Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
47
1
2020
TISSUE BLOOD PERFUSION INVERSE ANALYSIS: TEMPERATURE VS. HEAT FLUX APPROACH
1-21
10.1615/InterJFluidMechRes.2019025020
Jurij
Iljaž
Faculty of Mechanical Engineering, University of Maribor, Smetanova ulica 17, SI-2000
Maribor, Slovenia
Leopold
Škerget
University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor,
Slovenia
Jure
Marn
Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia
bio-heat
boundary element method
Levenberg-Marquardt optimization
space-dependent perfusion
non-homogeneous tissue
The goal of this study is prediction of blood perfusion through non-homogeneous tissue based on available data of either skin temperature (Dirichlet) or heat flux (Neumann) boundary conditions, and predicting the other. A method proposed for comparing both approaches by solving inverse bio-heat problems is the Boundary Element Method employing Levenberg-Marquardt optimization combined with first-order Tikhonov regularization process and the L-Curve method to determine the optimal value of regularization parameter. Both proposed approaches, Dirichlet and Neumann, have advantages and disadvantages. Our hypothesis was tested by comparing solutions to existing available results as well as to our own results considering different measurement noise levels. The greatest difference between both approaches proposed is the case of low measurement noise where the latter gives better agreement with data, especially for the deep tissue region. The limitation of the proposed method was found to be in the case of high measurement noise where solution was comparable to available measured data in the region close to the boundary. This work should contribute to better understanding of diagnostics of blood perfusion taking advantage of fast measurements of skin temperature and heat flux to determine blood perfusion.
NUMERICAL ANALYSIS OF FLUID FLOW AND HEAT TRANSFER CHARACTERISTICS OF A NEW KIND OF VORTEX GENERATORS BY COMPARISON WITH THOSE OF TRADITIONAL VORTEX GENERATORS
23-42
10.1615/InterJFluidMechRes.2019026753
Younes
Menni
Unite of Research on Materials and Renewable Energies - URMER - Department of Physics,
Faculty of Sciences, Abou Bekr Belkaid University, BP 119-13000-Tlemcen, Algeria
Ali J.
Chamkha
Faculty of Engineering, Kuwait College of Science and Technology, Doha District, Kuwait;
Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200,
Jeddah 21589, Saudi Arabia; Mechanical Engineering Department, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Saudi Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, P.O. Box
10021, Ras Al Khaimah, United Arab Emirates
Ahmed
Azzi
Unit of Research on Materials and Renewable Energies – URMER, Abou Bekr Belkaid
University, BP 119-13000-Tlemcen, Algeria; Department of Mechanical Engineering, Faculty of Technology, Abou Bekr Belkaid University,
BP 230-13000-Tlemcen, Algeria
Chafika
Zidani
Unit of Research on Materials and Renewable Energies, URMER, Physics Department Faculty
of Sciences, Abou Bekr Belkaïd University, BP 119-13000-Tlemcen, Algeria
simulation
heat transfer
fluid flow
turbulent regime
v-baffle
finite volume
A fluid flow and thermal transfer analysis in the presence of baffles was reported. Two various geometries of baffles, i.e., flat rectangular and V-upstream, arranged in overlapping in a two-dimensional horizontal channel of rectangular cross section were simulated in this paper. The governing equations, i.e., continuity, x-momentum, y-momentum, energy, turbulent energy, and turbulent dissipation rate, were discretized by the finite volume method and the SIMPLE algorithm was implemented. Effects of the V-shaped baffle angle (θ) were simulated to find the optimum thermal performance for the Reynolds number from 12,000 to 32,000. Four flow attack values are taken for the θ and which are 45°, 50°, 55°, and 60°, respectively. The impact of the V-baffle geometry on the heat transfer enhancement and fluid flow characteristics was illustrated and this is comparing the data of this configuration with those of the simple baffle.
NUMERICAL INVESTIGATION OF FLOW ON A DARRIEUS VERTICAL AXIS WIND TURBINE BLADE WITH VORTEX GENERATORS
43-58
10.1615/InterJFluidMechRes.2020026791
A.
