空气动力学三大方程
$ |- x6 V1 f0 S- b
8 W9 D5 i' L, g& j[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题2 o% z& j8 q" c/ B; o$ {
8 Z+ w3 l, ?, H6 k! Gthese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
b+ M v: N7 x6 c+ Y# s2 r8 sa. Mass is conserved (i.e., mass can be neither created nor destroyed).
0 O6 n; ?7 r# [; \b. Newton’s second law: force = mass × acceleration.& ^0 B6 U" B' q+ f. T9 b
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.
5 p: E; D9 O# j; c这些方程如下:/ K, j6 V7 H3 s( q" E
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
6 u+ O3 s, e4 y, B0 H$ K; g1.质量是守恒的(即既不能产生质量也不能破坏质量)。
6 o4 }: w |4 e7 J% R' F5 b2.牛顿第二定律:力=质量×加速度。
5 J. d+ O" v- ]2 L, l3.节约能源; 它只能从一种形式变为另一种形式。
* G& e( W& l% {, t- P/ I2.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。
1 E8 g* X' B D# ?& i3.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。
! C e, ]% `% `" F
. Q5 w: _( j$ r# K |