空气动力学三大方程- _+ Q3 d8 y& s* A0 q/ z. n7 q/ K
7 T& u6 D( e' P2 p: t. c1 B[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题- w+ c) s% N2 k3 X& f
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these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
& J( m0 J6 W+ \, w0 ra. Mass is conserved (i.e., mass can be neither created nor destroyed).* g" N( t/ u' f$ S, C9 n" i" j
b. Newton’s second law: force = mass × acceleration.2 e' Y/ s9 ^. H3 s
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.
" ^4 x2 q+ w" e" f+ K9 S这些方程如下:
, B9 H9 e& G3 j* J) }# u! w: X1.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
s1 q4 U8 \9 R# @7 B1.质量是守恒的(即既不能产生质量也不能破坏质量)。# |3 Y; ~, L- Z% ^
2.牛顿第二定律:力=质量×加速度。8 ?- h, f& n9 x4 V
3.节约能源; 它只能从一种形式变为另一种形式。
" C: ]) `1 Y/ ~+ D4 O5 s# u6 q2.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。
/ }: F; u3 `/ n) o8 v3.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。& s3 |+ J9 K( Q; Q' n# Y. r
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