空气动力学三大方程6 @+ w" l% x7 k+ K# h6 _
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[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题) ~( Y8 |- d5 g
/ W. S, s' L# f7 sthese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
8 j; z! L' w* O I- k# fa. Mass is conserved (i.e., mass can be neither created nor destroyed).
7 w# B8 ]& L, y$ O1 K5 Tb. Newton’s second law: force = mass × acceleration.2 C9 `. _9 H) D/ @
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$ |% I/ ]4 k+ x1 g- Y/ b
这些方程如下:6 |1 I# Z6 {6 o3 ~" s
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
; W& y! M0 g9 g4 b9 s0 I, m. e1.质量是守恒的(即既不能产生质量也不能破坏质量)。
: W& H1 m! u8 A2.牛顿第二定律:力=质量×加速度。
: \2 T6 F8 f+ T3.节约能源; 它只能从一种形式变为另一种形式。7 V, r; W6 Q; h- _% i
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。
* {* l0 y7 M* ]1 M& p: O3.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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