Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
34
2
2007
Study of the Flow and Acoustic Fields in a Rigid-Walled Channel of Circular Cross-Section with a Local Axisymmetric Narrowing: A Theory
99-114
A. O.
Borisyuk
Institute of Hydromechanics of the National Academy of Sciences of Ukraine, Zhelyabov Str., 8/4, 03680, Kyiv-180, MSP, Ukraine
The analytical and numerical method is developed for solving the problems of noise generation by flows in channels with local geometrical inhomogeneities. The obtained fields of hydrodynamic parameters are used in this method to describe the noise sources, and the Green's function technique and eigenfunction method, as well as the methods of correlation and spectral analysis are applied to find the flow and acoustic fields. Based on the method developed, the problem of noise generation by a steady flow in an infinite straight rigid-walled channel of circular cross-section with local axisymmetric narrowing is solved, and analytical expressions for hydrodynamic and acoustic characteristics of the flow are obtained.
Theoretical and Numerical Investigation of Oscillation and Switch in a Sonic Oscillator
115-128
Shengtao
Chen
Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China
Dapeng
Hu
Department of Chemical Machinery, Dalian University of Technology Dalian 116024, China
Zuzhi
Chen
Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China
Yuqiang
Dai
Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China
Runjie
Liu
Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China
Che
Zhu
Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China
A periodic and oscillatory flow state in a sonic oscillator is studied in detail. In this paper, the physical model of a sonic oscillator is set up to demonstrate the flow state. Detailed theoretical analysis is made. Numerical simulation of the switch of the jet flow in a sonic oscillator is also done. Emphasis is placed on the factors affecting the switch of the jet flow. Both the momentum supplement to the low-pressure vortex area and the pressure wave in the controlling pipe are contributing.
Effects of Thermal Radiation on Natural Convection in a Porous Medium
129-144
Mohamed F.
El-Amin
Mathematics Department, Aswan Faculty of Science, South Valley University, Aswan, 81258; King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
Ibrahim
Abbas
Mathematics Department, Sohag Faculty of Science, South Valley University, Sohag
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
An analysis is presented for the thermal radiation effect on the non-Darcy natural convection over a vertical flat plate in a fluid saturated porous medium. Forchheimer extension is considered in the flow equations. Rosseland approximation is used to describe the radiative heat flux in the energy equation. The nondimensional governing partial equations are solved by the finite element method. The resulting nonlinear integral equations are linearized and solved by the Newton-Raphson iteration. Results for the details of the stream function, velocity and temperature contours and profiles as well as heat transfer rate in terms of Nusselt number are shown graphically.
MHD Effects on Natural Convection in a Micropolar Fluid at a Three-Dimensional Stagnation Point in a Porous Medium
145-158
S.M.M.
EL-Kabeir
Department of Mathematics, Salman bin Abdulaziz University, College of Science and Humanity Studies, Al-Kharj, 11942, Saudi Arabia; Department of Mathematics, Aswan University, Faculty of Science, 81528, Egypt
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
A boundary layer solution is presented for the natural convection in a micropolar fluid in the vicinity of a three-dimensional axisymmetric stagnation point on heated vertical surfaces embedded in a micropolar fluid-saturated porous medium in the presence of a transverse magnetic field. The governing equations for the velocity, microrotation, and temperature fields are solved numerically. A parametric study is made to investigate the influence of the inverse Darcy number parameter Ak, magnetic parameter Mn, and micropolar parameter Δ on skin friction, couple stress, as well as the Nusselt number. Numerical results are shown in graphical and tabular form.
Effect of Restriction and Reynolds Number on the Pressure of Blood of a Stenotic Artery
159-178
Dipak Kumar
Mandal
Deptartment of Mechanical Engineering, College of Engineering & Management, Kolaghat,
P.O: K.T.P.P. Township, Midnapore (E) - 721171, West Bengal, India
Somnath
Chakrabarti
Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology Shibpur, Howrah, 711103, West Bengal, India
Coronary artery disease is the end result of a complex process called atherosclerosis, which is commonly called hardening of the arteries. The pressure of blood in a coronary artery is considered to be one of the important contributors for the formation and progression of atherosclerosis. Therefore, in this paper, the impact of flow Reynolds number and percent stenosis on wall pressure and average pressure of blood near the stenosis in a part of coronary artery is studied considering laminar flow and blood as Newtonian fluid. The two-dimensional steady differential equations for conservation of mass and momentum is solved by finite difference method for Reynolds number ranging from 25 to 375 and percent stenosis from 10 to 90 %. From the study, it is revealed that for all the cases, higher the Reynolds number, higher is the concerned non-dimensional pressure. A sharp variation in dimensionless wall and average pressure has also been noted at the zone of restriction. The variation in non-dimensional wall pressure and average static pressure near the zone of stenosis is higher both for high percent stenosis and low Reynolds number.
Statistical Analysis of the Turbulence Structure Downstream of a Short Roughness Strip
179-190
M. O.
Oyewola
Department of Mechanical Engineering University of Ibadan Ibadan, Nigeria
M. S.
Adaramola
Division of Energy and Process Engineering, Norwegian University of Science and Technology Trondheim, Norway
A. O.
Olaberinjo
Chemical, Petroleum and Gas Department University of Lagos, Nigeria
O. A.
Obiyemi
Department of Mathematics and Statistics Osun State Polytechnics, Iree, Nigeria
The statistical analyses of the measurements of the turbulence structure have been examined in a wall-bounded turbulent flow subjected to a short roughness strip. The results are compared with the undisturbed boundary layer. It is found that the energy distributions among eddies are altered at the presence of the roughness strip, and this alteration lead to a modification of the turbulent structure downstream of the roughness strip. The change is stronger near the wall of the boundary layer.