Dadamoussa
Laboratoire d'Aéronautique et Systèmes Propulsifs, Départment de Génie Mécanique,
Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf, USTO-MB, Oran,
Algérie
Khadidja
Boualem
Université de Relizane Ahmed Zabana, Algérie
Tayeb
Yahiaoui
Laboratoire d'Aéronautique et Systèmes Propulsifs, Départment de Génie Mécanique,
Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf, USTO-MB, Oran,
Algérie
Omar
Imine
Laboratory of Aeronautical Systems and Propulsion, University of Sciences and Technology–Mohamed Boudiaf–Oran BP 1505 El M’Naouer, Algeria
Darrieus
NACA 4415
vortex generator
fluid dynamics
CFD
This paper intends to improve the Darrieus wind turbine performance by using a new design of vortex generators. Computational fluid dynamics (ANSYS CFX.15) have been used to simulate the turbine in steady state and incompressible flow with Reynolds number Re = 2.05 × 105. The shear stress transport k−ω turbulence model has been used to complete the governing equations, and the vertical axis wind turbine (VAWT) has been modeled in three dimensions. The geometric parameters' (the vortex generators and their sizes with respect to the profile) influence on the performance of VAWTs is studied. The first part of this work presents the flow behavior around the smooth airfoil, for a different angle of attack, which is compared with experimental data. The second part studies the passive control effect of the vortex generators (VGs) placed first on the extrados, then on the intrados, and finally on the two sides, for different VG heights. This research indicates the VAWT's performance can be greatly improved by correctly choosing the size and position of the VG, in which the smaller height of VG increases the tangential coefficient considerably.
ESTIMATION OF PRESSURE DROP FOR NON-NEWTONIAN LIQUID FLOW THROUGH BENDS USING ADAPTIVE NON-PARAMETRIC MODEL
59-69
10.1615/InterJFluidMechRes.2019021943
Suman
Debnath
Department of Mathematics, NIT Agartala, Jirania, Agartala, Tripura West, 799046, India
Anirban
Banik
Department of Civil Engineering, NIT Agartala, Jirania, Agartala, Tripura West, 799046,
India
Tarun Kanti
Bandyopadhyay
Department of Chemical Engineering, NIT Agartala, Jirania, Agartala, Tripura West, 799046,
India
Mrinmoy
Majumder
Department of Civil Engineering, NIT Agartala, Jirania, Agartala, Tripura West, 799046,
India
Apu Kumar
Saha
Department of Mathematics, NIT Agartala, Jirania, Agartala, Tripura West, 799046, India
bends
non-Newtonian fluid
GMDH
optimization
Studies of non-Newtonian pseudo-plastic liquid flow through bends are important as it is used in many chemical process industries like petroleum and refinery, pharmaceutical, rubber, paper pulp, and food industries, as a piping component for fluid flow transfer and heat transfer equipment in boiler, heat exchanger, distillation column, and air-crafts. In the concerned study, non-Newtonian pseudo-plastic SCMC solution (sodium salt of carboxy methyl cellulose solution) liquid flow through different types of angle of 0.0127 m diameter pipe bends has been investigated experimentally to optimize the frictional pressure drop across the bends in laminar and water flow in turbulent condition. The Group Method of Data Handling (GMDH) with multilayered neural network is used to predict and minimize the pressure drop. Pressure drop is minimized at the optimal concentration of the fluid and the bend angle. The GMDH model is validated against the validation techniques like Nash−Sutcliffe efficiency (NSE), percent bias (PBIAS), RMSE-observations standard deviation ratio (RSR), etc. It has been found that software-predicted data can be used for the trouble shooting in industry and in equipment design.
