空气动力学三大方程' b" @' S B" ^! @2 ~0 N
- V# S1 r9 g4 z. j[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题
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these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
7 x( V; p- U7 Ka. Mass is conserved (i.e., mass can be neither created nor destroyed).
8 ?5 s! K& q8 v- jb. Newton’s second law: force = mass × acceleration.3 g' [7 M J. \1 Y# j8 Z w
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./ A% F1 {4 a6 V5 @) u/ X
这些方程如下:5 F: B$ e7 B, R
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
" ^8 V/ o' U* {/ I5 j( E6 w1.质量是守恒的(即既不能产生质量也不能破坏质量)。2 Q& @* ]' J& I
2.牛顿第二定律:力=质量×加速度。1 w4 F; `- K6 z2 g7 b- c5 U
3.节约能源; 它只能从一种形式变为另一种形式。3 O+ P. L2 @3 E# k9 }# N
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。+ C& e! t# f9 ^4 o
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。/ }$ d* `4 L; R" q# }3 D" I
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