空气动力学三大方程- x4 R, B0 M1 l% B- _0 d8 Q" ~
7 w6 ~8 P0 q5 n8 r* H+ _[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题' [/ l, s3 K+ n7 b: l1 t
; H8 P* k* \; `; D# z9 Z6 xthese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
, \) U5 y" q- |& ?3 ?a. Mass is conserved (i.e., mass can be neither created nor destroyed).( h, O) R2 D7 A5 t8 {
b. Newton’s second law: force = mass × acceleration.: x' U& c H+ @
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.- q4 t+ p# m( }0 [) x, B! H G2 ]
这些方程如下:
' \% g; e. }: a+ C4 g% s! S' P1.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 m( N! @: o, p O9 u1.质量是守恒的(即既不能产生质量也不能破坏质量)。8 S D7 p# g: @5 o7 V$ X! c I
2.牛顿第二定律:力=质量×加速度。
. q8 I4 b) u7 X3.节约能源; 它只能从一种形式变为另一种形式。
- X% ]! ?; n, P# _8 Y( q0 `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。( D& d! }9 `# h
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。3 `9 ^3 x8 t& o5 j. z
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