Question

5. (5 points) Select ALL statements that are TRUE A. For flows over a flat plate, in the laminar region, the heat transfer coefficient is decreasing in the flow direction B. For flows over a flat plate, in the turbulence region, the heat transfer coefficient is decreasing in the flow direction C. For flows over a flat plate, the transition from laminar to turbulence flow only happens for rough surface D. For flows over a flat plate, if the length of the plate in the flow direction is long enough, the flows will inevitably become turbulent E. In general, turbulence flows have a larger heat transfer coefficient compared to laminar flows 6. (5 points) Select ALL statements that are TRUE A. For the flow in a pipe with constant cross-section area, both hydrodynamic and thermal boundary layer thicknesses increasingly grow in the flow direction B. In the hydrodynamic fully developed region, the mean velocity of the flow becomes constant C. In the thermally fully developed region, the mean temperature of the flow becomes constant D. For internal flows, if Pr>1, the flows become hydrodynamically fully developed before becoming thermally fully developed E. For internal flows, if Pr>1, the flows become thermally fully developed before becoming hydrodynamically fully developed

Answer 1

Answer:

The following statements are true:

A. For flows over a flat plate, in the laminar region, the heat transfer coefficient is decreasing in the flow direction

C. For flows over a flat plate, the transition from laminar to turbulence flow only happens for rough surface

E. In general, turbulence flows have a larger heat transfer coefficient compared to laminar flows 6.

Select ALL statements that are TRUE

B. In the hydrodynamic fully developed region, the mean velocity of the flow becomes constant

D. For internal flows, if Pr>1, the flows become hydrodynamically fully developed before becoming thermally fully developed

Explanation: