When viscous dissipation is appreciable, the conservation of energy equation 4.6 in the text must take into account the rate at which mechanical energy is irreversibly converted to thermal energy due to viscous effects in the fluid. This gives rise to an additional term, ?, on the right-hand side, the viscous dissipation where

Apply the resulting equation to laminar flow between two infinite parallel plates, with the upper plate moving at a velocity U. Assuming the constant physical properties [ρ, cp, k, μ], obtain expressions for the velocity and temperature distributions. Compare the solutions with the dissipation term included with the results when dissipation is neglected. Find the plate velocity required to produce a 1 K temperature rise in nominally 40?C air relative to the case where dissipation is neglected.GIVENLaminar flow between two infinite parallel platesUpper plate moves at a velocity U??The viscous dissipation term given above must be used in the conservation of energy equationASSUMPTIONSSteady stateConstant physical propertiesThe plates are at constant temperatures, T1,T2

Transcribed Image Text:

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