Experiment as an Aid to Improved Modelling
Boundary-layer theory was developed when Prandtl observed in wind tunnel experiments that velocity gradients were confined to a small layer close to the solid wall. In recent years, laboratory experiments have revealed the existence of coherent structures even in relatively continuous flows; an example is shown in Figure 1.1 for a mixing-layer. The wave-like structures of Figure 1.1 increase the amount of entrainment and substantially increase heat transfer.
Figure 1.1: Schematic Drawing of a Mixing-layer |
These examples show that experiments can bring to light unknown and unexpected phenomena and lead to the development of new theories.
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