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Vol.27, No.1
Journal of Hydrodynamics
2015
CONTENTS
Review articles
Recent progress in CFD for naval architecture and ocean engineering
STERN Frederick, WANG Zhaoyuan, YANG Jianming, SADAT-HOSSEINI Hamid, MOUSAVIRAAD Maysam,
BHUSHAN Shanti, DIEZ Matteo, YOON Sung-Hwan, WU Ping-Chen, YEON Seong Mo, DOGAN Timur, KIM
Dong-Hwan, VOLPI Silvia, CONGER Michael, MICHAEL Thad, XING Tao, THODAL Robert S.,
GRENESTEDT Joachim L....................................................................................................................................(1)
Interactions between vegetation, water flow and sediment transport: A review
WANG Chao (王超), ZHENG Sha-sha (郑莎莎), WANG Pei-fang (王沛芳), HOU Jun (侯俊)...................(24)
Articles
Extreme wave loads on submerged water intakes in shallow water
CORNETT Andrew, HECIMOVICH Mark, NISTOR Ioan..................................................................................(38)
Numerical simulation of thermal convection of viscoelastic fluids in an open-top porous medium with constant
heat flux
NIU Jun (牛骏), SHI Zai-hong (石在虹), TAN Wen-chang (谭文长).......................................................(52)
Improvement of numerical simulation of bimolecular reactive transport using time-dependent parameters
LIU Yong (刘咏), QIAN Jia-zhong (钱家忠), MA Lei (马雷), ZHAO Wei-dong (赵卫东),
LUO Qian-kun (骆乾坤).....................................................................................................................................(62)
Numerical simulation of rotating arm test for prediction of submarine rotary derivatives
PAN Yu-cun (潘雨村), ZHOU Qi-dou (周其斗), ZHANG Huai-xin (张怀新)................................................(68)
Flow and heat transfer characteristics around egg-shaped tube
ZHANG Guan-min (张冠敏), LENG Xue-li (冷学礼), ZHOU Nai-xiang (周乃香), SHI Yan-ping (师艳平),
LI Li-min (李利民).............................................................................................................................................(76)
Modelling of solute transport in a filled fracture: Effects of heterogeneity of filled medium
DOU Zhi (窦智), ZHOU Zhi-fang (周志芳).....................................................................................................(85)
Penetration efficiency of nanoparticles in a bend of circular cross-section
YIN Zhao-qin (尹招琴), LIN Jian-zhong (林建忠), LOU Ming (娄明)...........................................................(93)
Application of support vector machine in drag reduction effect prediction of nanoparticles adsorption method on
oil reservoir’s micro-channels
DI Qin-feng (狄勤丰), HUA Shuai (华帅), DING Wei-peng (丁伟朋), GONG Wei (龚伟),
CHENG Yi-chong (程毅翀), Ye Feng (叶峰) ...................................................................................................(99)
Numerical research on the performances of slot hydrofoil
WEI Qun (魏群), CHEN Hong-xun (陈红勋), ZHANG Rui (张睿)............................................................(105)
Numerical simulation of 3-D water collapse with an obstacle by FEM-level set method
WANG Ji-fei (王吉飞), WAN De-cheng (万德成)..........................................................................................(112)
3-D numerical investigation of the wall-bounded concentric annulus flow around a cylindrical body with a
special array of cylinders
ZHANG Xue-lan (张雪兰), SUN Xi-huan (孙西欢), LI Yong-ye (李永业).................................................(120)
Wave-current impacts on surface-piercing structure based on a fully nonlinear numerical tank
LI Yong (李勇), LIN Mian (林缅)...................................................................................................................(131)
Study of errors in ultrasonic heat meter measurements caused by impurities of water based on ultrasonic
attenuation
SHI Shuo (石硕), LIU Zheng-gang (刘正刚), SUN Jian-ting (孙建亭), ZHANG Min (张敏),
DU Guang-sheng (杜广生), LI Dong (李冬)..................................................................................................(141)
