scholarly journals Comparison and analysis of calculation of Bridge backwater based on Mike21 hydrodynamic model

2021 ◽  
Vol 233 ◽  
pp. 03043
Author(s):  
Jiang Chuan Liu ◽  
Zhu Qiu Hu ◽  
Mao Yuan Zhu
Keyword(s):  
Theoretical Basis ◽  
Impact Analysis ◽  
Navier Stokes ◽  
Efficiency Coefficient ◽  
Navier Stokes Equation ◽  
The Real ◽  
Comparison And Analysis ◽  
Simulation Results ◽  
The Difference ◽  
Local Water

The construction of bridges and other structures across the river will affect the flood discharge capacity and local water potential of the river.Based on navier-Stokes equation of MIKE21FM hydrodynamic module, this paper carries out two-dimensional numerical simulation of part of Shixi River. By optimizing the grid near the piers to reduce the difference brought by the terrain generalized grid of the real river, it simulates and analyzes the length of the curve of yong-high and Yong-water under different flood frequencies,the Nash-Sutcliffe efficiency coefficient and relative error analysis are used to verify the rationality of the results. The simulation results can accurately reflect the real changes of river water level, It provides a theoretical basis for flood impact analysis.

A Study of Bifurcation Design Used in CD-ELISA Micro-Fluidic Platform

2010 ◽  
Author(s):  
Samuel I. En Lin
Keyword(s):  
Coriolis Force ◽  
Clinical Diagnostics ◽  
Biological Molecules ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Safety Testing ◽  
Micro Channels ◽  
Simulation Results ◽  
Incompressible Navier Stokes Equation ◽  
Detection And Quantification

Enzyme-linked immunosorbent assays (ELISA), one of the most common immunoassays, is widely used for detection and quantification of chemical and biological molecules and is becoming more and more important in clinical diagnostics, food safety testing, and environmental monitoring. A major challenge in developing the CD-ELISA is to split the flow (e.g., bio-reagents) evenly on the micro-channels. The Coriolis force resultant from CD rotation can disturb the flow in the splitter region and thus cause the failure mode in delivering the solution from each reservoir in a pre-specified manner. In this study, we investigate on the effects of inlet pressure and Coriolis force on the splitting ratio under two splitter structures. The analysis is based on the incompressible Navier-Stokes equation and the simulation results agree well with our experimental work.

scholarly journals First simulation results of Titan's atmosphere dynamics with a global 3-D non-hydrostatic circulation model

2006 ◽  
Vol 24 (8) ◽  
pp. 2115-2129 ◽  
Author(s):  
I. V. Mingalev ◽  
V. S. Mingalev ◽  
O. V. Mingalev ◽  
B. Kazeminejad ◽  
H. Lammer ◽  
...  
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Wind Speeds ◽  
Neutral Gas ◽  
Complex Simulation ◽  
First Results ◽  
Simulation Results ◽  
Model Region

Abstract. We present the first results of a 3-D General Circulation Model of Titan's atmosphere which differs from traditional models in that the hydrostatic equation is not used and all three components of the neutral gas velocity are obtained from the numerical solution of the Navier-Stokes equation. The current version of our GCM is, however, a simplified version, as it uses a predescribed temperature field in the model region thereby avoiding the complex simulation of radiative transfer based on the energy equation. We present the first simulation results and compare them to the results of existing GCMs and direct wind observations. The wind speeds obtained from our GCM correspond well with data obtained during the Huygens probe descent through Titan's atmosphere. We interpret the most unexpected feature of these data which consist of the presence of a non-monotonicity of the altitude profile of the zonal wind speed between 60 and 75 km.

SIMULASI ARUS LALU LINTAS DENGAN MENGGUNAKAN KECEPATAN MODEL KERNER KONHÄUSER

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Yessy Yusnita
Keyword(s):  
Finite Difference ◽  
Flow Velocity ◽  
Traffic Flow ◽  
Stokes Equation ◽  
Navier Stokes ◽  
Real Situation ◽  
Navier Stokes Equation ◽  
Conservation Equations ◽  
The Real ◽  
Road Section

In the real situation, the vehicle flow velocity on a road are not always in an equilibrium situation. The Kerner Konhäuser model illustrate that the vehicle flow velocity is an application of the Navier Stokes equation. The model is solved numerically by using the finite difference approach to calculate the flow velocity. The result will be used in solve the conservation equations in order to the density of traffic flow. The Simulation is carried on a single-lane road section. The results show that the vehicle flow velocity will increase if the density of the traffic flow decreases and the vehicle flow velocity will decrease if the density of traffic flow increases.

