scholarly journals Comparative Analysis of the Erosion Mechanism of Different Profiles in the Arcuate Foreshore under Typhoon Action

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Zishen Chen ◽  
Jitao Yu
Keyword(s):  
Maximum Velocity ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Dynamic State ◽  
Coastal Current ◽  
Roll Force ◽  
Beach Profile ◽  
Radiation Stress ◽  
Water Flow Velocity ◽  
Comparison Results

The comparison results of three beach profile data repeatedly measured before and after the typhoon in Shuidong Bay, west Guangdong province which show that there are significant differences in beach profile erosion and response process. And the changes of beach profile can be divided into: strong downward overall low shoreline regressive type and overall slight erosion shoreline regressive type. Application of the modified mild-slope equation along three beach profile are simulated wave high reflection to the sea side, to the section vertical shore pressure gradient and including water roll force and radiation stress, the vertical shore forces one dimensional profile along the momentum conservation equation (radiation stress and water roll force) bottom friction and lateral mixing reaction between numerical solution, the momentum conservation equations of the wave increases the water flow velocity and section along the profile distribution of wave height and related forces. The analysis shows that the extent and difference of coastal erosion depend on the shoreline erosion mode stimulated by the maximum surge water of the coastal current and the maximum velocity of the coastal current and the dynamic state of the profile topography under the action of the profile location, morphology and incident wave elements.

scholarly journals INDOOR AIR TEMPERATURE DISTRIBUTION – AN ALTERNATIVE APPROACH TO BUILDING SIMULATION

2003 ◽  
Vol 2 (1) ◽  
Author(s):  
A. T. Franco ◽  
C. O. R. Negrão
Keyword(s):  
Temperature Distribution ◽  
Air Temperature ◽  
Indoor Air ◽  
Linear Equations ◽  
Three Dimensional ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Algebraic Equations ◽  
Conservation Of Energy ◽  
Energy Conservation Equation

The current paper presents a model to predict indoor air temperature distribution. The approach is based on the energy conservation equation which is written for a certain number of finite volumes within the flow domain. The magnitude of the flow is estimated from a scale analysis of the momentum conservation equation. Discretized two or three-dimensional domains provide a set of algebraic equations. The resulting set of non-linear equations is iteratively solved using the line-by-line Thomas Algorithm. As long as the only equation to be solved is the conservation of energy and its coefficients are not strongly dependent on the temperature field, the solution is considerably fast. Therefore, the application of such model to a whole building system is quite reasonable. Two case studies involving buoyancy driven flows were carried out and comparisons with CFD solutions were performed. The results are quite promising for cases involving relatively strong couplings between heat and airflow.

Static modeling and analysis of soft manipulator considering environment contact based on segmented constant curvature method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yinglong Chen ◽  
Wenshuo Li ◽  
Yongjun Gong
Keyword(s):  
Contact Force ◽  
Constant Curvature ◽  
Kinematic Model ◽  
Fluid Pressure ◽  
Conservation Equation ◽  
Detection Accuracy ◽  
Content Type ◽  
Comparison Results ◽  
Static Modeling ◽  
Soft Manipulator

Purpose The purpose of this paper is to estimate the deformation of soft manipulators caused by obstacles accurately and the contact force and workspace can be also predicted. Design/methodology/approach The continuum deformation of the backbone of the soft manipulator under contact is regarded as two constant curvature arcs and the curvatures are different according to the fluid pressure and obstacle location based on piecewise constant curvature framework. Then, this study introduces introduce the moment balance and energy conservation equation to describe the static relationship between driving moment, elastic moment and contact moment. Finally, simulation and experiments are carried out to verify the accuracy of the proposed model. Findings For rigid manipulators, environmental contact except for the manipulated object was usually considered as a “collision” which should be avoided. For soft manipulators, an environment is an important tool for achieving manipulation goals and it might even be considered to be a part of the soft manipulator’s end-effector in some specified situations. Research limitations/implications There are also some limitations to the presented study. Although this paper has made progress in the static modeling under environmental contact, some practical factors still limit the further application of the model, such as the detection accuracy of the environment location and the deformation of the contact surface. Originality/value Based on the proposed kinematic model, the bending deformation with environmental contact is discussed in simulations and has been experimentally verified. The comparison results show the correctness and accuracy of the presented SCC model, which can be applied to predict the slender deformation under environmental contact without knowing the contact force.

