Summary
Effects of free convection currents on the oscillatory flow of a polar fluid through a porous medium, which is bounded by a vertical plane surface of constant temperature, have been studied. The surface absorbs the fluid with a constant suction and the free stream velocity oscillates about a constant mean value. Analytical expressions for the velocity and the angular velocity fields have been obtained, using the regular perturbation technique. The effects of Grashof numberG; material parameters α and β; Prandtl numberP; permeability parameterK and frequency parametern on the velocity and the angular velocity are discussed. The effects of cooling and heating of a polar fluid compared to a Newtonian fluid have also been discussed. The velocity of a polar fluid is found to decrease as compared to the Newtonian fluid.
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Abbreviations
- C p :
-
specific heat at constant pressure
- g :
-
acceleration due to gravity
- G :
-
Grashof number
- K + :
-
permeability of the porous medium
- K :
-
dimensionless permeability
- P :
-
Prandtl number
- t + :
-
time
- t :
-
dimensionless time
- T w + :
-
mean temperature of the surface
- T + :
-
temperature of the fluid
- T +∞ :
-
temperature of the fluid away from the surface
- ϱ:
-
density of the fluid
- μ:
-
viscosity
- μ r :
-
rotational viscosity
- C a ,C d :
-
coefficients of couple stress viscosities
- I :
-
a scalar constant of dimension equal to that of the moment of inertia of unit mass
- x +,y + :
-
coordinate system
- u +,v + :
-
velocity components in thex + andy + directions
- u :
-
dimensionless velocity in thex +-direction
- ω+ :
-
angular velocity component
- ω:
-
dimensionless angular velocity
- n + :
-
frequency of oscillations
- n :
-
dimensionless frequency
- ε:
-
perturbation parameter
- U :
-
a constant velocity
- u 0 :
-
mean velocity
- u 1 :
-
fluctuating part of the velocity
- ω0 :
-
mean angular velocity
- ω1 :
-
fluctuating part of the angular velocity
- T 0 :
-
mean temperature
- T 1 :
-
fluctuating part of the temperature
- β0 :
-
coefficient of the volume expansion
- ν:
-
kinematic viscosity
- νr :
-
rotational kinematic viscosity
- α, β:
-
material parameters characterizing the polarity of the fluid
- v 0 :
-
suction velocity
- ϱ∞ :
-
density of the fluid far from the surface
- y :
-
dimensionless coordinate normal to the surface
References
Brinkman, H. C.: A calculation of the viscous force extended by a flowing fluid on a dense swarm of particles. Appl. Sci. Res.A1, 27–34 (1947).
Yamamoto, K.: Flow of viscous fluid at small Reynolds numbers past a body. J. Phys. Soc. Japan34, 814–820 (1973).
Yamamoto, K., Iwamura, N.: Flow with convective acceleration through a porous medium. J. Engng. Maths.10, 41–54 (1976).
Raptis, A., Tzivanidis, G., Kafousias, N.: Free convection and mass transfer flow through a porous medium bounded by an infinite vertical limiting surface with constant suction. Lett. Heat Mass Transfer8, 417–424 (1981).
Raptis, A., Kafousias, N., Massalas, C.: Free convection and mass transfer flow through a porous medium bounded by an infinite vertical porous plate with constant heat flux. ZAMM62, 489–491 (1982).
Raptis, A.: Unsteady free convective flow through a porous medium. Int. J. Engng. Sci.21, 345–348 (1983).
Raptis, A., Perdikis, C. P.: Oscillatory flow through a porous medium by the presence of free convective flow. Int. J. Engng. Sci.23, 51–55 (1985).
Aero, E. L., Bulygin, A. N., Kuvschinski, E. V.: Asymmetric hydromechanics. J. Appl. Math. Mech.29, 333–346 (1965).
D'ep, N. V.: Equations of a fluid boundary layer with couple stresses. J. Appl. Math. Mech32, 777–783 (1968).
Kamel, M. T., Kaloni, P. N., Tory, E. M.: Two-dimensional internal flows of polar fluids. J. Rheol.23, 141–150 (1979).
Raptis, A.: Effects of couple stresses on the flow through a porous medium. Rheol. Acta21, 736–737 (1982).
Holman, J. P.: Heat transfer, pp. 434. Tokyo: McGraw-Hill/Kogohusha 1976.
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Hiremath, P.S., Patil, P.M. Free convection effects on the oscillatory flow of a couple stress fluid through a porous medium. Acta Mechanica 98, 143–158 (1993). https://doi.org/10.1007/BF01174299
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DOI: https://doi.org/10.1007/BF01174299