Ferrofluid measurements of bottom velocities and shear stresses
MUSUMECI Rosaria E., MARLETTA Vincenzo, ANDÒ Bruno, BAGLIO Salvatore, FOTI Enrico..............(150)
Letter
Flow choking characteristics of slit-type energy dissipaters
WU Jian-hua (吴建华), WAN Bin (万彬), MA Fei (马飞), LI Tong-chun (李同春)...................................(159)
Serial parameters: CN31-1563*1989*b*A4*162*en*P*￥30.00*1000*17*2015-02
Recent progress in CFD for naval architecture and ocean engineering*
STERN Frederick1, WANG Zhaoyuan1, YANG Jianming1, SADAT-HOSSEINI Hamid1, MOUSAVIRAAD
Maysam1, BHUSHAN Shanti2, DIEZ Matteo3, YOON Sung-Hwan1, WU Ping-Chen1, YEON Seong Mo1,
DOGAN Timur1, KIM Dong-Hwan1, VOLPI Silvia1, CONGER Michael1, MICHAEL Thad1, XING Tao4,
THODAL Robert S.5, GRENESTEDT Joachim L.5
1. IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA, USA,
E-mail: [email protected]
2. Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS 39759, USA
3. CNR-INSEAN, Rome, Italy
4. Department of Mechanical Engineering, University of Idaho, Idaho 83844-0902, USA
5. Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, 18015, USA
(Received January 1, 2015, Revised January 14, 2015)
Abstract: An overview is provided of CFDShip-Iowa modeling, numerical methods and high performance computing (HPC),
including both current V4.5 and V5.5 and next generation V6. Examples for naval architecture highlight capability and needs. High
fidelity V6 simulations for ocean engineering and fundamental physics describe increased resolution for analysis of physics of fluids.
Uncertainty quantification research is overviewed as the first step towards development stochastic optimization.
Key words: CFD, naval architecture, ocean engineering
Interactions between vegetation, water flow and sediment transport: A review*
WANG Chao (王超), ZHENG Sha-sha (郑莎莎), WANG Pei-fang (王沛芳), HOU Jun (侯俊)
Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes, Ministry of Education,
College of Environment, Hohai University, Nanjing 210098, China, E-mail: [email protected]
(Received May 28, 2014, Revised January 6, 2015)
Abstract: The vegetation, as one of the most important components, plays a key role in the aquatic environment. This paper reviews
recent progress on the complex interaction between the vegetation and the water flow. Meanwhile, the relationships between the
vegetation and the sediment transport are discussed. The vegetation characteristics, such as the shape, the flexibility and the height,
have significant effects on the flow structures. The density and the arrangement of the vegetation influence the flow velocity in
varying degrees and the flow resistance increases with the increase of the plant density. In turns, the growth of aquatic plants is
influenced by the water flow via the direct effect (stretching, breakage, uprooting, etc.) and the indirect effect (changes in gas
exchange, bed material distribution, sediment resuspension etc.). Numerical models were developed and widely used for the flow
through vegetated waterways, and the results could be applied to solve engineering problems in practice. The sediment is essential
for the survival of most vegetation. The existence of the vegetation helps to resist the deformation and the erosion of the bed
sediment, to maintain the bed stability and to improve the water quality by removing suspended particles. Additionally, the effects of
the sediment transport on the growth of the vegetation mainly consist of the reduction of their photosynthetic capacity by decreasing
the water transparency and hindering the exchange of gas and nutrients between plants and water by attaching particles to plant
leaves. Therefore, the interaction between the vegetation and the sediment transport is great and complicated. In order to establish a
healthy aquatic ecosystem, it is important to study the relationships between the vegetation, the water flow and the sediment
transport.
