空气动力学三大方程* h- u; {/ X; J. H9 c! y3 L
# E* I. h5 k8 w: n9 ]8 s0 M[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题. i/ y& V8 B2 q; a9 n1 J3 J0 a
" c, O U& v' k9 ?$ Bthese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
6 r) Q( T ]" _ \6 Za. Mass is conserved (i.e., mass can be neither created nor destroyed).) c5 o" y: i d0 B( \% S
b. Newton’s second law: force = mass × acceleration.- H' R1 Z3 G; [0 a& ~7 l* Q; ^
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- s* h1 e1 L9 J/ i# z) E5 X这些方程如下:- Y) ^* \2 i" `$ `1 w( a1 q
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
1 k# z( ]. t- u: V" [7 q1.质量是守恒的(即既不能产生质量也不能破坏质量)。8 m5 D/ ]4 S1 i" b' c! a
2.牛顿第二定律:力=质量×加速度。% p' c% n3 _8 ?
3.节约能源; 它只能从一种形式变为另一种形式。/ f1 L9 ~, I+ C
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。 Z& G+ D) v! ` h# x
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。
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