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Influence of velocity profile on calibration function of Lorentz force flowmeter

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Applied Mathematics and Mechanics(English Edition) 2014年第8期35卷 993-1004页

作者： C.STELIAN 于洋李本文 A.THESS Institute of Thermodynamics and Fluid Mechanics Ilmenau University of TechnologyIlmenau 98684Germany Department of Physics West University of TimisoaraTimisoara 300233Romania Key Laboratory of Electromagnetic Processing of Materials Northeastern University Institute of Engineering Thermodynamics German Aerospace CenterStuttgart 70569Germany

A Lorentz force flowmeter is a noncontact electromagnetic flow-measuring device based on exposing a flowing electrically conducting liquid to a magnetic field and measuring the force acting on the magnet system. The measured Lorentz force is proportional to the flow rate via a calibration coefficient which depends on the velocity distribution and magnetic field in liquid. In this paper, the influence of different velocity profiles on the calibration coefficient is investigated by using numerical simulations. The Lorentz forces are computed for laminar flows in closed and open rectangular channels, and the results are compared with the simplified case of a solid conductor moving at a constant velocity. The numerical computations demonstrate that calibration coefficients for solid bodies are always higher than for liquid metals. Moreover, it can be found that for some parameters the solid-body calibration coefficient is almost twice as high as for a liquid metal. These differences are explained by analyzing the patterns of the induced eddy currents and the spatial distributions of the Lorentz force density. The result provides a first step for evaluating the influence of the laminar velocity profiles on the calibration function of a Lorentz force flowmeter.

关键词： laminar flow numerical simulation electromagnetic velocimetry

Drag reduction in ultrahydrophobic channels with micro-nano structured surfaces

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1298-1305页

作者： LU Si YAO ZhaoHui HAO PengFei FU ChengSong School of Aerospace Tsinghua UniversityBeijing 100084China

A series of experiments have been performed to demonstrate the significant drag reduction of the laminar flow in the ultrahydrophobic channels with dual-scale micro-nano structured ***,in previous experiments,the ultrahydrophobic surfaces were fabricated with micro-structures or nano-structures and the channels were on the *** the drag reduction in macro-scale channels few reports are *** a new method was developed to fabricate ultrahydrophobic surfaces with micro-nano hierarchical structures made from carbon *** drag reductions up to 36.3% were observed in the macro-channels with ultrahydrophobic *** micro-PIV was used to measure the flow velocity in *** with the traditional no-slip theory at walls,a significant slip velocity was observed on the ultrahydrophobic surfaces.

关键词： ultrahydrophobic surfaces hierarchical structure laminar flow drag reduction velocity slip

EVALUATION　OF　HFAM　ON　A　flow　OVER　A　BACKWARD－FACING　STEP

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Journal of Hydrodynamics 1996年第3期8卷 25-30页

作者： Zhang Xiao-yuan Li Wei (Department of River Engineering, Wuhan University of Hydraulic & Electric Power Engineering, Wuhan, 430072,, P. R. China) Wuhan Univ of Hydraulic & Electric Power Engineering Wuhan China

A numerical solution for steady incompressible fluid flow over a two-dimensional backward-facing step for laminar condition was developed using a Hybrid Finite Analysis Method (HFAM). Attention is focused on obtaining accurate solution. The result of HFAM on the above problem is compared with other numerical solutions and experimental data to evaluate its numerical accuracy. It is concluded that some of the serious discrepancies that have occurred between prediction and observation at a large Reynolds number condition, and attributed in earlier studies to the inadequacy of two-dimensional model, had been due to the inaccuracy of the solution.

关键词： hybrid finite analysis method Navier-stokes laminar flow backwardfacing step.

Oscillatory flow of second grade fluid in cylindrical tube

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Applied Mathematics and Mechanics(English Edition) 2013年第9期34卷 1097-1106页

作者： A.ALI S.ASGHAR H.H.ALSULAMI Laboratoire Jean Alexandre Dieudonne Universite de Nice Sophia Antipolis Department of Mathematics Commission on Science and Technology for Sustainable Development in the SouthInstitute of Information Technology Department of Mathematics King Abdulaziz University

The unsteady oscillatory flow of an incompressible second grade fluid in a cylindrical tube with large wall suction is studied analytically. flow in the tube is due to uniform suction at the permeable walls, and the oscillations in the velocity field are due to small amplitude time harmonic pressure waves. The physical quantities of interest are the velocity field, the amplitude of oscillation, and the penetration depth of the oscillatory wave. The analytical solution of the governing boundary value problem is obtained, and the effects of second grade fluid parameters are analyzed and discussed.

