EGN 6812  Fluid Mechanics I – Fall 2005
10/11/05, Exam 1
Name: ______________________
1/11
Questions:
(20 points total, 4 points each, unless otherwise marked)
1.
Provide a physical explanation
of Stokes’ hypothesis (
i.e.,
not an equation) and describe
when it is and is not valid for the specific case of a polyatomic molecule in a
compressible
flow
.
2.
()
j
ij
i
uT
x
∂
∂
is the surface work term due to surface forces in the energy equation.
Mathematically decompose this term into pressure and viscous forces.
Then further
decompose this into components that increase/decrease kinetic and internal energy.
Clearly
label your terms and explain your answer in terms of forces, velocities, and deformations
.
3.
At a planar air/water interface, what are the appropriate boundary conditions for the
continuity and momentum equations for incompressible flow without mass transfer?
What
approximations can be made?
What additional forces would become important if the
interface was curved?
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View Full DocumentEGN 6812  Fluid Mechanics I – Fall 2005
10/11/05, Exam 1
Name: ______________________
2/11
Questions:
(20 points total, 4 points each, unless otherwise marked)
4.
Considering both length scale and time scale
arguments, state when the continuum
assumption is not valid?
5.
The coefficient of viscosity is strictly a function of pressure and temperature.
What is the
dependence for increasing/decreasing pressure and temperature for the dynamic viscosity for
both a gas and a liquid
?
Please provide a physical explanation.
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 Fall '09
 RENWEIMEI
 Fluid Dynamics, Fluid Mechanics, Aerodynamics

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