EAS 4101  Aerodynamics – Spring 2008
04/04/08, Exam # 2
Name: __________________________________
1
I. TRUE/FALSE (7 points total  1 point each)
1. Momentum and energy are transferred by molecular diffusion in turbulent flow.
2. Fluid particles within a viscous boundary layer near a solid wall are rotational and, hence, posses vorticity.
3. In Couette flow, the source of the flow is caused by the boundary conditions.
4. In Hagen Poiseuille flow, pressure balances shear stress.
5. Skin friction drag is mainly due to axisymmetric pressure distribution largely due to separation.
6. Laminar boundary layers are thicker than turbulent boundary layers.
7. Turbulent boundary layers have higher skin friction than laminar boundary layers.
II. MULTIPLE CHOICE (6 pts total  3 pts each unless otherwise marked): There may be more than one
correct answer. To receive full credit, circle ALL of the correct answers.
7. Which assumption(s) is(are)
NOT
used to derive the boundary layer equations:
a) 2D
b) Incompressible
c) Fully developed
d) Irrotational
e) Inviscid
f) Steady
8. What assumption(s) is(are) required to transform the NavierStokes Equations into Euler’s equations?
a) Fully Developed
b) Incompressible
c) Inviscid
d) Irrotational
e) Steady
III. SHORT ANSWER (33 pts total  3 pts each unless otherwise marked): Answer all parts of the question to
receive full credit.
9. What does the Reynolds number represent the ratio of in terms of typical forces?
10. What is the
dx
dp
term equal to in the “boundary layer” equations (reduced form of the NavierStokes
equations) for a boundary layer possessing an edge velocity of
U
?
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 Spring '08
 Sheplak
 Fluid Dynamics, Aerodynamics, Inviscid, incompressible

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