31. What does viscosity depend on for Newtonian fluids such
as water or air?
Shear deformation rate.
Both temperature and shear deformation rate.
Neither temperature nor shear deformation rate.
32. Which of the following conditions entails separation of a
Zero wall friction
Zero wall velocity
Infinite wall-normal gradient of streamwise velocity
Zero boundary layer momentum thickness
Zero boundary layer form factor.
Which momentum transport mechanisms are mainly competing within a laminar boundary layer?
Streamwise advection and wall-normal diffusion
Streamwise diffusion and wall-normal advection
Streamwise diffusion and streamwise advection.
Wall-normal advection and wall-normal diffusion.
Wall-normal and streamwise diffusion.
34. How are the integral boundary layer equations obtained?
By integrating the local equations over the boundary
By integrating the local equations along the streamwise coordinate.
By searching for self-similar solutions of the local
By applying the boundary layer hypothesis to the
Navier-Stokes equations in their integral form.
By adding whole wheat to the fluid.
35. How does the momentum thickness evolve for a laminar
boundary layer in the close vicinity of a stagnation point?
It is finite and constant.
It remains of negligible size.
It debuts with a finite value and grows linearly.
It debuts at zero and grows linearly
It debuts at infinity and decreases hyperbolically
What can be said about the friction coecient Cf when
comparing growing laminar and turbulent boundary layers (BLs) developing under the same outer velocity conditions?
It is higher and decreases slowlier for turbulent BL.
It is higher and decreases slowlier for laminar BL.
It is higher but decreases faster for turbulent BL.
It is higher but decreases faster for laminar BL.
None of the others.
37. Theoretical-empirical turbulent friction laws result from
the matching of the velocity profile in what regions/layers
of the turbulent boundary layer universal profile?
Inner and outer regions
Viscous sublayer and buffer region
Buffer region and log-law layer
Viscous sublayer and log-law layer
Buffer region and inner region.
38. Which of the following phenomena can be ultimately ascribed to the action of viscosity?
All of them
39. Which of the following actions might be beneficial in terms
of drag coefficient reduction of a streamlined body (e.g.
flat plate at alpha = 0) with a laminar boundary layer naturally developing on its surface?
Preserving laminarity of the boundary layer all the
way down to the trailing edge.
Artificially triggering turbulent transition in the
boundary layer before it separates.
Reducing the Reynolds number
Favouring surface rugosity.
None of the others.
40. Which of the following is NOT a consequence of the boundary layer hypothesis?