INFLUENCE OF ELECTROLYTE COMPOSITION AND OVERHEATING ON THE SIDELEDGE IN THE ALUMINUM CELL

2018 ◽  
pp. 24-30 ◽  
Author(s):  
V. V. Stakhanov ◽  
A. A. Redkin ◽  
Yu. P. Zaikov ◽  
A. E. Galashev
Keyword(s):  
Boussinesq Approximation ◽  
Navier Stokes ◽  
Transfer Coefficients ◽  
Navier Stokes Equation ◽  
Cryolite Ratio ◽  
Heat Transfer Coefficients ◽  
Aluminum Smelting ◽  
Block Wall ◽  
The Difference ◽  
Aluminum Cell

The paper presents a theoretical study conducted to investigate the effect that the chemical composition of electrolyte and its overheating have on the size of sideledge formed in an aluminum smelting bath. Three electrolyte compositions were chosen: (1) sodium cryolite with the cryolite ratio CR = 2,7; (2) cryolite CR = 2,7 + 5 wt.% CaF2; (3) cryolite CR = 2,7 + 5 wt.% CaF2 + 5 wt.% Al2О3. The electrolyte liquidus overheating temperatures were 5, 10, 15 and 20 °C. Calculations were performed using the finite element method. A simplified design of an aluminum cell was used with a prebaked anode. The temperature field was calculated using a mathematical model based on the Boussinesq approximation, which contains the Navier–Stokes equation as well as thermal conductivity and incompressibility equations. The key role of electrolyte overheating in sideledge formation was established. The resulting sideledge profile depends on the heat transfer coefficients and thermophysical properties of materials. The smallest sideledge thickness with the same electrolyte overheating was observed in cryolite composition 3, and the profiles of the formed sideledge for samples 1 and 2 were nearly the same. The thickness of the sideledge formed with a 5 degree overheating exceeded 7 cm and the difference in temperature between the sideledge in contact with electrolyte and the side block wall was 20–25 degrees. It was found that the virtually total disappearance of the sideledge occurs at electrolyte liquidus overheating by 20 degrees.

Experimental velocity profiles in laminar flow around spheres at intermediate Reynolds numbers

1975 ◽  
Vol 68 (3) ◽  
pp. 591-608 ◽  
Author(s):  
L. E. Seeley ◽  
R. L. Hummel ◽  
J. W. Smith
Keyword(s):  
Laminar Flow ◽  
Free Stream ◽  
Reynolds Numbers ◽  
Separation Point ◽  
Navier Stokes ◽  
Similar Data ◽  
Navier Stokes Equation ◽  
Stream Functions ◽  
The Difference ◽  
Grid Points

Normal and tangential velocities in the boundary layer and out into the free stream have been obtained using a non-disturbing flow visualization technique for uniform laminar flow around a sphere. The non-similar data are available in tables at 2.5° intervals from 20° from the front to about 15° past the separation point a t Reynolds numbers of 290, 750, 1300 and 3000. Stream functions calculated by LeClair using a numerical solution of the Navier-Stokes equation at Re 21 300 are not in good agreement with measured values from 30° to 60°, but are in much better agreement around the separation point. Too few grid points near the sphere where the tangential velocities rise to a maximum above free-stream values may account for the difference.

Analytic Solution for Microscale Poiseuille Flow Based on Super-Burnett Equations

2013 ◽  
Vol 705 ◽  
pp. 609-615
Author(s):  
Cheng Qian Song ◽  
Xie Yuan Yin ◽  
Feng Hua Qin
Keyword(s):  
Poiseuille Flow ◽  
Constitutive Relations ◽  
Slip Boundary Condition ◽  
Continuous Model ◽  
Analytic Solutions ◽  
High Order ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Slip Boundary ◽  
The Difference

The previous studies show that the transverse distribution of pressure and temperature in microscale Poiseuille flow cannot be predicted by Navier-Stokes equation with the slip boundary condition. In this paper, we analyzed the planar microchannel force-driven Poiseuille flow by high order continuum model. The super-Burnett constitutive relations were used and the nonlinear ordinary differential Equations of higher-orders were obtained by the hypothesis of parallel flow. With a perturbations theory, we linearized the equations and obtained the analytic solutions. The results show that the solutions can capture the temperature dip which is the same as the DSMC result. However, we also find that the temperature profile near the wall does always not match with the DSMC result. Especially, the difference in the qualitative exists when the Knudsen number is large enough. The non-equilibrium effect near the wall such as Knudsen layer can not be described entirely by continuous model even with high order constitutive relations and this confines the extension of the continuous model such as super-Burnett one.