Key words: interaction, vegetation, water flow, sediment transport
Extreme wave loads on submerged water intakes in shallow water*
CORNETT Andrew1,2, HECIMOVICH Mark2, NISTOR Ioan2
1. Ocean, Coastal and River Engineering, National Research Council, Ottawa, Canada
2. Department of Civil Engineering, University of Ottawa, Ottawa, Canada,
E-mail: [email protected]
(Received October 9, 2014, Revised November 3, 2014)
Abstract: This paper provides new guidance concerning the hydrodynamic loads on submerged intake structures located in shallow
water under breaking and non-breaking waves. Results from a series of experiments conducted in a large wave flume at 1:15 scale to
study the hydrodynamic forces exerted on a generic intake structure located on a sloping seabed in shallow water below breaking and
non-breaking irregular waves are presented. Based on analysis of the experimental data, empirical relationships are developed to
describe the peak loads in terms of characteristic wave parameters such as significant wave height and peak wave period. The
distribution of the peak loads across different parts of the intake structure is also described. Drag and inertia force coefficients for the
horizontal forcing on the intake structure and for the main structural sub-components are derived and presented. It is shown that the
well-known Morison equation, with appropriate drag and inertia force coefficients, can provide reasonable estimates of the moderate
horizontal loads, but the peak loads are less well predicted.
Key words: wave force, water intake, drag force, inertia force, coastal engineering
Numerical simulation of thermal convection of viscoelastic fluids in an open-top
porous medium with constant heat flux*
NIU Jun (牛骏)1, SHI Zai-hong (石在虹)1, TAN Wen-chang (谭文长)2
1. Petroleum Exploration and Production Research Institute of SINOPEC, Beijing 100083, China,
E-mail: [email protected]
2. State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Aerospace
Engineering, College of Engineering, Peking University, Beijing 100871, China
(Received July 23, 2013, Revised April 8, 2014)
Abstract: This paper makes a numerical study of the buoyancy-driven convection of a viscoelastic fluid saturated in an open-top
porous square box under the constant heat flux boundary condition. The effects of the relaxation and retardation times on the onset of
the oscillatory convection, the convection heat transfer rate and the flow pattern transition are investigated. It is shown that a large
relaxation time can destabilize the fluid flow leading to an early onset of the thermal convection and a high heat transfer rate, while a
large retardation time tends to stabilize the flow and suppress the convection onset and the heat transfer. After the convection sets in,
the flow bifurcation appears earlier with the increase of the relaxation time and the decrease of the retardation time, resulting in more
complicated flow patterns in the porous medium. Furthermore, with the increase of the ratio of the relaxation time to the retardation
time, the fluid may be blocked from flowing through the open-top boundary, which may be caused by the viscoelastic effect. Finally,
the comparison of our results with those under isothermal heating boundary conditions reveals that the heat transfer rate corresponding to a constant heat flux boundary is always higher.
Key words: thermal convection, viscoelastic fluids, porous medium, constant heat flux
Improvement of numerical simulation of bimolecular reactive transport using
time-dependent parameters*
LIU Yong (刘咏)1, QIAN Jia-zhong (钱家忠)2, MA Lei (马雷)2, ZHAO Wei-dong (赵卫东)2,
LUO Qian-kun (骆乾坤)2
1. School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, China,
E-mail: [email protected]
2. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
(Received September 24, 2012, Revised January 6, 2015)
Abstract: The overestimation of the contaminant concentration is a main issue in simulating the reactive transport using the common
advection-dispersion-reaction equation (ADRE). To solve this problem, a new modeling method is developed. The parameters of the
model are identified based on experimental data. The results of the model are compared with previous results in the literature, and the
sensitivity of the model is analyzed by examining the model’s response to changes of the model parameters. Main conclusions are as
follows: (1) The numerical modeling approach is feasible with an improved simulating accuracy. The predicted values are in
agreement with the experimental measurements. The relative errors of the peak concentration between the simulated and
experimental values are less than 2.5%. The errors are greatly reduced as compared with the results (about 67.8% as the maximum)
based on a traditional ADRE in the literature. (2) There are three parameters ( m , 0 and D ) which can be calibrated on the basis
of experimental data in the model. The reactive product concentrations are mainly influenced by the parameters involved in the
reactive ratio such as m and 0 . The hydrodynamic dispersion coefficient D has almost no influence on the reactive product
transport. (3) Our model does not provide better fitting curves for the “early arrival” and the “long tail”. The “early arrival” and the
“long tail” are associated with low values of the product AB. Under these conditions, the reaction rate is close to 0, and the model of
the ADRE reduces to the advection-dispersion equation (ADE). Further mechanism study is needed in the future.
