Boundary-layer flows with large injection and heat transfer.

This is the second of two articles by the authors dealing with asymptotic expansions for forced-convection heat or mass transfer to laminar flows. It is shown here how the method of the first paper (Acrivos & Goddard 1965), which was used to derive a higher-order term in the large Péclet number expansion for heat or mass transfer to small Reynolds number flows, can yield equally well higher-order terms in both the large and the small Prandtl number expansions for heat transfer to laminar boundary-layer flows. By means of this method an exact expression for the first-order correction to Lighthill's (1950) asymptotic formula for heat transfer at large Prandtl numbers, as well as an additional higher-order term for the small Prandtl number expansion of Morgan, Pipkin & Warner (1958), are derived. The results thus obtained are applicable to systems with non-isothermal surfaces and arbitrary planar or axisymmetric flow geometries. For the latter geometries a derivation is given of a higher-order term in the Péclet number expansion which arises from the curvature of the thermal layer for small Prandtl numbers. Finally, some applications of the results to ‘similarity’ flows are also presented.

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Heat Transfer in the Turbulent Boundary Layer With a Step Change in Surface Roughness

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/91-gt-266 ◽

1991 ◽

Cited By ~ 5

Author(s):

Robert P. Taylor ◽

J. Keith Taylor ◽

M. H. Hosni ◽

Hugh W. Coleman

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Surface Roughness ◽

Smooth Surface ◽

Plate Boundary ◽

Step Change ◽

Stanton Number ◽

Test Surface ◽

Temperature Profiles ◽

Boundary Layer Flows

Measurements of Stanton numbers, velocity profiles, temperature profiles, and turbulence intensity profiles are reported for turbulent flat plate boundary layer flows with a step change in surface roughness. The first 0.9 m length of the test surface is roughened with 1.27 mm diameter hemispheres spaced 2 base diameters apart in a staggered array. The remaining 1.5 m length is smooth. The experiments show that the step change from a rough to a smooth surface has a dramatic effect on the convective heat transfer. In many cases, the Stanton number drops below the smooth-wall correlation immediately downstream of the change in roughness. The Stanton number measurements are compared with predictions using the discrete element method with excellent results.

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ON A SOLUTION FOR TURBULENT BOUNDARY LAYER FLOWS WITH HEAT TRANSFER, PRESSURE GRADIENTS, AND WALL BLOWING OR SUCTION

10.1615/ihtc4.1970 ◽

1970 ◽

Cited By ~ 2

Author(s):

Richard H. Pletcher

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Turbulent Boundary Layer ◽

Pressure Gradients ◽

Boundary Layer Flows ◽

Transfer Pressure

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