空气动力学三大方程7 Y) q" f$ v( ~! i9 \ _
9 l; N& P5 r9 R6 L- f! H" c[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题# z2 R; T% o. Z+ _1 ^0 W6 K
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these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,7 u8 p+ r1 I/ q V6 t% X7 i
a. Mass is conserved (i.e., mass can be neither created nor destroyed).
9 Q2 y6 v; C! y* Z4 O. gb. Newton’s second law: force = mass × acceleration.! R: l" X5 |' |5 {+ r2 B& o
c. Energy is conserved; it can only change from one form to another. - Determine a suitable model of the fluid. Remember that a fluid is a squishy substance, and therefore it is usually more difficult to describe than a well-defined solid body. Hence, we have to adopt a reasonable model of the fluid to which we can apply the fundamental principles stated in item 1.
- Apply the fundamental physical principles listed in item 1 to the model of the fluid determined in item 2 in order to obtain mathematical equations which properly describe the physics of the flow. In turn, use these fundamental equations to analyze any particular aerodynamic flow problem of interest. J" f: q# N% k: |$ i
这些方程如下:' O. ?+ c- ?% I1 K1 Y
1.引用我们对自然的宏观观察中根深蒂固的三个基本物理原则,即
8 ^; S8 D& Y6 `& Q1.质量是守恒的(即既不能产生质量也不能破坏质量)。" F4 t$ o/ _4 Q5 g' O
2.牛顿第二定律:力=质量×加速度。3 x: ^: U9 s/ h7 O( a: S" J c
3.节约能源; 它只能从一种形式变为另一种形式。 W4 y* h) [% |9 C! H% I! I n
2.确定合适的流体模型。 请记住,流体是一种柔软的物质,因此通常比明确定义的固体更难描述。 因此,我们必须采用合理的流体模型,我们可以应用第1项所述的基本原则。' s8 e( P2 X* T6 M
3.将第1项中列出的基本物理原理应用于第2项中确定的流体模型,以获得正确描述流动物理学的数学方程。 反过来,使用这些基本方程来分析任何感兴趣的特定空气动力学流动问题。; k. H* D7 b( M. V; \& c& s
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