On fluctuating flow of an elastico-viscous fluid past an infinite plate with variable suction

1969 ◽  
Vol 35 (3) ◽  
pp. 561-573 ◽  
Author(s):  
V. M. Soundalgekar ◽  
Pratap Puri
Keyword(s):  
Skin Friction ◽  
Free Stream ◽  
Infinite Plate ◽  
Porous Wall ◽  
Frequency Parameter ◽  
Stream Velocity ◽  
Suction Parameter ◽  
Suction Velocity ◽  
Elasticity Parameter ◽  
Two Dimensional Flow

An exact solution is obtained for the two-dimensional flow of an elastico-viscous (Walters fluid B’) incompressible fluid past an infinite porous wall under the following conditions: (i) the suction velocity normal to the plate oscillates in magnitude but not in direction about a non-zero mean; (ii) the free-stream velocity oscillates in time about a constant mean.The response of the skin-friction to the fluctuating stream and suction velocity is studied for variations in the suction parameter A, the elasticity parameter k and the frequency parameter μ. It is found that the back-flow at the wall is enhanced by k. For the same value of A, the amplitude of the skin-friction decreases with increasing k. Also an increase in k and μ leads to a decrease in the phase of the skin-friction. For moderately large A and k, the phase of the skin-friction may be completely negative.

Flow Transient Near the Leading Edge of a Flat Plate Moving Through a Viscous Fluid

1974 ◽  
Vol 41 (4) ◽  
pp. 919-924 ◽  
Author(s):  
R. B. Kinney ◽  
M. A. Paolino
Keyword(s):  
Free Stream ◽  
Infinite Plate ◽  
Leading Edge ◽  
Viscous Flows ◽  
Stream Velocity ◽  
Viscous Layer ◽  
Two Dimensional Flow ◽  
Essential Input ◽  
Vorticity Production ◽  
Vorticity Transport

An investigation is made of the unsteady flow in the leading-edge region of a semi-infinite plate impulsively started from rest. Based entirely on the vorticity concepts outlined by Lighthill, numerical results are obtained for the complete two-dimensional flow field by solving the single vorticity transport equation. An essential input to the calculations is the distribution of vorticity production at the plate surface. This is determined at each instant of time from the no-slip condition at the plate and represents a departure from conventional numerical analyses of viscous flows. Departing further from conventional approaches, the velocity field is computed from the law of induced velocities (Biot-Savart law) rather than the stream function. Because of vorticity diffusion well ahead of the plate, a significant disturbance propagates upstream, thereby destroying the uniformity of the approaching flow. Calculations are carried sufficiently forward in time for an approximately steady state to be reached at a distance downstream of the leading edge equal to the thickness of the viscous layer. As viewed by an observer moving with the plate, the flow transient exhibits a velocity overshoot relative to the apparent free-stream velocity. This effect was unexpected for a semi-infinite plate and represents a novel aspect of the flow not found in transient analyses based on the boundary-layer approximations.

scholarly journals Added mass of a circular cylinder oscillating in a free stream

2013 ◽  
Vol 469 (2156) ◽  
pp. 20130135 ◽  
Author(s):  
Efstathios Konstantinidis
Keyword(s):  
Circular Cylinder ◽  
Free Stream ◽  
Transverse Velocity ◽  
Inertial Force ◽  
Added Mass ◽  
Stream Velocity ◽  
Virtual Experiment ◽  
Classical Formulation ◽  
Fundamental Understanding ◽  
Two Dimensional Flow

The fundamental understanding of the added mass phenomenon associated with the motion of a solid body relative to a fluid is revisited. This paper focuses on the two-dimensional flow around a circular cylinder oscillating transversely in a free stream. A virtual experiment reveals that the classical approach to this problem leads to a paradox. The inertial force is derived afresh based on analysis of the motion in a frame of reference attached to the cylinder centroid, which overcomes the paradox in the classical formulation. It is shown that the inertial force depends not only on the acceleration of the cylinder per se , but also on the relative motion between body and fluid embodied in a parameter called alpha, α , which represents the ratio of the maximum transverse velocity of the cylinder to the free-stream velocity; the induced inertial force is directionally varying and non-harmonic in time depended on the alpha parameter. It is further shown that the component of the inertial force in the transverse direction is negligible for α <0.1, increases quadratically for α <0.5, and tends asymptotically to the classical result as , i.e. in still fluid.

