检索结果-南通市图书馆

American Journal of Computational Mathematics 2022年第3期12卷 306-313页

作者： Prokriti Biswas Laek Sazzad Andallah Khandaker Md. Eusha-Bin-Hafiz Department of Mathematics Jahangirnagar University Dhaka Bangladesh

In this paper, we implement energy equation coupled with viscous Burgers’ equation as a mathematical model for the estimation of thermal pollution of river water. The model is a nonlinear system of partial differential equations (PDEs) that read as an initial and boundary value problem (IBVP). For the numerical solution of the IBVP, we investigate an explicit second-order Lax- Wendroff type scheme for nonlinear parabolic PDEs. We present the numerical solutions graphically as a temperature profile, which shows good qualitative agreement with natural phenomena of heat transfer. We estimate the thermal pollution of water caused by industrialization on the bank of a river.

关键词： Viscous Burgers’ equation energy equation Heat Transfer Lax-Wendroff Type Scheme Thermal Pollution

ON THE energy equation FOR A SPATIALLY DEVELOPING INSTABILITY WAVE IN THE THEORY OF HYDRODYNAMIC STABILITY

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1990年第4期6卷 303-304页

作者： Zhou Heng (Tianjin University) Tianjin University Tianjin China

In this article,it is shown that the energy equation for a spatially developing disturbance used in all the literatures dealing with the problem of hydrodynamic stability suffers from a small,but crucial error.

关键词： hydrodynamic stability energy equation spatial mode

energy equation AND SYMMETRIC INSTABILITY CRITERION

在线全文

学校读者我要写书评

暂无评论

Acta meteorologica Sinica 1993年第2期7卷 186-193页

作者：赵瑞星 Institute of Atmospheric Physics Academia Sinica

In this paper,by using generalized normal mode method the symmetric instability criterion which can be used not only in the constant parameters but also in the variable parameters was derived from the energy equation on the symmetric *** the thermal wind was in balance or quasi-balance,the criterion was consistent with that ob- tained by Emanuel with parcel method and Hoskins with normal mode *** is shown that in the generating stage of disturbance,the symmetrically instable development of disturbance is associated with the energy transformation by which the energy of the basic field is transferred into the energy of the disturbance field.

关键词： energy equation variable parameter symmetric instability criterion

Determination of ice jam thickness—A new approach

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第3期36卷 570-581页

作者： Jun Wang Lian-sheng Sang Fei-hu Song Tie-jie Cheng Jueyi Sui School of Civil and Water Engineering Hefei University of TechnologyHefei230009China School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

In winter,rivers in cold regions often experience flood disasters resulted from ice jams or ice *** of the variation of ice jam thickness and water level during an ice jammed period are not only a practical need for ice prevention to avoid disaster and plan water resource,but also essential for the development of any mathematical model for predicting the evolution of ice *** far,some equations based on the energy equation have been proposed to describe the relationship between ice jam thickness and water ***,in the derivation of these equations,the local head loss coefficient at the ice jam head and the riverbed slope factor were ***,those reported equations cannot be used to preciously describe the flow energy equation with ice jams and accurately calculate the ice jam thickness and water *** the present study,a more comprehensive theoretical model for hydraulic calculation of ice jam thickness has been derived by considering important and essential factors including riverbed slope and local head loss coefficient at the ice jam ***,based on the data collected from laboratory experiments of ice jam accumulation,the local head loss coefficient at the ice jam head has been calculated,and the empirical equation for calculating the local head loss coefficient has been established by considering flow Froude number and the ratio of ice discharge to flow *** results of this study not only provide a new reference for calculating ice jam thickness and water level,but also present a theoretical basis for accurate CFD simulation of ice jams.

关键词： energy equation ice jam thickness local head loss coefficient ice jam head riverbed slope

Simulation of Non-Isothermal Turbulent Flows Through Circular Rings of Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第3期70卷 4341-4355页

作者： Abid.A.Memon M.Asif Memon Kaleemullah Bhatti Kamsing Nonlaopon Ilyas Khan Department of Mathematics and Social Sciences Sukkur IBA UniversitySukkur65200SindhPakistan Department of Mathematics Faculty of ScienceKhon Kaen UniversityKhon Kaen40002Thailand Department of Mathematics College of Science Al-ZulfiMajmaah UniversityAl-Majmaah11952Saudi Arabia

This article is intended to examine the fluid flow patterns and heat transfer in a rectangular channel embedded with three semi-circular cylinders comprised of steel at the *** an organization is used to generate the heat exchangers with tube and shell because of the production of more turbulence due to zigzag path which is in favor of rapid heat *** of little maintenance,the heat exchanger of such type is extensively ***,we generate simulation of flow and heat transfer using nonisothermal flow interface in the Comsol multiphysics 5.4 which executes the Reynolds averaged Navier stokes equation(RANS)model of the turbulent flow together with heat *** is tested with Prandtl number(Pr=0.7)with inlet velocity magnitude in the range from 1 to 2 m/sec which generates the Reynolds number in the range of 2.2×10^(5) to 4.4×10^(5) with turbulence kinetic energy and the dissipation rate in ranges(3.75×10^(−3) to 1.5×10^(−2))and(3.73×10^(−3)−3×10^(−2))*** correlations available in the literature are used in order to check *** results are displayed through streamlines,surface plots,contour plots,isothermal lines,and *** is concluded that by retaining such an arrangement a quick distribution of the temperature over the domain can be seen and also the velocity magnitude is increasing from 333.15%to a maximum of 514%.The temperature at the middle shows the consistency in value but declines immediately at the *** process becomes faster with the decrease in inlet velocity magnitude.