THE EFFECT OF ASPECT RATIO ON HYDRAULIC AND HEAT TRANSFER CHARACTERISTICS IN A FRACTAL MICROCHANNEL
71-84
10.1615/InterJFluidMechRes.2019028306
Wen-Tao
Yan
Department of Process Equipment and Control Engineering, School of Mechanical
Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
Cong
Li
Department of Process Equipment and Control Engineering, School of Mechanical
Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
Wei-Biao
Ye
Department of Process Equipment and Control Engineering, School of Mechanical
Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
Yuxiang
Hong
Department of Chemistry and Chemical Engineering, Lishui University, Lishui 323000,
People's Republic of China
Si-Min
Huang
Key Laboratory of Distributed Energy Systems of Guangdong Province, Department of Energy
and Chemical Engineering, Dongguan University of Technology, Dongguan 523808, People's
Republic of China
aspect ratio
hydraulic and heat transfer characteristics
fractal microchannel
The effect of aspect ratio on hydraulic and heat transfer characteristics in the fractal microchannel is investigated numerically and the results are presented in this paper. In the past researches, most researchers studied the effect of channel geometry by varying the channel height for a constant channel width or varying the width for a constant height. In the present work, the effect of aspect ratio is studied by varying the channel width and depth while keeping the inlet cross-sectional area or hydraulic diameter constant. Nine microchannel heat sinks which have different aspect ratios are investigated by numerical simulation. Simulations have been conducted for various values of the inlet velocity covering 5, 6, 7, 8, and 9 m/s and aspect ratio including 1/3,1/2,1, 2, 3. The thermal and hydraulic performances of the fractal microchannels are discussed in terms of the base temperature, Nusselt number, pressure drop and thermal resistance, etc. It is indicated that the aspect ratio significantly affects the hydrodynamic and thermal characteristics of the fractal microchannel heat sink. The enhanced heat transfer is achieved by increasing the aspect ratio of the entrance. The microchannels with lower aspect ratio have bigger pressure drops. The case CCS-(1/3) has medium heat transfer performance and the worst hydraulic characteristics. The microchannel CHD-3 has a better heat transfer performance; meanwhile, it also has relatively small pressure drop.
AERODYNAMIC MODELS APPROXIMATE FOR ESTIMATING THE BLADE PERFORMANCE OF A DARRIEUS-TYPE CROSS-FLOW WATER TURBINE
85-98
10.1615/InterJFluidMechRes.2019027180
Fatima
Meddane
Laboratoire d'Aéro-Hydrodynamique Naval, Département de Génie Maritime,
Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf,
USTO-MB, Oran, Algérie
Tayeb
Yahiaoui
Laboratoire d'Aéronautique et Systèmes Propulsifs, Département de Génie Mécanique,
Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf, USTO-MB, Oran,
Algérie
Omar
Imine
Laboratory of Aeronautical Systems and Propulsion, University of Sciences and Technology–Mohamed Boudiaf–Oran BP 1505 El M’Naouer, Algeria
Lahouari
Adjlout
Mechanical Engineering Faculty, Laboratoire D'Aero-Hydrodynamique Navale, Departement
de Genie Maritime, Universite des Sciences et de la Technologie d'Oran Mohamed Boudiaf,
Oran, Algeria
vertical axis wind turbine
NACA0018
tandem turbine
power coefficient
The interest in studying windmills is that they are in the renewable energies context which had gained a great importance regarding to the world demand for energy that by 2050, could double or even triple as the global population grows [Vaughn, N., Wind Energy, Renewable Energy and the Environment, London: Taylor & Francis Group, 2009]. In this background, this paper represents a numerical investigation on a new vertical axis wind turbine (VAWT) (Darrieus type). The idea proposed was to have more blades on each side of a three-bladed VAWT and to examine how such a configuration would affect the machine's performance. The proposed H-rotor named Tandem turbine is numerically tested. Different configurations are tested to examine the pitch angle effect on the power coefficient (Cp). The validation of the numerical code was made through the comparison of numerical simulations with experimental study of a two-bladed VAWT performed by Laneville and Vittecoq (1986). The blades used are NACA0018. The turbulence model for calculations is the Spalart−Allmaras model. The power coefficients (Cp) have been calculated over a range of specific speeds A chosen between 1.75 and 4.35. Below the value of λ = 3, the tandem turbine with no pitch angle provides higher Cp than the conventional turbine [Kjellin, J., Bulow, F., Eriksson, S., Goude, A., Deglaire, P., Leijon, M., and Bernhoff, H., Power coefficient measurement on a 12 kW straight bladed vertical axis wind turbine, Renewable Energy, vol. 36, no. 11, pp. 3050-3053, 2011]. Such results encourage us to undertake more advanced work on this topic.