Make-up Exam
BIEN 501
Make up Exam and answers to it
Date: 04/21/04
1. In the dimensional analysis of the equations of change
a. the equation of change is written in dimensionless form
b. the boundary conditions are written in dimensionless form
c. the initial conditions are written in dimensionless form
d. all of the above.
e. None of the above
[Related to topic 14]
2. For laminar flows of fluids in simple flow systems the boundary conditions at the
Solid-fluid interfaces the fluid velocity equals the velocity with which the solid surface
is moving
a. The above statement is applied to the tangential component of velocity
vector.
b. The above statement is applied to normal component of the velocity
vector.
c. In making the above statement it is assumed that there is no adsorption,
dissolution, evaporation, melting or chemical reaction at the surface
between the two phases.
d. All of the above
e. None of the above
[Related to topic 6]
3. For a fluid with dynamic viscosity of 0.24 kg/m.s and density of 0.8*103 kg/m3 with a
falling film of thickness of 3 mm on a vertical wall, determine Re of the fluid and hence
determine in which flow regime the fluid flow falls into, given that,
if Re<20 the flow is laminar with negligible rippling
if 20<Re<1500 the flow is laminar with pronounced rippling
Re>1500 the flow is turbulent
a. 2.48 and the flow is laminar with negligible rippling
b. 3.92 and the flow is laminar with negligible rippling
c. 20.8 and the flow is laminar with pronounced rippling
d. 1699 and the flow is turbulent
e. none of the above
[Related to topic 7]
4. The substantial time derivative D/Dt =
-1-
a. ∂/∂t + div v
b. ∂/∂t + del v
c. ∂/∂t + v.del2 v
d. ∂/∂t + curl of v
e. None of the above.
[Related to topic 4]
5. The mass balance equation through a fixed volume element Δx,Δy,Δz through which a
fluid is flowing is given as ΔxΔyΔz∂ρ/∂t = ΔyΔz[(ρvx)|x -[(ρvx)|x+Δx] +
ΔyΔx[(ρvy)|y -[(ρvy)|y+Δy] + ΔyΔx[(ρvz)|z -[(ρvz)|z+Δz]
what is the physical meaning of ΔyΔz(ρvx)|x
a. rate of mass entering the volume element through surface at x
b. rate of mass entering the volume element through surface at y
c. rate of mass entering the volume element through surface at z
d. Both b and c
e. None of the above
[Related to topic 11]
6. Boundary layer theory is applied to a flow problem in which
a. the flow surrounding a body is divided into 2 domains- a layer subject to
friction in the neighborhood of the body, and a frictionless region outside this layer.
b. under certain circumstances reverse flow occurs in the immediate proximity
of the surface.
c. the drag problem is solved theoretically which is encountered in a fluid
which is assumed frictionless. (No fluid which is considered frictionless has zero drag
practically which is very important in certain applications like the aircraft industry)
d. all of the above
e. None of the above
[Related to topic 13]
7. For Newton’s law of viscosity, the constant of proportionality is given by
a. velocity of fluid
b. dynamic viscosity of fluid
c. kinematic viscosity of fluid
d. velocity gradient of fluid
e. Both b. and c.
8. For studying flow through porous media, the following equation is used
a. Navier-Stokes flow
b. Euler equation
c. Hagen-Poiseuille equation
d. Stokes flow
e. None of the above.
[Related to topic 6]
9. The method of combining the initial condition and boundary condition at infinity into
-2-
a single boundary condition is called,
a. method of separation of variables
b. method of sinusoidal response
c. method of combination of variables
d. method of similarity solutions
e. Both c. and d.
[Related to topic 2]
10. For planar motion with rectangular co-ordinate system, choose the velocity
components
a. υx = -δφ/δy, υy= +δφ/δx
b. υr = -1/r δφ/δθ, υθ= +δφ/δr
c. υz = -1/r δφ/δr, υr= + 1/r δφ/δz
d. υx = +δφ/δy, υy= -δφ/δx
e. none of the above.
11. For unsteady laminar flow in a circular tube, the correct initial condition is
a. at r=0, υz=∞
b. at r=R, υz=0
c. at t=0, υz=∞
d. at t=0, υz=0, for 0≤ r ≤ R
e. none of the above.
[Related to topic 6]
12. Turbulent flow is observed when
a. film velocity increases, thickness of film decreases, kinematic viscosity
decreases
b. film velocity increases, thickness of film decreases, kinematic viscosity
increases
c. film velocity increases, thickness of film increases, kinematic viscosity
decreases
d. film velocity decreases, thickness of film increases, kinematic viscosity
decreases
e. None of the above.
[Related to topic 6]
13. In the non-Newtonian fluids when η decreases with the increasing rate of shear the
behavior is termed as
a) thixotropic
b) pseudoplastic
c) dilatant
d) Bingham plastic
e) None of the above.
[Related to topic 12]
14. The equation of continuity in fluid mechanics
-3-
a)
b)
c)
d)
e)
is condition of equilibrium in the flow pattern
is an embodiment of the law of thermodynamics
express the relation between work and energy
is an embodiment of the law of conservation of mass
None of the above.
[Related to topic 11]
15. A stream function
a) is defined only for incompressible flow
b) is defined for irrotational flow
c) is defined when the flow is continuous
d) is defined only for steady flow
e) None of the above.
[Related to topic 3]
16. The shell momentum balance is easy to apply when
a) the flow is laminar
b) the flow is rectilinear
c) the flow is curvilinear
d) the flow is viscous
e) None of the above.
[Related to topic 8]
17. The momentum flows into and out of the volume element by two mechanisms
a) convection and conduction
b) convection and molecular transfer
c) conduction and radiation
d) molecular transfer and radiation
e) None of the above.
[Related to topic 11]
18. For a artery branching into two assuming τ is constant if the flow in the branches is
reduced to half of the artery then by what percentage of the original artery radius will the
new radius of the artery branches be
a. 20%
b. 30%
c. 28%
d. 70%
e. None of the above.
[Related to topic 6]
19. For a Newtonian fluid flowing through a tube of length 50 cm calculate the maximum
velocity when the viscosity of the liquid is 4.5 g/cm.s with pressure drop of 50 psi &
radius of 0.2 in.
-4-
a. 11 m/s
b. 9.88 m/s
c. 988 cm/s
d. 110 cm/s
e. None of the above.
[Related to topic 6/12]
20. The blood flow pattern often found at the point where the blood vessel bifurcates and
there is a large angle between main flow direction and vessel wall, that can be observed
as a slow flow reversal on color Doppler sonography is
a. Laminar flow
b. Turbulent flow
c. Boundary layer separation (vortex flow)
d. spiral flow
e. None of the above
[Related to topic 15]
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