关键词： Incompressible turbulent flow heat transfer non-isothermal finite element method energy equation

Density enhancement mechanism of upwind schemes for low Mach number flows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第3期34卷 431-445页

作者： Bo-Xi Lin Chao Yan Shu-Sheng Chen School of Aeronautic Science and Engineering Beihang University

Many all-speed Roe schemes have been proposed to improve performance in terms of low speeds. Among them, the F-Roe and T-D-Roe schemes have been found to get incorrect density fluctuation in low Mach flows, which is expected to be with the square of Mach number. Asymptotic analysis presents the mechanism of how the density fluctuation problem relates to the incorrect order of terms in the energy equation paU△U. It is known that changing the upwind scheme coefficients of the pressure-difference dissipation term DP and the velocity-difference dissipation term in the momentum equation DPU to the order of O （c- 1） and O（c0） can improve the level of pressure and velocity accuracy at low speeds. This paper shows that corresponding changes in energy equation can also improve the density accuracy in low speeds. We apply this modification to a recently proposed scheme, TV-MAS, to get a new scheme, TV-MAS2. Unsteady Gresho vortex flow, double shear-layer flow, low Mach number flows over the inviscid cylinder, and NACA0012 airfoil show that energy equation modification in these schemes can obtain the expected square Ma scaling of density fluctuations, which is in good agreement with corresponding asymptotic analysis. Therefore, this density correction is expected to be widely implemented into allspeed compressible flow solvers.

关键词： energy equation Density fluctuation Roe TV-MAS Low speeds All speeds Computational fluid dynamics

Theoretical analysis and numerical simulation of mechanical energy loss and wall resistance of steady open channel flow

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2016年第3期28卷 489-496页

作者：刘士和薛娇 School of Water Resources and Hydropower Engineering Wuhan University

The mechanical energy loss and the wall resistance are very important in practical engineering. These problems are investigated through theoretical analysis and numerical simulation in this paper, The results are as follows. （1） A new mechanical energy equation for the total flow is obtained, and a general formula for the calculation of the mechanical energy loss is proposed. （2） The general relationship between the wall resistance and the mechanical energy loss for the steady channel flow is obtained, the simplified form of which for the steady uniform channel flow is in consistent with the formula used in Hydraulics deduced by 7r theorem and dimensional analysis. （3） The steady channel flow over a backward facing step with a small expansion ratio is numerica- lly simulated, and the mechanical energy loss, the wall resistance as well as the relationship between the wall resistance and the mechanical energy loss are calculated and analyzed.

关键词： channel flow energy equation mechanical energy loss resistance

A high precision computing method for heat transfer in the process of oil-water displacement

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2021年第5期33卷 958-969页

作者： Pan-pan Han Ke Chen Dong-xi Liu Yun-xiang You Jin Wang State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Yazhou Bay Institute of Deepsea Technology Shanghai Jiao Tong UniversitySanya 572000China College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 201306China COTEC Offshore Engineering Solutions Beijing 100011China

The process of oil-water displacement is one of the key technologies in offshore underwater *** hot oil is contacting the normal-temperature water,the interfacial heat transfer should be investigated as the heat loss may result in wax precipitation and solidification which will reduce the flowing of oil and thus affect the *** for the numerical simulation of heat transfer,the calculation is costly as the underwater tank is usually large and the displacement period is long.A high precision computing method would greatly reduce the mesh ***,this research is performed to establish a high precision computing *** on volume of fluid(VOF),a new form of energy equation is *** equation is derived from temperature equation and the variable internal energy per volume is *** variable is additive and has a close relationship with volume *** algorithm implantation to OpenFOAM,two non-isothermal VOF solvers are established corresponding to temperature equation and the new equation *** an analytical solution is built,the two solvers are *** solver based on the new equation presents far more accurate results than the solver based on temperature *** energy weighted scheme is more reasonable than a linear temperature distribution for the mixture phase.

关键词： Multi-phase flow energy equation heat transfer oil-water displacement volume of fluid(VOF)

The calculation of mechanical energy loss for incompressible steady pipe flow of homogeneous fluid

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2013年第6期25卷 912-918页

作者：刘士和薛娇范敏 State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

The calculation of the mechanical energy loss is one of the fundamental problems in the field of Hydraulics and Engineering Fluid Mechanics. However, for a non-uniform flow the relation between the mechanical energy loss in a volume of fluid and the kinematical and dynamical characteristics of the flow field is not clearly established. In this paper a new mechanical energy equation for the incompressible steady non-uniform pipe flow of homogeneous fluid is derived, which includes the variation of the mean turbulent kinetic energy, and the formula for the calculation of the mechanical energy transformation loss for the non-uniform flow between two cross sections is obtained based on this equation. This formula can be simplified to the Darcy-Weisbach formula for the uniform flow as widely used in Hydraulics. Furthermore, the contributions of the mechanical energy loss relative to the time averaged velocity gradient and the dissipation of the turbulent kinetic energy in the turbulent uniform pipe flow are discussed, and the contributions of the mechanical energy loss in the viscous sublayer, the buffer layer and the region above the buffer layer for the turbulent uniform flow are also analyzed.

关键词： mechanical energy loss energy equation pipe flow

Finite Dimensional Behavior for Forced Nonlinear Sobolev-Galpern equations

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2004年第2期20卷 247-256页

作者： Ya-dongShang Bo-lingGuo DepartmentofMathematics GuangzhouUniversityGuangzhou510405China InstituteofAppliedPhysicsandComputationalMathematics P.O.Box8009Beijing100088China

This paper deals with the asymptotic behavior of solutions for the nonlinear *** first show the existence of the global weak attractor in H^2(Ω)∩H_0~1(Ω) for the *** by an energy equation we prove that the global w... 详细信息

关键词： Nonlinear Sobolev-Galpern equations asymptotic behavior global attractor energy equation weak continuity