空气动力学三大方程1 l, h0 B3 X+ c' G9 s) M
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[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题# J/ }' w- O1 V7 V: R
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these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
5 x2 Z2 X8 [) q5 y ?3 L; Ja. Mass is conserved (i.e., mass can be neither created nor destroyed).
1 ?: s. a* A8 p/ A& `" wb. Newton’s second law: force = mass × acceleration.1 e8 ^( n% K' D2 o y) q
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.
1 m( V# p$ R" h" Z$ q' J8 H h这些方程如下:0 b! q( f/ ^+ e/ R; Y1 B+ b
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
% [; F# f7 H3 S. S' G6 e/ |1.质量是守恒的(即既不能产生质量也不能破坏质量)。
/ o, U* D" k( r5 o2.牛顿第二定律:力=质量×加速度。
+ [5 k- e+ u3 }7 a4 }4 ^3.节约能源; 它只能从一种形式变为另一种形式。: W1 u# z4 y8 G4 ?, ?
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。: P5 u8 _* W) A6 O: w
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。
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