空气动力学三大方程' b1 \) T' n" c6 }: R
( [: j8 b1 L+ ~$ }( u6 n4 ?; K
[color=rgba(0, 0, 0, 0.74902)]这里写自定义目录标题$ i3 }7 w3 h/ E4 y0 [
4 e0 b+ H U" \; ^8 E
these equations, as follows: - Invoke three fundamental physical principles that are deeply entrenched in our macroscopic observations of nature, namely,
: ?, V8 {+ y; k. E Z: O: Z' Ba. Mass is conserved (i.e., mass can be neither created nor destroyed).# i' ^- Z$ J0 p- y) }# G8 x
b. Newton’s second law: force = mass × acceleration.
; }& M0 }: o6 K, ^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.9 C. H: k3 _% \
这些方程如下:
/ @ j" l2 v) e1 f# J& l5 e1.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1 m' I( j. j: f# Y8 w4 g% W+ ~1 J+ [
1.质量是守恒的(即既不能产生质量也不能破坏质量)。
l3 t$ c. G3 S) R3 x, m/ v2.牛顿第二定律:力=质量×加速度。; O, T+ q9 a( I2 |+ @# v% C1 J1 G. i
3.节约能源; 它只能从一种形式变为另一种形式。
+ T1 t4 `( M# I& g) m4 O8 [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。
: d0 w% E5 C3 c& b3.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。3 X6 W" x" t6 v: Y# R1 I
: b. b2 E7 m5 o, H5 T |