Key words: numerical simulation, bimolecular reactive transport, porous media, ADRE
Numerical simulation of rotating arm test for prediction of submarine rotary
derivatives*
PAN Yu-cun (潘雨村)1,2, ZHOU Qi-dou (周其斗)2, ZHANG Huai-xin (张怀新)1
1. State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
2. Department of Naval Architecture, Naval University of Engineering, Wuhan 430033, China,
E-mail: [email protected]
(Received June 18, 2013, Revised November 6, 2014)
Abstract: The numerical method is used for predicting the rotary-based hydrodynamic coefficients of a submarine. Unsteady RANS
simulations are carried out to numerically simulate the rotating arm test performed on the SUBOFF submarine model. The dynamic
mesh method is adopted to simulate the rotary motions. From the hydrodynamic forces and moments acting on the submarine at
different angular velocities, the rotary derivatives of the submarine can be derived. The computational results agree well with the
experimental data. The interaction between the sail tip vortex and the cross flow in the hull boundary layer is discussed, and it is
shown that the interaction leads to the “out-of-plane” loads acting on the submarine.
Key words: submarine maneuverability, hydrodynamic coefficients, rotating arm test, dynamic mesh
Flow and heat transfer characteristics around egg-shaped tube*
ZHANG Guan-min (张冠敏)1, LENG Xue-li (冷学礼)1, ZHOU Nai-xiang (周乃香)2, SHI Yan-ping (师艳平)3,
LI Li-min (李利民)3
1. School of Energy and Power Engineering, Shandong University, Jinan 250061, China,
E-mail: [email protected]
2. Shandong Urban and Rural Planning and Design Institute, Jinan 250013, China
3. Shanxi Fenxi Heavy Industry Co. Ltd. Technical Center, Taiyuan 030027, China
(Received June 22, 2013, Revised January 16, 2014)
Abstract: This paper studies the flow and heat transfer characteristics around a new type of egg-shaped tubes made up of a semicircle upstream and a semi-ellipse downstream, numerically and experimentally, for Reynolds numbers varying from 4 000 to 5 0000
based on the hydraulic diameter. These tubes have axis ratios,  = 1, 1.5, 2, 3, 4, and 5 with the major axis parallel to the mainstream. When  = 1 , the tube is a circular one and when 1/  = 0 , it is a flat plate. Numerical results show that the minimum value
of C p occurs at an angular position, which decreases as  decreases, and the maximum value of C f gradually increases with
the increase of  . Simulated results agree very well with those available in the existing literature. The egg-shaped tube has a higher
favorable pressure gradient at its front and a lower adverse pressure gradient at its back, that helps the flow delay a separation from
the tubes’ surface. Empirical correlations for each tube are obtained by numerical simulations relating the dimensionless heat transfer
coefficient with the Reynolds Number and the Prandtl Number. The performance evaluation criterion (PEC) is used to analyze the
level of the heat transfer enhancement for egg-shaped tubes. It is found that an egg-shaped tube with  = 2 has the best overall heat
transfer performance when Re  11952 .
