1. Computational fluid dynamic results are _________ wind tunnel results.
a) Better than
b) Analogous to
c) More reliable than
d) Energy consuming when compared to
Explanation: CFD results completely depend on the problem and solution models we opt to simulate the flow. So, if the chosen models are correct, the CFD results will be analogous to experimental results. In fact, by comparing the results with wind tunnel results, CFD models are changed.
2. Which of these characteristics does not apply for a CFD tool?
a) Unwieldy
b) Easy to carry around
c) Can be remotely accessed
d) Transportable
Explanation: A CFD tool just means a computer program that makes it very easy to carry or transfer. Moreover, the source program can even be remotely accessed. This makes it a readily transportable tool. A wind tunnel is a tool which is unwieldy.
3. CFD can be used to ___________ the experimental results.
a) Improve
b) Replace
c) Interpret
d) Convert
Explanation: CFD does not just provide a quantitative comparison with the wind tunnel results. It provides a means to interpret the experimental conditions. For example, to determine whether the flow is laminar or turbulent in a quantitative experiment carried out in a wind tunnel.
4. CFD carries out ___________ experiments.
a) Observational
b) Analytical
c) Field
d) Numerical
Explanation: CFD uses numerical experimentation to obtain the flow properties at discrete points. Computer programs are used to carry out these experiments.
5. ___________ technique is used in a wind tunnel to find whether the flow is laminar or turbulent.
a) Pressure sensitive paint
b) Force measurement
c) Flow visualization
d) Quantitative
Explanation: A flow can be categorized into laminar or turbulent by seeing it. So, the flow of air should be made visible by some flow visualization techniques. In the case of CFD, it can be easily seen from the resulting plot of flow properties.
6. In the early days, CFD simulations were limited to two-dimensional analyses. Three-dimensional analyses could not be performed because of _________
a) Complex mathematical models were not resolved
b) Governing equations were not developed for three-dimensions
c) Approximations for three-dimensions did not exist
d) The type of computers and algorithms that existed
Explanation: The computers and algorithms that existed that time was not suitable for three-dimensional analyses. Storage and speed capacities of computers were not enough.
7. Which of these problems does not require three-dimensional analysis?
a) Internal flow in SCRAM jet engines
b) Flow over an aircraft wing
c) Flow past gas turbine compressors
d) Flow over airfoils
Explanation: An airfoil is a two-dimensional profile of a wing. Flow over this two-dimensional profile will not need any three-dimensional analysis.
8. The knowledge of pressure distribution is required for ____________ engineers.
a) Aerodynamic
b) Thermal
c) Structural
d) Avionics
Explanation: An aerodynamic engineer needs the pressure distribution, vortex formation and other aerodynamic details to make an aircraft aerodynamically efficient.
9. The knowledge of aerodynamic loads on an aircraft is needed for ___________ engineers.
a) Aerodynamic
b) Thermal
c) Structural
d) Avionics
Explanation: A structural engineer is the one who analyses the loads to be carried and decides the materials for various aircraft parts. So, the loads acting on the parts must be known to him.
10. Aerodynamics engineers obtain the lift and pressure drag by integrating the ___________ distribution over a surface.
a) Velocity
b) Pressure
c) Temperature
d) Viscosity
Explanation: Lift force can be obtained by the difference in pressure between the top and bottom surfaces of a body. Similarly, the pressure drag of a body can be obtained by finding the pressure difference between the front and back halves of a body. Both of these quantities depend upon the pressure distribution.