关键词： second grade fluid cylindrical coordinate oscillatory flow incompressible flow laminar flow Navier-Stokes equation partial differential equation Wentzel- Kramers-Brillouin (WKB) approximation

NUMERICAL flow VISUALIZATION OF A MIXING LAYER

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Journal of Hydrodynamics 1998年第4期10卷 45-53页

作者： Lin, Jianzhong Yu, Zhaosheng Shao, Xueming Zhejiang Univ Hangzhou China

Kelvin-Helmhotz roll up of the 3-D time-developing mixing was simulated numerically. The dye lines or fluid interfaces were presented by computing a passive scalar at high Peclet number. The hydric bubbles were also simulated numerically. To help understanding the visualization results, the behaviour of coherent structures were analyzed. A comparison between vortical structure and passive scalar contours indicates that the wrapping by the vortices largely dominates the evolution of passive scalar.

关键词： Bubbles (in fluids) Computer applications flow of water Hydrodynamics laminar flow Turbulent flow

Study on the System for Separating Sulfurfrom Flue Gas and Dust

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Journal of Systems Engineering and Electronics 2000年第4期11卷 73-79页

作者： Guo Jinji Zhan Sheng Chen Hai Xie Xushi Dept. of Applied Mechanics and Engineering Zhongshan UniversityGuangzhou 510275 P. R. China

This paper describes the structure of the system for separating sulfur from flue gas and dust. In the paper, the velocities of turbulent flow and laminar flow inside the tower, the total of liquid membrance, and the additional flow of rotation fogged fluid are calculated, and the separation of rotation air-solid affected by tower is analyzed. The velocity distribution in quasi free vortex area is obtained from experiment. The minimum separated particle diameter is computed. The paper also studies the chemical reactions of flue gas containing sulfide with the dynamic fogged sulfur separating agent and discusses the main factors related to the effect of separating sulfur and dust. At last, the applications of separating sulfur in industrial stove and collecting dust in environmental engineering are introduced.

关键词： Dust Flue gases laminar flow Liquid membranes Particle size analysis Separation Turbulent flow

NUMERICAL ANALYSIS OF flowS OVER A WAVY SURFACE

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Journal of Hydrodynamics 1992年第4期4卷 72-77页

作者： Hu, Minliang Wuhan Univ of Hydraulic and Electric Engineering Wuhan China

Potential and laminar flows over a wavy surface were studied in this paper. For the potential flow, theoretical analysis and FA numerical computation were adopted respectively. In the computation of the laminar flow, the body-fitted coordinate transformation were used. The results of two methods agree very well. The results show that the difference of the wall pressure distribution between potential and laminar flows is not significant, when the ratio of wave height to wave length is smaller and there are separated regions in the laminar flow field.

关键词： laminar flow Numerical analysis Potential flow Wall flow

NUMERICALLY SOLVING STRONGLY NONLINEAR PROBLEMS BY MEANS OF NO ITERATIONS

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Journal of Hydrodynamics 1998年第1期10卷 102-108页

作者： Liao, Shijun Shanghai Jiaotong Univ Shanghai China

Based on the Homotopy Analysis Method, a direct numerical method for strongly nonlinear problems was proposed. The 2-D laminar flow over semi-infinite plate was used. The method can give the accurate enough approximations of a strongly nonlinear problem by means of no iteration and can provide a family of iterative formulas with traditional approaches.

关键词： Iterative methods laminar flow Nonlinear equations Numerical methods Viscous flow

NUMERICAL SIMULATION OF 3-D CORNER flowS IN A CIRCULATING WATER CHANNEL

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Journal of Hydrodynamics 2001年第2期13卷 63-67页

作者： Huang, Y. Wang, G.Q. Tamashima, M. Shanghai Jiaotong Univ. Shanghai 200030 China

A Navier-Stokes procedure was developed based on a finite volume method to simulate corner flows in circulating water channel (CWC). The standard 2nd-order central scheme together with a deferred correction method was applied for the convective terms. All the other terms were discretized using 2nd order central differencing. The standard k-Ε model was used for the approximation of turbulent flows. First, this method used to calculate the turbulent flows in a 90° bend and the computed results are in good agreements with the experiment. This method was also employed to calculate the flows in a model CWC corner.

关键词： Computational fluid dynamics Computer simulation Finite volume method laminar flow Navier Stokes equations Three dimensional Turbulent flow