Mathematical Modelling of Thermo-Hydro-Mechanical Behaviour for Concrete under Elevated Temperature

2014 ◽  
Vol 670-671 ◽  
pp. 355-364
Author(s):  
Shao Bo Zhang ◽  
Xiao Chun Wang ◽  
Xin Pu Shen
Keyword(s):  
Elevated Temperature ◽  
Stokes Equations ◽  
Constitutive Relations ◽  
Gaseous Mixture ◽  
Mass Conservation ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Energy Conservation Equation

A hydro-thermo-mechanical model was presented for concrete at elevated temperature. Three phases of continuum were adopted in this model: gaseous mixture of water vapor and dry air, liquid water, and solid skeleton of concrete. Mass conservation equations, linear momentum conservation equation, and energy conservation equation were derived on the basis of the macroscopic Navier-Stokes equations for a general continuum, along with assumptions made for the purpose of simplification. Mathematical relationships between selected primary variables and secondary variables were given with existing data from references. Specifications of the constitutive relations were made for the kinetic variables and their conjugate forces.

Effects of Non-Linearity of the Momentum Conservation Equation During Electrokinetic Transport in Nano and Microchannels

2010 ◽  
Author(s):  
Subir Bhattacharjee ◽  
Noor Al Quddus
Keyword(s):  
Porous Media ◽  
Electric Fields ◽  
Stokes Equations ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Small Scale ◽  
Electrokinetic Transport ◽  
Electrokinetic Flow ◽  
Non Linear ◽  
Momentum Conservation Equation

Electrokinetic transport phenomena, such as electroosmosis, streaming potential, electrophoresis, and sedimentation potential, are central to many micro- and nano-channel flows. During continuum modeling of such phenomena, incorporation of the electrical body force term can make the fluid momentum conservation equation highly non-linear. This non-linearity is often ignored in small-scale electrokinetic flow modeling because of our implicit reliance on the linearity of the Stokes equations for low Reynolds number flows. In this paper, ramifications of this non-linear Stokes equation in electrokinetic flows will be described with examples of our recent studies on pressure driven flows through porous media for electrokinetic power generation, electroosmotic flow of charged entities in nanochannels, and flow of DNA through self-assembled porous media under pulsed electric fields.

scholarly journals Time-dependent radiation hydrodynamics on a moving mesh

2020 ◽  
Vol 493 (4) ◽  
pp. 5397-5407 ◽  
Author(s):  
Philip Chang ◽  
Shane W Davis ◽  
Yan-Fei Jiang(姜燕飞)
Keyword(s):  
Large Scale ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Time Dependent ◽  
Moving Mesh ◽  
Test Cases ◽  
Multiple Sources ◽  
Linear Waves ◽  
Implicit Solver ◽  
Coupling Time

ABSTRACT We describe the structure and implementation of a radiation hydrodynamic solver for manga, the moving-mesh hydrodynamics module of the large-scale parallel code, Charm N-body GrAvity solver (changa). We solve the equations of time-dependent radiative transfer (RT) using a reduced speed of light approximation following the algorithm of Jiang et al. By writing the RT equations as a generalized conservation equation, we solve the transport part of these equations on an unstructured Voronoi mesh. We then solve the source part of the RT equations following Jiang et al. using an implicit solver, and couple this to the hydrodynamic equations. The use of an implicit solver ensures reliable convergence and preserves the conservation properties of these equations even in situations where the source terms are stiff due to the small coupling time-scales between radiation and matter. We present the results of a limited number of test cases (energy conservation, momentum conservation, dynamic diffusion, linear waves, crossing beams, and multiple shadows) to show convergence with analytic results and numerical stability. We also show that it produces qualitatively the correct results in the presence of multiple sources in the optically thin case.

scholarly journals Flow resistance of vegetated oblique weir-like obstacles during high water stages

2014 ◽  
Vol 18 (1) ◽  
pp. 1-14 ◽  
Author(s):  
S. Ali ◽  
W. S. J. Uijttewaal
Keyword(s):  
Flow Resistance ◽  
Research Work ◽  
High Water ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Water Levels ◽  
Sudden Expansion ◽  
Form Drag ◽  
Head Losses ◽  
The One

Abstract. At high water stages, obstacles (submerged and particularly emerged vegetation) in the flood plains of a river contribute to the flow resistance and hamper the conveyance capacity. In particular the elevated vegetated parts are expected to play an important role. The objective of this research work is to determine the form drag due to vegetated oblique weir-like obstacles. Experiments have been performed to measure the energy head losses for a range of subcritical flow conditions, varying discharges and downstream water levels. The energy head loss caused by the submerged vegetated weir-like obstacle has been modeled using an expansion loss form drag model that has been derived from the one-dimensional momentum conservation equation and accounts for the energy loss associated with a deceleration of the flow downstream of a sudden expansion. The results have been compared with the experimental data and showed an overall good agreement.

