Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
42
3
2015
Numerical Investigation of Dynamic Response of Deploying System during a Circular Cylinder Lowering through Air-Water Interface
191-205
Xiaozhou
Hu
College of Mechanical and Electrical Engineering, Central South University, Key Laboratory of Modern Complex Equipment Design and Extreme Manufacturing Changsha 410083, Hunan, China
Shaojun
Liu
College of Mechanical and Electrical Engineering, Central South University, Key Laboratory of Modern Complex Equipment Design and Extreme Manufacturing Changsha 410083, Hunan, China
Dynamic response of deployment system after a circular cylinder impacting with initial calm water during deploying operation is numerically investigated.
The discretization of the RANS equations is achieved by a finite volume approach (FV), and the volume of fluid method (VOF) is employed to track the complicated
free surface. A 1-Degree-of-freedom (1-DOF) approach is applied to investigate the dynamic problem of cable-deployed body system. An integral solution platform
based on CFD code and MATLAB is built to study the fluid-solid coupling problem in the process of deployed body deploying through air-water interface. Several simulations are performed based on the integral solution platform. The
sensitivity of cable tension, velocity and acceleration of deployed body to different input parameters is studied, including weights of circular cylinder, deploying
velocities and stiffness of cable. Time histories of velocity, acceleration and tension of circular cylinder during its lowering through water surface are presented,
and relationship between them and input parameters are discussed. The numerical results can provide references for the deploying operation of offshore structures.
On Existence of General Solution of the Navier − Stokes Equations for 3D Non-Stationary Incompressible Flow
206-213
Sergey V.
Ershkov
Institute for Time Nature Explorations, M.V. Lomonosov's Moscow State University
The paper deals with presenting the new form of general solution for the Navier−Stokes equations. The equations of motion for a 3D non-stationary incompressible
flow are considered. The flow velocity field and the equation of momentum should be split to the sum of two components: the irrotational (curl-free) one, and solenoidal (divergence-free) ones. The obviously irrotational (curl-free) part of equation of momentum is used for obtaining of the components of pressure
gradient. The irrotational (curl-free) vector field of flow velocity is given by the proper potential according to the continuity equation. Another part of equation
of momentum could also be split to the sum of two equations: one with zero curl for the field of flow velocity (viscous-free) and proper equation with the viscous effects but variable curl. A solenoidal equation with the viscous effects is represented by the proper heat equation for each component of a flow velocity with
variable curl. The non-viscous case is presented by the system of three linear partial differential equations with respect to the time-parameter, depending on the
components of solution of the above heat equation for the component of flow velocity with the variable curl. So, the existence of general solution of the Navier−Stokes equation is proved to be the question of existence of the proper solution of Riccati-type for such a system of linear partial differential equations. The final solution is proved to be the sum of the irrotational (curl-free) and solenoidal (variable curl) components.
Vortex Suppression behind a Heated Circular Cylinder Placed between Parallel Walls by Applying Magnetic Field on a Magnetic Nanofluid Flow
214-226
Sajjad Ahangar
Zonouzi
Department of Mechanical Engineering, Razi University Kermanshah, Iran
Najaf
Biglari
Department of Mechanical Engineering, Razi University Kermanshah, Iran
Mousa
Mohammadpourfard
University of Tabriz
Habibollah
Safarzadeh
Department of Mechanical Engineering, Razi University Kermanshah, Iran
This paper presents numerical investigation of water-Fe3O4 ferrofluid flowing
over a heated circular cylinder located between parallel walls and the effect of applying non-uniform axial magnetic field on the hydro-thermal behavior of the
flow is investigated using two phase mixture model and control volume technique. The obtained results shows that the appeared vortices behind the cylinder due to
flow over the cylinder are influenced by the applied non uniform magnetic field and they can be weakened or get completely suppressed by the applied magnetic
field. Applying the magnetic field also enhances the local heat transfer coefficient and the local friction factor over the heated cylinder wall considerably.
Hydrodynamic Characteristics of a Butterfly Valve Controlling Al2O3/Water Nanofluid Flow
227-235
Mohamed H.
