空气动力学三大方程
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. Q( V2 {% {! y Y7 `$ I: p[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题% u- S( }2 y1 @6 T) Z
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these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
6 R0 y, J2 N( L( ^' s* Ca. Mass is conserved (i.e., mass can be neither created nor destroyed).% R3 H+ }1 b( ~2 g- W
b. Newton’s second law: force = mass × acceleration.. m; ^7 x9 [9 e/ 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.
* U3 W+ p3 C, F这些方程如下:5 r# @0 y; R& G# \; r% n4 ~, 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0 r' s6 P3 k' y3 ?( M# `$ T
1.质量是守恒的(即既不能产生质量也不能破坏质量)。8 V5 i: n% x( U+ q: a
2.牛顿第二定律:力=质量×加速度。
$ M! W' H2 H- E- z+ y* V w) A, W# w3.节约能源; 它只能从一种形式变为另一种形式。; r" v7 y$ _4 {: u( @. [5 ?- k
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。: Z9 \& q3 G: \6 v8 h! P
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。1 `/ F! R; c0 W4 S
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