空气动力学三大方程$ i# m: |4 J0 g/ U- I1 i& i
! J l' L& Z9 K[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题" L2 C+ p. _! z- W2 } s6 F
9 a- C% y8 K! N- X2 n# P3 T% Vthese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,+ U8 t1 H) z6 e* G. _
a. Mass is conserved (i.e., mass can be neither created nor destroyed).' ]7 E: ?9 ]# y) v2 N, c; B* Z
b. Newton’s second law: force = mass × acceleration.+ b; r' p) d V4 N. X5 l# X& j% v
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.7 P& {9 a( @* ?& ], o
这些方程如下:4 P: s( [- |% s, U$ _4 J
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9 c) g; W' w% c1 K% X2 i
1.质量是守恒的(即既不能产生质量也不能破坏质量)。
2 {, q5 b* x6 G# Z! J1 D/ c3 K' p8 V2.牛顿第二定律:力=质量×加速度。! u3 G ?" _5 N
3.节约能源; 它只能从一种形式变为另一种形式。
- i% q8 k/ Q1 d5 f9 }9 X2 {7 s! Z2.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。
j o7 m; X4 \( Y3.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。* @3 x, e& ~! O1 [" j; m
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