Flow and Stress Induced Cavitation in a Journal Bearing With Axial Throughput

2001 ◽  
Vol 123 (4) ◽  
pp. 742-754 ◽  
Author(s):  
A. Pereira ◽  
G. McGrath ◽  
D. D. Joseph
Keyword(s):  
Reynolds Number ◽  
Pressure Gradient ◽  
Journal Bearing ◽  
Maximum Tensile Stress ◽  
Navier Stokes ◽  
Relative Pressure ◽  
Navier Stokes Equation ◽  
Open Region ◽  
The Difference ◽  
The Stability

The problem of predicting flow between rotating eccentric cylinders with axial throughput is studied. The system models a device used to test the stability of emulsions against changes in drop size distribution. The analysis looks for the major variation in flow properties which could put an emulsion at risk due to coalescence or breakage and finds the most likely candidate in the pressure gradient defined as the ratio of the difference between the maximum and minimum pressure to the arc length between the difference. The axial throughput is modeled by flow driven by a constant pressure gradient. The flow is calculated from the Navier-Stokes equation using the code SIMPLER (Patankar 1980). The effects of inertia at values typical for the device are studied. Several eccentricities and different rotational speeds are computed to sample the changes in flow and stress parameters in the idealized device for typical conditions. The numerical analysis is validated against the lubrication approximation in the low Reynolds number case. Conditions for stress induced cavitation are evaluated. The flow is completely determined by a Reynolds number, an eccentricity ratio and a dimensionless pressure gradient and all computed results are either presented or can be easily expressed in terms of these dimensionless parameters. The effect of inertia is to shift the eddy or re-circulation zone which develops in the more open region of the gap toward the region of low relative pressure; the zero of the relative pressure migrates away from the center and the distribution breaks the skew symmetry of the Stokes flow solution. The state of stress in the journal bearing is analyzed and a cavitation criterion based on the maximum tensile stress is compared with the traditional criterion based on pressure.

Simulations of Micro Gas Flows by the DS-BGK Method

2011 ◽  
Author(s):  
Jun Li
Keyword(s):  
Mean Free Path ◽  
Navier Stokes ◽  
Gas Flows ◽  
Dominant Effect ◽  
Dsmc Method ◽  
Low Velocity ◽  
Navier Stokes Equation ◽  
Reflection Model ◽  
Accommodation Coefficients ◽  
Simulation Results

For gas flows in micro devices, the molecular mean free path is of the same order as the characteristic scale making the Navier-Stokes equation invalid. Recently, some micro gas flows are simulated by the DS-BGK method, which is convergent to the BGK equation and very efficient for low-velocity cases. As the molecular reflection on the boundary is the dominant effect compared to the intermolecular collisions in micro gas flows, the more realistic boundary condition, namely the CLL reflection model, is employed in the DS-BGK simulation and the influence of the accommodation coefficients used in the molecular reflection model on the results are discussed. The simulation results are verified by comparison with those of the DSMC method as criteria.

A simple hydromechanical approach for simulating squirt-type flow

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. D335-D344 ◽  
Author(s):  
Beatriz Quintal ◽  
J. Germán Rubino ◽  
Eva Caspari ◽  
Klaus Holliger
Keyword(s):  
Fluid Flow ◽  
Spatial Patterns ◽  
Elastic Solid ◽  
Viscous Friction ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Perfect Agreement ◽  
Type Flow ◽  
The Difference ◽  
Biot’S Equations

The deformations caused by an acoustic wavefield in subsurface rock can induce fluid flow within hydraulically interconnected mesoscopic fractures, from one fracture into the other. The viscous friction associated with this squirt-type fluid flow parallel to the fracture walls results in energy dissipation and velocity dispersion. We have developed a quasi-static hydromechanical approach that is suitable for simulating squirt-type flow in the mesoscopic scale range and microscopic squirt flow. Our approach couples Navier-Stokes equation with Hooke’s law to describe the laminar flow of a viscous compressible fluid in conduits embedded in an elastic solid background. Results from the proposed method were compared with those obtained with Biot’s equations for a model containing interconnected mesoscopic fractures embedded in a background of very low porosity and permeability. Despite significant differences in the flow and dissipation spatial patterns, we have observed an essentially perfect agreement of the attenuation and modulus dispersion characteristics predicted by the two approaches. The difference in the flow and dissipation spatial patterns are associated with the “upscaling” inherent to Biot’s equations and, correspondingly, with differing boundary conditions at the fracture walls. Our results demonstrate that the proposed hydromechanical approach can provide additional insights on the physics of squirt-type flow in the mesoscopic and microscopic scale ranges.

scholarly journals Some remarks on a quasi-steady-state approximation of the Navier-Stokes equation

1988 ◽  
Vol 29 (4) ◽  
pp. 440-447
Author(s):  
John R. Cannon ◽  
George H. Knightly
Keyword(s):  
Steady State ◽  
Stokes Equation ◽  
Small Body ◽  
Navier Stokes ◽  
Quasi Steady State ◽  
Navier Stokes Equation ◽  
State Approximation ◽  
Steady State Approximation ◽  
The Difference ◽  
Image Position

AbstractA quasi-steady-state apprcncimation to the Navier-Stokes equation is the corresponding equation with nonhomogeneous forcing term f(x, t), but with the term Vt deleted. For solutions that are zero on the boundary, the difference z between the solution of the Navier-Stokes equation and the solution of this quasi-steady-state approximation is estimated in the L2 norm ║z║ with respect to the spatial variables. For sufficiently large viscosity or sufficiently small body force f, the inequalityholds for 0 < t ≤ T and certain real numbres C, β > 0.

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