Shedid
Department of Mechanical Engineering, Faculty of Engineering at El-Mattaria, Helwan University Cairo, Egypt
This paper investigates computationally the reliability of the valve loss coefficient
and torque coefficient of butterfly valves when the flow is Al2O3/water nanofluid. The model is constructed and discretized according to five opening
angles of 0, 20, 30, 55, and 75°. Three different inlet velocities of 1, 2 and 3 m/s were tested. The study was carried out numerical analysis using commercial CFD
code FLUENT. The results revealed that the valve loss and torque coefficients are unreliable in design of the butterfly valves.
Hydrodynamic Aspects of Laminar Submerged Buoyant Jets: Effect of Jet Inclinationy
236-259
Nirmalendu
Biswas
Department of Mechanical Engineering, Jadavpur University Kolkata, 700032, India
Souvick
Chatterjee
Department of Engineering Science and Mechanics, Virginia Tech Blacksburg, VA 24061, USA
Rakesh P.
Sahu
Department of Mechanical Engineering, University of Illinois Chicago, 60607, USA
Prokash C.
Roy
Department of Mechanical Engineering, Jadavpur University Kolkata, 700032, India
Achintya
Mukhopadhyay
Department of Mechanical Engineering Jadavpur University Kolkata, West Bengal, 700032, India
Swarnendu
Sen
Department of Mechanical Engineering, Jadavpur University, Kolkata 700032, India
An extensive investigation has been carried out to study the trajectory and other hydrodynamic aspects of non-confined submerged laminar buoyant jet issuing
from inclined circular nozzle into isothermal ambient medium. Brine solution of different densities and fresh water have been used as the experimental fluids
and flow diagnosis has been performed using Particle Image Velocimetry (PIV) and shadow graphy technique. The experimental results are considered in terms of
the basic physical mechanisms which govern the buoyant jet flow characteristics. Based on the integral approach, a simple analytical model is developed to predict
essential hydrodynamic aspect. The predicted jet centerline trajectory as well as the jet periphery obtained using analytical techniques are found to agree quite well with the experimental results. A detailed comprehensive integral analysis of the hydrodynamic aspect highlighting relative importance of associated parameters is addressed in this work. The effect of jet inclination, fluid injection velocity and the density difference between the fluids on jet trajectory for both positively and negatively buoyant jet are explicitly studied. The flow field reveals several interesting features like flow entrainment into the jet, terminal height, downward penetration.
Analysis of Steady and Physiological Pulsatile Flow Characteristics in an Artery with Various Percentages of Restrictions
260-280
P.
Goswami
Department of Mechanical Engineering, Jadavpur University Kolkata, 700032, West Bengal, India
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
Nirmal Kumar
Manna
Department of Mechanical Engineering, Jadavpur University Kolkata, 700032, West Bengal, India
Somnath
Chakrabarti
Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology Shibpur, Howrah, 711103, West Bengal, India
Atherosclerosis, a progressive process, silently and slowly restricts the blood flow through artery. The flow characteristics of blood in the artery are important
factors in the progression and formation of atherosclerosis. A numerical simulation has been carried out for analysis of steady and physiological pulsatile blood flow characteristics in a modeled artery for various percentage of restrictions in
the lumen area of artery. The continuity and momentum equations have been solved by finite volume method considering blood as Newtonian fluid and stenosis
as bell shaped in nature. The flow characteristics such as time averaged wall pressure, stream line contour and time averaged wall shear stress have been analyzed
for different percentage of restriction and compared for both type of flows. The flow characteristics significantly vary with the percentage of restriction. The post-stenotic regions are occupied by the vortex rings for higher percentage of restriction.
The maximum time averaged pressure drop and the peak time averaged wall shear stress are found to be located at the stenosis throat for all type of flows and restrictions. The study shows that steady flow characteristics are dominated by physiological pulsatile flow characteristics from the perspective of atherosclerosis.
The time averaged wall pressure drop, the size of recirculation zone and the peak wall shear stress increase with increase in percentage of restriction. Thus
chances of progression and formation of atherosclerosis increase with increase in percentage of restriction.