Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
42
2
2015
Surge Motion Coefficients for a Finite Circular Hollow Cylinder Radiating in Water of Infinite Depth
95-110
10.1615/InterJFluidMechRes.v42.i2.10
M.
Hassan
Department of Mathematics, Indian
Institute of Technology Guwahati Guwahati 781039, India
S. N.
Bora
Department of Mathematics, Indian Institute of Technology Guwahati Guwahati 781039, India
Within the framework of linear water wave theory, the radiation of water waves by a hollow circular cylinder in an infinite depth ocean is considered. The whole fluid domain is divided into two regions: interior and exterior regions. Using separation of variables technique, Fourier sine transform and Havelock's expansion theorem, the radiated potentials in each region are obtained, and consequently the added mass, the damping coefficients and phase angles are evaluated for different wavenumbers and different drafts of the cylinder. It is observed that mostly the added mass are significant only at lower frequencies while the damping coefficients attain higher values in the middle range of frequencies. The added mass almost vanish at higher frequencies. All the results are depicted graphically.
A Vorticity Based Model of Isotropic Turbulence
111-118
10.1615/InterJFluidMechRes.v42.i2.20
Amitabha
Chanda
Faculty (Retd.), Indian Statistical Institute Presently Visiting Faculty, UCSTA, University of Calcutta India
It is argued that the transfer operator in the governing equation of isotropic turbulence is engaged in convection of turbulent energy. Pursuing this argument the transfer operator is replaced by a constant multiplier and vorticity of dimension same as that of the transfer operator. Thereafter the general decay of isotropic turbulence is studied. An expression of longitudinal correlation coefficient is found and plotted against the separation distance between two close points of measurement. The new result is compared with the standard one.
The Effect of Wall Groove Numbers on Pressure Drop in Pipe Flows
119-130
10.1615/InterJFluidMechRes.v42.i2.30
Putu Wijaya
Sunu
Department of Mechanical Engineering, Brawijaya University, Malang East Java, Indonesia; Department of Mechanical Engineering, Bali State Polytechnic Badung, Bali, Indonesia
I. N. G.
Wardana
Mechanical Engineering Department, Brawijaya University Jln. MT. Haryono 167, Malang 65145, Indonesia
A. A.
Sonief
Department of Mechanical Engineering, Brawijaya University, Malang East Java, Indonesia
Nurkholis
Hamidi
Department of Mechanical Engineering, Brawijaya University, Malang East Java, Indonesia
Flow behavior in pipe with rectangular grooves on internal wall surface has been investigated experimentally. The number of grooves was varied to clarify its influence on pressure drop. In this experimental design, dyes were injected from pipe walls and plastic threads attached to internal pipe walls to enable observation of their movements in flowing water. Results show that pipe wall grooves, described as 2n and 2n + 2m did induce pressure drops. When n is the odd positive integer the groove produces weak vortices of low momentum viscous fluid on the wall which diameter is larger than the groove spacing. Therefore, it is swept by large-scale motion from the center of the pipe then pressure drop decreased. However, when n equals to the even positive integer the groove produces energetic small vortices of high viscous fluids that rotates around the pipe wall and induces high momentum fluid from the center of the pipe. As a result, the radial velocity increased as did the pressure drop. m represented the motion that interrupting flow behavior caused by n. When n is the odd positive integer, the vortex behavior represented with m tended to increase the pressure drop produced by n. On the other hand, when n is the even positive integer, m tended to decrease pressure drop produced by n.
Turbulent Mixing of Subsonic Hot and Cold Air Jets
131-148
10.1615/InterJFluidMechRes.v42.i2.40
V.
Ilangovan
Department of Mechanical Engineering, Karpaga Vinayaga College of Engineering and Technology Tamilnadu, 603319, India
An experimental investigation of mean and turbulent flow fields resulting due to the interaction of subsonic, axisymmetric, hot and cold air jets in coaxial configuration has been reported. The basic characteristics of turbulent jets such as axial spread, radial growth and centre line decay of flow variables were altered remarkably with addition of heat. When the Gaussian shape of the normalized mean velocity distribution across the jet was not significantly affected by the heating, the local values of mean axial velocity were different for different levels of heat addition. The increase in entrainment in the initial region is due to the combined effect of mechanisms such as a large amount of small-scale vorticity, strong acceleration of jet due to density difference and larger radial expansion Based on the experimental data, a correlation was developed to predict the variation in entrainment ratio for different heating levels. The spatial variation of turbulent Prandtl number, a parameter that compares the relative rates of turbulent momentum and turbulent heat transfer, is found to be dependent on temperature ratio.
Computational Analysis of Transient non-Newtonian Blood Flow in Magnetic Targeting Drug Delivery in Stenosed Carotid Bifurcation Artery
149-169
10.1615/InterJFluidMechRes.v42.i2.50
Haleh
Alimohamadi
PhD student
Mohsen
Imani
School of Electrical and Computer Engineering, University of Tehran Tehran, Iran
Behjat
Forouzandeh
School of Electrical and Computer Engineering, University of Tehran Tehran, Iran
This paper presents pulsatile blood flow simulation in a carotid bifurcation under the action of external magnetic field. Previous investigations neglected the effect of transient magnetic field on non-Newtonian blood flow through a coupled free and porous media. In this study for closing to a real phenomenon, arterial walls and two fatty deposited atherosclerotic plaques are considered as different porous media, blood is assumed as a generalized non-Newtonian biomagnetic fluid (with Power law and Carreau models) and time dependent inlet velocity varies by the frequency of human heart beating cycle. Because of magnetic field existence, two big vortexes are created at the plaques' edges and the temperature, shear stress, vertical velocity and pressure distribution along the stenosis region have been affected noticeably. The results show by applying MnF = 107 and MnM = 102 magnetic field intensity the values of temperature, absolute maximum pressure and shear stress go up 7.35 %, 5.55 times and 5.33 times (62.16 %,4.08 times and 6 times) respect with normal condition on the upper (lower) plaques respectively. Examining the role of porosity factor indicates that by progressing stenosis disease and hardening atherosclerotic plaques, magnetotherapy treatment lose its efficiency due to sever reduction in available maximum blood temperature, fluid flux and average Nusselt number.
Stokes Flow of Micropolar Fluid Past a Non-Newtonian Liquid Spheroid
170-189
10.1615/InterJFluidMechRes.v42.i2.60
Bharat Raj
Jaiswal
Department of Mathematics, AKS University, Satna 485001, M.P., India
Bali Ram
Gupta
Department of Mathematics, JaypeeUniversity of Engineering and Tech., Guna 473226, M. P., India.
This paper deals with the problem of creeping, steady, axisymmetric Stokes flow of a viscous incompressible micropolar fluid past a Reiner−Rivlin liquid spheroid whose shape deviates a bit from that of a sphere. The polar equation of the deformed sphere is considered for the present study. The stream function solution for the flow outside the liquid spheroid is obtained in terms of modified Bessel functions and Gegenbauer functions, and for the flow inside the liquid spheroid, the stream function solution is obtained by expanding the stream function in terms of S. The flow fields are determined explicitly by matching the boundary conditions at the interface of the micropolar fluid and the liquid spheroid, and uniform velocity at infinity. As an example, the case of an oblate liquid spheroid is considered, and force experienced by it is evaluated. The dependence of drag coefficient on the deformation parameter ε, dimensionless parameter S, viscosities µ1 and µ2, and vortex viscosity κ is discussed for the oblate spheroid and presented graphically. Previous well-known results are then also deduced from the present analysis. It is found that the drag on the oblate spheroid increases with the increase in deformation parameter and cross-viscosity.