空气动力学三大方程
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[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题
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) G- l C, |; @7 othese equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
) i# y ?# S/ V# da. Mass is conserved (i.e., mass can be neither created nor destroyed).
4 K. G+ p0 b9 lb. Newton’s second law: force = mass × acceleration.8 c( m' Q: h5 o& o
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.
; l# W6 [ z! e1 {& J这些方程如下:
5 f& N! C+ l% b" ?' J0 D1.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
5 B+ W( f- A+ ]6 ~, A0 L1.质量是守恒的(即既不能产生质量也不能破坏质量)。
' V. r: _3 O7 E- a1 G9 S0 V- A! z2.牛顿第二定律:力=质量×加速度。
. {: B, A2 n/ X3.节约能源; 它只能从一种形式变为另一种形式。 ]6 ]; u, W& b" H5 Y+ P6 J: T
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。 g- T! N" S) i, n, U6 Q
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。; `$ n" m' W4 a l' g
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