Question 10.1: Consider each of the flow situations described and decide whe...
Consider each of the flow situations described and decide whether you would use a computational analysis, experiments, or both to predict the flow characteristics.
A. Predict the reentry aerodynamics of a probe entering the atmosphere on Jupiter.
B. Investigate a manufacturer’s claim that their new golf ball will add 10 yards to your drive. C. Predict lift and drag for the wing of a next-generation passenger airplane.
D. Analyze the deposition of an airborne toxin in the human respiratory system
A. Owing to the difficulty in reproducing atmospheric conditions on Jupiter and achieving the high reentry velocity, it might be difficult to achieve similitude in an experiment. Thus, it seems reasonable to simulate this flow with a computational model. It is likely, however, that some experiments will be required because of uncertainties in the CFD model and the high cost of failure.
B. An experimental approach seems appropriate, since it is easy to establish the relevant test conditions. Since driving distances vary with any golfer, however, statistical methods will be required to permit confidence in the experimental results. This suggests the use of a device that simulates a golf swing and strikes the ball in a reproducible manner. A golf ball manufacturer might also decide to do some computational modeling to predict how a change in dimple pattern influences drag, since it will be expensive to manufacture golf balls with a range of dimple patterns. Only the patterns that yield favorable computational results would be manufactured and tested.
C. Aerodynamics is a well-established field of fluid dynamics, and many excellent computational codes for predicting flow over a wing are in routine use. The analysis and design of a new wing shape would be carried out first on the computer with selected experiments to verify certain features of the best new design.
D. One cannot learn about the spread of a toxin in the human respiratory system by exposing volunteers to the toxin, and it may be unethical to carry out such a study in animals. This project appears to be a prime candidate for computational simulation or perhaps an experiment that uses a benign tracer material. Intersubject variability in the structure of the lung must be carefully considered.