Key words: heat transfer enhancement, egg-shaped tube, numerical simulation, flow resistance
Modelling of solute transport in a filled fracture: Effects of heterogeneity of
filled medium*
DOU Zhi (窦智), ZHOU Zhi-fang (周志芳)
School of Earth Sciences and Engineering, Hohai University, Nanjing 210098, E-mail: [email protected]
(Received June 22, 2013, Revised October 23, 2013)
Abstract: In this paper, the developed lattice Boltzmann method (LBM) is used to model the solute transport in a filled fracture
under a heterogeneous advective velocity field. The results of the developed LBM in modelling the solute transport are compared
with the published experimental data. The numerically derived BTCs indicate that the distribution of the filled medium in the fracture
has a significant effect on the characteristics of the BTCs, even with the same porosity. The heterogeneity of the filled medium is
responsible not only for the heterogeneous advective velocity field but also for the early arrival and long tails of the BTCs. The long
tailings of the BTCs increase their length with the increase of the duration of the input pulse. Furthermore, the BTCs obtained from
the LBM simulations are well consistent with the two-region model (TRM). The fitting results show that the fractional mobile region
varies with the distribution of the filled medium. The long tailings of the BTCs increase their length with the increase of the
immobile region while the concentration peak value increases with the increase of the mobile region.
Key words: solute transport, heterogeneity, lattice Boltzmann method, two-region model, fracture
Penetration efficiency of nanoparticles in a bend of circular cross-section*
YIN Zhao-qin (尹招琴), LIN Jian-zhong (林建忠), LOU Ming (娄明)
Institute of Fluid Measurement and Simulation, China Jiliang University, Hangzhou 310018, China,
E-mail: [email protected]
(Received June 23, 2013, Revised August 27, 2013)
Abstract: In order to quantify the losses of nanoparticles in a bend of circular cross-section, the penetration efficiency of nanoparticles of sizes ranging from 5.6 nm to 560 nm in diameter is determined as a function of the Dean number, the Schmidt number and the
bend angle. It is shown that the effect of the Dean number on the penetration efficiency depends on the particle size. The Dean
number has a stronger effect on the penetration efficiency for small particles than for large particles. There exists a critical value of
the Dean number beyond which the penetration efficiency turns from increasing to decreasing with the increase of the Dean number,
and this critical value is dependent on the particle size and the bend length. The penetration efficiency increases abruptly when the
Schmidt number changes from 7 500 to 25 000. Finally, a theoretical relation between the penetration efficiency and the Dean
number, the Schmidt number and the bend length is derived.
Key words: nanoparticle, penetration efficiency, bends, measurement, Dean number, Schmidt number
Application of support vector machine in drag reduction effect prediction of
nanoparticles adsorption method on oil reservoir’s micro-channels*
DI Qin-feng (狄勤丰)1,2, HUA Shuai (华帅)1,2, DING Wei-peng (丁伟朋)1, GONG Wei (龚伟)2, CHENG
Yi-chong (程毅翀)1,2, Ye Feng (叶峰)1,2
1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China
2. Shanghai Key Laboratory of Mechanics in Energy and Environment Engineering, Shanghai 200072, China,
E-mail: [email protected]
(Received August 29, 2013, Revised November 27, 2013)
Abstract: Due to the complexity of influence factors in the nanoparticles adsorption method and the limitation of data samples, the
support vector machine (SVM) was used in the prediction method for the drag reduction effect. The basic concept of SVM was
introduced, and the  - SVR programming for the kernel function on the radial basis was established firstly with the help of the
MATLAB software. Then, an analysis was made for the influencing factors of the drag reduction effect in nanoparticles adsorption.
Finally, a prediction model for the drag reduction effect of nanoparticles was established, and the accuracy of training sample and
prediction sample was analyzed. The result shows that the SVM has good availability and can be used as a rapid evaluation method
of the drag reduction effect prediction of nanoparticles adsorption method.
