Understanding Aerodynamics: Arguing from the Real Physics

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Introduction to the Conceptual Landscape

The objective of this book is to promote a solid physical understanding of aerodynamics. In general, any understanding of physical phenomena requires conceptual models:

It seems that the human mind has first to construct forms independently before we can find them in things. Kepler's marvelous achievement is a particularly fine example of the truth that knowledge cannot spring from experience alone but only from the comparison of the inventions of the intellect with observed fact.

— Albert Einstein on Kepler's discovery that planetary orbits are ellipses

Einstein wasn't an aerodynamicist, but the above quote applies as well to our field as to his. To understand the physical world in the modern scientific sense, or to make the kinds of quantitative calculations needed in engineering practice, requires conceptual models. Even the most comprehensive set of observations or experimental data is largely useless without a conceptual framework to hang it on.

In fluid mechanics and aerodynamics, I see the conceptual framework as consisting of four major components:

1. Basic physical conservation laws expressed as equations and an understanding of the cause-and-effect relationships those laws represent,
2. Phenomenological knowledge of flow patterns that occur in various situations,
3. Theoretical models based on simplifying the basic equations and/or assuming an idealized model for the structure of the flowfield, consistent with the phenomenology of ...