scholarly journals Surface temperature and free-stream velocity oscillation effects on mixed convention slip flow from surface of a horizontal circular cylinder

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 13-23
Author(s):  
Zia Ullah ◽  
Muammad Ashraf ◽  
Saqib Zia ◽  
Ishtiaq Ali
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Surface Temperature ◽  
Skin Friction ◽  
Slip Velocity ◽  
Free Stream ◽  
Slip Flow ◽  
Stream Velocity ◽  
Velocity Oscillation

The present phenomena address the slip velocity effects on mixed convection flow of electrically conducting fluid with surface temperature and free stream velocity oscillation over a non-conducting horizontal cylinder. To remove the difficulties in illustrating the coupled PDE, the primitive variable formulation for finite dif?ference technique is proposed to transform dimensionless equations into primitive form. The numerical simulations of coupled non-dimensional equations are exam?ined in terms of fluid slip velocity, temperature, and magnetic velocity which are used to calculate the oscillating components of skin friction, heat transfer, and cur?rent density for various emerging parameters magnetic force parameter, ?, mixed convection parameter, ?, magnetic Prandtl number, ?, Prandtl number, and slip factor, SL. It is observed that the effect of slip flow on the non-conducting cylinder is reduced the fluid motion. A minimum oscillating behavior is noted in skin friction at each position but maximum amplitude of oscillation in heat transfer is observed at each position ? = ?/4 and 2?/3. It is further noticed that a fluid velocity increas?es sharply with the impact of slip factor on the fluid-flow mechanism. Moreover, due to frictional forces with lower magnitude between viscous layers, the rise in Prandtl number leads to decrease in skin fiction and heat transfer which is physi?cally in good agreement.

Skin Friction and Heat Transfer for Laminar Boundary-Layer Flow With Variable Properties and Variable Free-Stream Velocity

1953 ◽  
Vol 20 (3) ◽  
pp. 415-421
Author(s):  
S. Levy ◽  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Prandtl Number ◽  
Skin Friction ◽  
Laminar Boundary Layer ◽  
Boundary Layer Flow ◽  
Free Stream ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Layer Flow

Abstract Numerical solutions of the momentum and energy equations are presented for particular types of laminar boundary-layer flow analogous to the Hartree “wedge flows.” Variation of the viscosity and of the thermal conductivity is considered under the circumstances of no dissipation, favorable pressure gradient, and the product of conductivity and density a constant. The solution is based on approximate representations of the velocity and temperature profiles in the boundary layer and these are of such character that the labor of calculation is minimized and the accuracy of the results preserved. The differential equations are reduced to two algebraic equations which rapidly yield the skin friction and the heat transfer in terms of the wall to free-stream temperature ratio for the desired value of Prandtl number. Numerical results are given for a range of wedge flows with gases of Prandtl number 0.70 and 1.0. These results reveal that when the free-stream velocity is variable the temperature difference between the wall and the free stream exerts a substantial effect on the velocity distribution in the boundary layer and on the skin-friction coefficient. Alternatively, the heat-transfer coefficient is not affected radically. A calculation method is presented for the determination of the heat transfer and skin friction for a flow with an arbitrary variation of velocity over an isothermal surface. This method utilizes the results of the present analysis for the variable property wedge flows.

scholarly journals MHD Flow of a Stratified Dusty Fluid in Porous Medium Past an Infinite Porous Vertical Plate

2020 ◽  
Vol 9 (3) ◽  
pp. 3263-3267
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Skin Friction ◽  
Vertical Plate ◽  
Free Stream ◽  
Liquid Velocity ◽  
Mhd Flow ◽  
Time Dependent ◽  
Dust Particles ◽  
Suction Velocity

In this article, MHD flow of a stratified dusty viscous fluid through a porous medium past an infinite porous vertical plate with time dependent suction has been investigated assuming that the free stream oscillates about a constant mean and suction velocity as exponentially decreasing function of time. The liquid velocity, particle velocity and skin friction for liquid and dust particles have been obtained. The effect of magnetic field, Grashoff number, permeability and stratification factor on velocity profiles and skin friction have been discussed with the help of graphs and tables.

scholarly journals Surface temperature and free-stream velocity oscillation effects on mixed convention slip flow from surface of a horizontal circular cylinder