Key words: nanoparticles adsorption method, support vector machine (SVM), prediction model, rapid evaluation, enhanced oil
recovery
Numerical research on the performances of slot hydrofoil*
WEI Qun (魏群)1,2, CHEN Hong-xun (陈红勋)1, ZHANG Rui (张睿)1
1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China
2. Institute of Civil Engineering, Nanchang University, Nanchang 330031, China, E-mail: [email protected]
(Received December 21, 2013, Revised July 3, 2014)
Abstract: The paper presents an numerical study of the hydraulic and cavitating characteristics of a slot hydrofoil at the angle of
incidence of 6o . Results indicate that the performance of this slot hydrofoil is better than the original hydrofoil at non-cavitation
condition, but deteriorates sharply once cavitation occurred. To improve the performance, a new splitting scheme was put forward
and optimization research was carried out at the same indicent angle, numerical results show that the optimized slot hydrofoil achieves better hydraulic and cavitation performances.
Key words: hydrofoil, performance, optimal design, cavitation inhibition
Numerical simulation of 3-D water collapse with an obstacle by FEM-level set
method*
WANG Ji-fei (王吉飞)1,2, WAN De-cheng (万德成)1,2
1. State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai 200240, China
2. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai 200240, China,
E-mail: [email protected]
(Received January 6, 2014, Revised March 20, 2014)
Abstract: An interface capturing approach based on a level set function for simulating transient two-phase viscous incompressible
flows is applied in this paper. A narrow-band signed distance function is adopted to indicate the phase fields and the interface. The
multiphase flow is numerically solved by three stages with finite element method (FEM): (1) solving a two-fluid Navier-Stokes (N-S)
equations over the whole domain, (2) transporting the level set function with the obtained velocity field, (3) the level set function
correction through a renormalization with continuous penalization which preserves the thickness of the interface. In this paper, the
3-D water column collapse with an obstacle is simulated, which yielded good agreement with the experimental data.
Key words: 3-D water collapse with an obstacle, free surface, interface capturing, level set method, finite element method
3-D numerical investigation of the wall-bounded concentric annulus flow around
a cylindrical body with a special array of cylinders*
ZHANG Xue-lan (张雪兰)1, SUN Xi-huan (孙西欢)1,2, LI Yong-ye (李永业)1
1. College of Water Resource and Engineering, Taiyuan University of Technology, Taiyuan 030024, China,
E-mail: [email protected]
2. Shanxi Conservancy Technical College, Yuncheng 044004, China
(Received March 31, 2014, Revised June 3, 2014)
Abstract: Concentric annulus flow around a combinational cylindrical body with a special array of cylinders at five high Reynolds
numbers is investigated numerically using Fluent 6.3.26 in this paper. The numerical results show a good agreement with the
experimental data in regard to the axial velocity of the flow. This study focuses on the flow structure and the hydrodynamic
characteristics based on the velocity distribution, the pressure distribution, streamlines and vectors under 1-D, 2-D and 3-D conditions. Meanwhile, some global parameters including the pressure coefficient, the drag coefficient and the lift coefficient are analyzed.
Numerical results show that the high velocity region and the reverse wake zone with low velocity exist in some spaces due to the
disturbance of the cylindrical body. Negative pressures appear in some regions. Neither a wide area vortex nor the vortex shedding
appears in the wall-bounded domain. The drag along the axial direction is the main force acting on the cylindrical body in the pipe
domain. The annulus flow around the cylindrical body is analyzed to reveal the hydrodynamic characteristics of the complex turbulent concentric annulus flow field due to the multi-effects in the pipeline.
Key words: numerical simulation, concentric annulus, high Reynolds number, cylindrical body, hydrodynamic characteristics
Wave-current impacts on surface-piercing structure based on a fully nonlinear
numerical tank*
LI Yong (李勇), LIN Mian (林缅)
Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China, E-mail: [email protected]
(Received September 5, 2014, Revised October 24, 2014)
Abstract: Fully nonlinear wave-body interactions for a surface-piercing structure with combined wave-current flow in different
water depths are studied by using a 2-D numerical tank. The model is based on Reynolds averaged Navier-Stokes (RANS) equations
and renormalization group (RNG) k -  model. The mean and maximum wave-current impacts, including forces in two directions
and rotational moment, are calculated and discussed. The effects of U / C and water depth condition on forces and moment have
been investigated and the results for combined irregular waves and currents are compared with those induced by combined regular
waves and currents.
