Convective Heat Transfer Questions & Answers  
You're correct: not all of the heat generated by V.D. goes to the wall. Some of it goes to heat the free stream (making the thermal layer grow), but this is a small percentage because the thermal layer goes slowly. Nonetheless, keep in mind the equation $q_{\rm w}^"=h(T_{\rm w}-T_{\rm aw})$ is an approximation, not an exact solution.
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