):  
Zongzhi Wang ◽  
Kun Wang ◽  
Kelin Liu ◽  
Liang Cheng ◽  
Lihui Wang ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Lake Level ◽  
Large Scale ◽  
Drainage System ◽  
Flood Routing ◽  
Lake Basin ◽  
Rainfall Events ◽  
One Dimensional ◽  
Lake Level Fluctuations ◽  
Pumping Stations

Waterlogging disasters in the lakeside areas of shallow lakes that located in plain regions are sensitive to lake-level fluctuations. However, there are very few studies on the influences of lake-level fluctuations on waterlogged lakeside areas from a large lake basin perspective. This paper proposes an integrated hydrodynamic model employing the MIKE software to contribute to the existing literature by filling the gap constituted by the lack of an estimation of the impacts of lake-level fluctuations on waterlogging disasters by relevant models. First, a coupled one-dimensional and two-dimensional hydrodynamic model is established to simulate the waterlogging routing in the lakeside area around Nansi Lake (NL) in addition to the flood routing in NL and its tributaries. Second, the model is calibrated and verified by two measured flood events in July 2007 and July 2008; the results indicate that the model can correctly simulate the drainage process of pumping stations in the lakeside area, as well as the interactions between the waterlogging drainage and lake-level fluctuations. Third, the process of waterlogging in the lakeside area of NL is simulated under different rainfall events and initial lake-level conditions. Fourth, based on the results of the model, this paper illustrates the influences of lake-level fluctuations on the waterlogged area around the lake, as well as the different responses of waterlogging in different areas to lake-level fluctuations in NL and the main cause for these differences. Finally, based on the results of the model, this paper presents some implications for waterlogging simulations and drainage system design.

scholarly journals The Modified One-Dimensional Hydrodynamic Model Based on the Extended Chezy Formula

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1743
Author(s):  
Junwei Zhou ◽  
Weimin Bao ◽  
Yu Li ◽  
Li Cheng ◽  
Muxi Bao
Keyword(s):  
Hydrodynamic Model ◽  
Calibration Method ◽  
Friction Model ◽  
Flood Routing ◽  
Flow Depth ◽  
Parameter Calibration ◽  
Simulation Test ◽  
One Dimensional ◽  
Hydraulic Experiment ◽  
Peak Value

Although steady uniform friction formulas have been introduced to the framework of a one-dimensional (1D) hydrodynamic model for centuries, the error of friction calculation inevitably undermines the performance of flood routing. Based on successful results of unsteady channel friction research studies, a newly proposed unsteady friction model is introduced to establish a modified 1D hydrodynamic model (namely, the modified SVN model). With the help of a carefully designed parameter calibration method, the performance of the modified SVN model was compared with that of the original SVN model in a simulation test for a hydraulic experiment. This study’s results revealed that compared with the original SVN model, the modified SVN model could achieve a better simulation in both the flow depth and the sectional averaged velocity simulations. Furthermore, it could reduce the peak value error and the time-at-peak error as well, indicating that the use of an unsteady friction model can efficiently improve the performance of a 1D hydrodynamic model.

A Finite-Element Simulation of Pulsatile Flow in Flexible Obstructed Tubes

1982 ◽  
Vol 104 (2) ◽  
pp. 119-124 ◽  
Author(s):  
E. Rooz ◽  
D. F. Young ◽  
T. R. Rogge
Keyword(s):  
Finite Element ◽  
Pulsatile Flow ◽  
Continuity Equation ◽  
Element Model ◽  
Momentum Equation ◽  
Cross Sectional ◽  
One Dimensional ◽  
Element Simulation ◽  
The One

A finite-element model for pulsatile flow in a straight flexible partially obstructed tube is developed. In the unobstructed sections of the tube the model considers the continuity equation, the one-dimensional momentum equation, and an equation of state relating tube cross-sectional area to pressure. For the obstructed region, a nonlinear relationship between the flow and the pressure drop across the stenosis is considered. The applicability of a model is checked by comparing predicted flow and pressure waveforms with corresponding in-vitro experimental measurements obtained on a mechanical system. These comparisons indicate that the model satisfactorily predicts pressures and flows under variety of frequencies of oscillation and stenosis severities.

scholarly journals A Method for the Prediction of Supersonic Compressor Blade Performance

1989 ◽  
Author(s):  
C. Freeman ◽  
N. A. Cumpsty
Keyword(s):  
Flow Instability ◽  
Pressure Rise ◽  
Momentum Equation ◽  
Compressor Blades ◽  
Direction Parallel ◽  
One Dimensional ◽  
Inlet Region ◽  
Small Force ◽  
Surge Line ◽  
The One

A simple model is used to calculate the flow in compressor blades with supersonic relative inlet flow. The one-dimensional model utilises the conservation of stagnation enthalpy, mass flow and momentum in the inlet region. The momentum equation is applied in the direction parallel to the blade surface at inlet and one of the fundamental simplifications adopted is that the projected area of the blades gives such a small force in this direction that a very simple approximation for it suffices. The model is able to predict the loss creation in the inlet region. The level of predicted loss agree well with measured values when the Mach numbers are sufficiently high for the inlet loss to dominate. Furthermore the correct trends of loss with incidence and blade speed are predicted. The pressure rise and flow can also be predicted when the correct deviation and meridional streamtube convergence are given. The method predicts trends usually seen in measurments: the narrowing of the useful operating range between choke and flow instability (surge) as blade speed is increased and a steepening of the surge line at the higher speeds.

Numerical simulation of A-type hydraulic jumps at positive steps

2000 ◽  
Vol 27 (4) ◽  
pp. 805-813 ◽  
Author(s):  
A Burcu Altan Sakarya ◽  
Nuray Denli Tokyay
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Jump ◽  
Integral Approach ◽  
Internal Boundary ◽  
Subcritical Flow ◽  
One Dimensional ◽  
A Value ◽  
Saint Venant Equations ◽  
The One ◽  
Positive Step

A numerical simulation of the A-type hydraulic jump at a positive step, which is an example of mixed supercritical-subcritical flow with a discontinuity at the channel bed, is given by using an integral approach. A gradually varied subcritical flow over a rectangular, horizontal, and prismatic channel with an abrupt bottom rise is considered as the initial condition. Then, the upstream depth is decreased to a value producing a supercritical flow and remaining unchanged during computations. The resulting unsteady flow is solved by using both the MacCormack and the dissipative two-four schemes for the one-dimensional, unsteady Saint-Venant equations. In the numerical simulation, the step is treated as an internal boundary. At the downstream and the internal boundaries, the method of characteristics is employed to compute the relevant parameters. The numerical simulation is verified by comparing the results with the available data and analytical methods.Key words: hydraulic jump, positive step, numerical simulation, internal boundary.

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