空气动力学三大方程9 J2 w# l: s# E( e4 b
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[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题
- J: ~ a+ ~. R d7 I7 e- y+ Q Q+ Q) Y
these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
1 b- {7 B! n9 x% E4 X# ga. Mass is conserved (i.e., mass can be neither created nor destroyed).
% T# Q8 T. g u! D8 wb. Newton’s second law: force = mass × acceleration.
! ? a6 [% V/ Y8 ], W2 _7 P2 O5 Sc. 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.
( L% V9 d' h1 S这些方程如下:
' G* ~% ^8 W4 J& h1.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
' Z+ I* N0 R3 c4 }4 c x7 L1.质量是守恒的(即既不能产生质量也不能破坏质量)。
& W) V7 P* h; g& I2.牛顿第二定律:力=质量×加速度。
8 @$ S6 G1 n3 A3.节约能源; 它只能从一种形式变为另一种形式。. X/ A6 Y6 H3 l1 ^3 Z3 ~" R
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。
: {" T, J' y5 R# s1 H3.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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