Convective Heat Transfer Questions & Answers  




I only answer questions written within the post, not within the attachments.. Or, you can come see me in my office.




The exam is already officially scheduled on the department homepage so the date can not be changed anymore. In your case, because you can not attend the midterm exam, the final exam will be worth more points.




Hm, I don't understand fully the question. The stresses acting on the fluid element are $\tau_{xx}$, $\tau_{yx}$, etc and not $d\tau_{xx}/dx$, etc. Also, what is $u_{yx}^\prime$?




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.




Yes $x=x_0$ is the location where the thermal layer starts while $x=0$ is where the momentum layer starts. In the derivation we did in class, I mentioned to you that $\delta_t<\delta$ at $x=0$ not that $\delta_t<\delta$ at any $x$. This is because the thermal layer is assumed to start just a bit downstream of the momentum layer. Whether $\delta_t$ is smaller or larger than $\delta$ for a large $x$ depends on the Prandtl number.



$\pi$ 