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 13-23
Author(s):  
Zia Ullah ◽  
Muammad Ashraf ◽  
Saqib Zia ◽  
Ishtiaq Ali
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Surface Temperature ◽  
Skin Friction ◽  
Slip Velocity ◽  
Free Stream ◽  
Slip Flow ◽  
Stream Velocity ◽  
Velocity Oscillation

The present phenomena address the slip velocity effects on mixed convection flow of electrically conducting fluid with surface temperature and free stream velocity oscillation over a non-conducting horizontal cylinder. To remove the difficulties in illustrating the coupled PDE, the primitive variable formulation for finite dif?ference technique is proposed to transform dimensionless equations into primitive form. The numerical simulations of coupled non-dimensional equations are exam?ined in terms of fluid slip velocity, temperature, and magnetic velocity which are used to calculate the oscillating components of skin friction, heat transfer, and cur?rent density for various emerging parameters magnetic force parameter, ?, mixed convection parameter, ?, magnetic Prandtl number, ?, Prandtl number, and slip factor, SL. It is observed that the effect of slip flow on the non-conducting cylinder is reduced the fluid motion. A minimum oscillating behavior is noted in skin friction at each position but maximum amplitude of oscillation in heat transfer is observed at each position ? = ?/4 and 2?/3. It is further noticed that a fluid velocity increas?es sharply with the impact of slip factor on the fluid-flow mechanism. Moreover, due to frictional forces with lower magnitude between viscous layers, the rise in Prandtl number leads to decrease in skin fiction and heat transfer which is physi?cally in good agreement.

scholarly journals Unsteady Convection Flow of a Magnetomicropolar Fluid Past a Vertical Porous Plate

2013 ◽  
Vol 18 (1) ◽  
pp. 43-53
Author(s):  
N.C. Jain ◽  
P. Gupta ◽  
B. Sharma
Keyword(s):  
Free Stream ◽  
Slip Flow ◽  
Porous Plate ◽  
Transverse Magnetic ◽  
Temperature Fields ◽  
Convection Flow ◽  
Stream Velocity ◽  
Time Varying ◽  
Suction Velocity ◽  
Source Sink

The paper deals with an unsteady two dimensional laminar slip flow of a viscous incompressible magnetomicropolar fluid past a semi infinite porous plate embedded in a porous medium. The flow is under the influence of a transverse magnetic field and heat source/sink. The free stream velocity follows an exponentially increasing or decreasing small perturbation law. The porous surface absorbs the fluid with time varying suction velocity. Expressions are obtained for velocity and temperature fields, mean angular velocity, skin friction and the Nusselt number.

Parametric Study for Optimization of Blowing and Suction Locations for Improving Lift-to-Drag Ratio on a Clark-Y Airfoil

2019 ◽  
Author(s):  
Masahiro Ohashi ◽  
Yuki Morita ◽  
Shiho Hirokawa ◽  
Koji Fukagata ◽  
Naoko Tokugawa
Keyword(s):  
Free Stream ◽  
Rear Surface ◽  
Lower Surface ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Friction Drag ◽  
Suction Velocity ◽  
Combined Control ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract In this study, Reynolds-averaged Navier-Stokes simulation (RANS) of the uniform blowing and suction (UB/US) control on a Clark-Y airfoil was performed aiming at improving an airfoil performance by friction drag reduction. First, the control effect when only the uniform blowing control or uniform suction control is applied on the airfoil surface was investigated by changing the control locations. The blowing or suction velocity was 0.14% of the free-stream velocity and the blowing/suction area was set at four different locations from the leading edge to the trailing edge on both the upper and lower surfaces. The Reynolds number based on the chord length is 1.5 × 106. The angle of attack is set to 0°. It was found that friction drag is decreased/increased by single UB/US control. It was also found that the lift-to-drag ratio improved with UB on the lower surface or US on the upper surface, and decreased with UB on the upper surface or US on the lower surface. In the combined control of UB and US, the blowing and suction velocity was 0.14% or 0.26% of the free-stream velocity and the locations of blowing/suction and flow conditions were the same as those in the cases with either UB or US. It seemed that the lift-to-drag ratio was improved by the combined control of UB on the lower surface and US on the upper surface. In particular, the lift-to-drag ratio was most improved by US on the lower rear surface and UB on the upper rear surface.

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