Key words: numerical wave-current tank, wave-current impacts, surface-piercing structure, irregular wave, wave spectrum
Study of errors in ultrasonic heat meter measurements caused by impurities of
water based on ultrasonic attenuation*
SHI Shuo (石硕)1,2, LIU Zheng-gang (刘正刚)1, SUN Jian-ting (孙建亭)1, ZHANG Min (张敏)1,
DU Guang-sheng (杜广生)1, LI Dong (李冬)1
1. School of Energy and Power Engineering, Shandong University, Jinan 250061, China
2. Key Laboratory of Renewable Energy Utilization Technology of National Education Ministry, Shandong
Jianzhu University, Jinan 250001, E-mail: [email protected]
(Received September 28, 2014, Revised December 16, 2014)
Abstract: Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects
of different impurity species and concentrations on the accuracy of heat meters, flow tests were carried out for the suspending of
calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity
concentrations and species, the influence of the impurities on the heat meter measurement accuracy is evaluated. In order to avoid the
inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface.
According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the heat meter accuracy
severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the heat
meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the heat
meter measurement accuracy when the water contains impurities.
Key words: impurities, ultrasonic heat meter, amplitude attenuation, measuring error, experiment study
Ferrofluid measurements of bottom velocities and shear stresses*
MUSUMECI Rosaria E.1, MARLETTA Vincenzo2, ANDÒ Bruno2, BAGLIO Salvatore2, FOTI Enrico1
1. Department of Civil Engineering and Architecture, University of Catania, Catania, Italy,
E-mail: [email protected]
2. Department of Electric, Electronic and Computer Science Engineering, University of Catania, Catania, Italy
(Received October 9, 2014, Revised November 3, 2014)
Abstract: A novel direct measurement strategy of bottom velocities and shear stresses based on the use of ferrofluids is presented.
Such a strategy overcomes some of the limits of state-of-the-art instruments. A preliminary experimental campaign has been carried out
in the presence of currents in steady flow conditions in order to test the effects of ferrofluid quantity and of the controlling permanent
magnetic force. An alternating current (AC) circuit and a direct current (DC) conditioning circuit have been tested. For velocities larger
than 0.05 m/s, the near-bottom velocity-output voltage calibration curve has a monotone parabolic shape. The sensitivity of the
instrument is increased by a factor of 30 when the DC circuit is used.
Key words: magnetofluids, Rosensweig effect, flow resistances, bed shear stresses, bottom velocities
Flow choking characteristics of slit-type energy dissipaters*
WU Jian-hua (吴建华), WAN Bin (万彬), MA Fei (马飞), LI Tong-chun (李同春)
National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, College
of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China,
E-mail: [email protected]
(Received November 25, 2014, Revised December 14, 2014)
Abstract: In this paper, the behavior of the flow choking, including the critical and developing states, was experimentally investigated by means of five slit-type outlets, characterized by the outlet width, the contraction angle and the opening of the working gate.
The results showed that the approach flow Froude number of the critical choking decreases if the outlet width increases, or the contraction angle decreases, or the opening increases. There is the hysteresis when the flow choking develops, i.e., the Froude numbers
of the appearance and disappearance of the flow choking at the increasing discharge regime are all larger than those at the decreasing
discharge regime. For various widths of the outlets, the differences between the critical Froude numbers at small opening are much
larger than thoset at large opening. The change range from appearance to disappearance of the flow choking at small opening is
smaller than that at large opening.
Key words: flow choking, slit-type energy dissipater, partial opening, Froude number