The Relation between Fluid Friction and Heat Transfer

We have already seen that the temperature and flow fields are related. Now we seek an expression whereby the frictional resistance may be directly related to heat transfer. 

The shear stress at the wall may be expressed in terms of a friction coefficient 

Equation (5-52) is the defining equation for the friction coefficient. The shear stress may also be calculated from the relation 

Upon comparing Eqs. (5-54) and (5-55), we note that the right sides are alike except for a difference of about 3 percent in the constant, which is the result of the approximate nature of the integral boundary-layer analysis. We recognize this approximation and write 

Equation (5-56), called the Reynolds-Colburn analogy, expresses the relation between fluid friction and heat transfer for laminar flow on a flat plate. The heat-transfer coefficient thus could be determined by making measurements of the frictional drag on a plate under conditions in which no heat transfer is involved. 

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THE RELATION BETWEEN FLUID FRICTION AND HEAT TRANSFER... 

Describe the relation between fluid friction and heat transfer. 

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