Abstract
A generalized similarity transformation procedure was proposed for the analysis of buoyancy-induced flows over a curved heated surface embedded in a thermally stratified porous medium. The analysis considers two-dimensional and axisymmetric non-isothermal smooth bodies of arbitrary geometrical configuration. A generalized similarity variable which adjusts its vertical scaling according to the geometry as well as the surface temperature variation was introduced to show that, for any two-dimensional or axisymmetric smooth body shape, there exists a certain class of the surface and ambient temperature distributions which admit similarity solutions. Subsequently, the set of the governing partial differential equations were transformed into a single ordinary differential equation, which was, then, solved by a standard shooting procedure based on the Runge-Kutta method, for numerous sets of parameters. The results presented here may readily be translated for the problem of free convection over any particular two-dimensional or axisymmetric smooth body within a porous medium. The effects of the surface temperature and thermal stratification on the temperature profile and isotherms were also discussed in connection with the local surface heat flux.
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Abbreviations
- f :
-
dimensionless stream function
- g :
-
acceleration due to gravity
- I :
-
function associated with a deviation from unity
- k :
-
thermal conductivity
- K :
-
permeability
- m :
-
parameter associated with thermal stratification
- Nu x :
-
local Nusselt number
- q w :
-
local surface heat flux
- r :
-
function representing wall geometry
- r*:
-
1 for plane flow andr for axisymmetric flow
- Ra x :
-
local Rayleigh number
- T :
-
temperature
- u, v :
-
Darcian velocity components
- x, y :
-
boundary layer coordinates
- α :
-
thermal diffusivity
- β :
-
coefficient of thermal expansion
- γ :
-
ratio of a horizontal axis to a vertical axis
- η :
-
similarity variable
- λ :
-
parameter associated with the surface temperature increase
- ν :
-
kinematic viscosity
- ξ :
-
transformed variable in the streamwise direction
- ψ :
-
stream function
- e :
-
boundary layer edge
- w :
-
wall
- r :
-
reference
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Nakayama, A., Koyama, H. Similarity solutions for buoyancy-induced flows over a non-isothermal curved surface in a thermally stratified porous medium. Appl. Sci. Res. 46, 309–322 (1989). https://doi.org/10.1007/BF01998548
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DOI: https://doi.org/10.1007/BF01998548