Isolation Performance Evaluation of Compressor Vibration Isolating Systems Based on LMS Test. Lab Signature

2011 ◽  
Vol 130-134 ◽  
pp. 1220-1225 ◽  
Author(s):  
Li Zhang ◽  
Hao Chen ◽  
Yan Jue Gong ◽  
Hong Wu ◽  
Shuo Zhang
Keyword(s):  
Performance Evaluation ◽  
Evaluation Criteria ◽  
Maximum Velocity ◽  
Single Layer ◽  
National Standard ◽  
Vibration Velocity ◽  
Upward Trend ◽  
Refrigeration Unit ◽  
Comparison Results ◽  
Isolation Performance

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experiment of isolation performance evaluation based on LMS Test. Lab Signature software. The comparison results of four different vibration isolating systems show that the peak values of vibration velocity response in each system mainly appear at 25Hz, 50Hz, 75Hz and 100Hz, and the maximum velocity does not exceed 22mm/s which is less than the maximum allowed by the national standard[1]. And the Vibration Level Difference (VLD) is taken as evaluation criteria for isolating vibration, that of single-layer vibration isolating system is within 10-20dB, and that of double-layer vibration isolating system is within 20-35dB. Furthermore with the increase of middle-mass, the VLD has a clear upward trend.

Exact solutions of the Einstein–Maxwell equations with linear equation of state

2012 ◽  
Vol 90 (12) ◽  
pp. 1179-1183 ◽  
Author(s):  
Tooba Feroze
Keyword(s):  
Equation Of State ◽  
Linear Equation ◽  
Maxwell Equations ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Field Equations ◽  
General Linear Equation ◽  
Energy Momentum Conservation

Two new classes of solutions of the Einstein–Maxwell field equations are obtained by substituting a general linear equation of state into the energy–momentum conservation equation. We have considered static, anisotropic, and spherically symmetric charged perfect fluid distribution of matter with a particular form of gravitational potential. Expressions for the mass–radius ratio, the surface, and the central red shift horizons are given for these solutions.

The coordinated motion planning of a dual-arm space robot for target capturing

Robotica ◽  
2011 ◽  
Vol 30 (5) ◽  
pp. 755-771 ◽  
Author(s):  
Wenfu Xu ◽  
Yu Liu ◽  
Yangsheng Xu
Keyword(s):  
Center Of Mass ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Space Robot ◽  
Coordinated Motion ◽  
First Case ◽  
Solution Equation ◽  
Target Capturing ◽  
Dual Arm ◽  
Momentum Conservation Equation

SUMMARYIn this paper, autonomous motion control approaches to generate the coordinated motion of a dual-arm space robot for target capturing are presented. Two typical cases are studied: (a) The coordinated dual-arm capturing of a moving target when the base is free-floating; (b) one arm is used for target capturing, and the other for keeping the base fixed inertially. Instead of solving all the variables in a unified differential equation, the solution equation of the first case is simplified into two sub-equations and practical methods are used to solve them. Therefore, the computation loads are largely reduced, and feasible trajectories can be determined. For the second case, we propose to deal with the linear and angular momentums of the system separately. The linear momentum conservation equation is used to design the configuration and the mounted pose of a balance arm to keep the inertial position of the base's center of mass, and the angular momentum conservation equation is used to estimate the desired momentum generated by the reaction wheels for maintaining the inertial attitude of the base. Finally, two typical tasks are simulated. Simulation results verify the corresponding approaches.

scholarly journals Numerical Study of Natural Convective Heat and Mass Transfer in an Inclined Porous Media

2018 ◽  
Vol 8 (4) ◽  
pp. 3223-3227
Author(s):  
A. Latreche ◽  
M. Djezzar
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Coupled Equations ◽  
Dimensional Parameters ◽  
Finite Volume Approach

In this study, two dimensional natural convection heat and mass transfer generated in an inclined rectangular porous cavity filled with Newtonian fluid has been investigated numerically. The cavity is heated and cooled along horizontal walls while the solutal gradient is imposed horizontally. The physical model for the momentum conservation equation makes use of the Darcy model, and the set of coupled equations is solved using a finite volume approach. The successive-under-relaxation (SUR) method is used in the solution of the stream function equation. The results are presented graphically in terms of streamlines, isotherms and iso-concentrations. The heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers for various non-dimensional parameters.

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