Chapter 1 Fluid statics 流体静力学
1. 连续介质假定(Continuum assumption)：The real fluid is considered as no-gap continuous media, called the basic assumption of continuity of fluid, or the continuum hypothesis of fluid. 流体是由连续分布的流体质点(fluid particle)所组成，彼此间无间隙。它是流体力学中最基本的假定，1755年由欧拉提出。在连续性假设之下，表征流体状态的宏观物理量在空间和时间上都是连续分布的，都可以作为空间和时间的函数。
2. 流体质点（Fluid particle）: A fluid element that is small enough with enough moles to make sure that the macroscopic mean density has definite value is defined as a Fluid Particle. 宏观上足够小，微观上足够大。
3. 流体的粘性（Viscosity）: is an internal property of a fluid that offers resistance to shear deformation. It describes a fluid's internal resistance to flow and may be thought as a measure of fluid friction. 流体在运动状态下抵抗剪切变形的性质，称为黏性或粘滞性。它表示流体的内部流动阻力，也可当做一个流体摩擦力量。The viscosity of a gas increas with temperature, the viscosity of a liquid decreas with temperature.
4. 牛顿内摩擦定律（Newton’s law of viscosity）：
5. The 经典文章dynamic viscosity（动力黏度）is also called absolute viscosity（绝对黏度）. The kinematic viscosity（运动黏度）is the ratio of dynamic viscosity to density.
6. Compressibility（压缩性）：As the temperature is constant, the magnitude of compressibility is expresd by coefficient of volume compressibility (体积压缩系数) к , a relative variation rate（相对变化率） of volume per unit pressure.
The bulk modulus of elasticity (体积弹性模量) E is the reciprocal of coefficient of volume compressibilityк.
第三季度工作总结
7. 流体的膨胀性(expansibility; dilatability)安乃近的副作用：The coefficient of cubical expansion (体积热膨胀系数) αt is the relative variation rate of volume per unit temperature change.
8. 表面张力Surface tension: A property resulting from the attractive forces between molecules. -----鲛人泪单位长度所受拉力
9. 表面力 Surface force——is the force exerted on the contact surface by the contacted fluid or other body. Its value is proportional to contact area. 作用在所研究流体外表面上与表面积大小成正比的力。Stress （应力） is the surface force on per unit area.
10. 质量力Mass force——The force acting on every fluid mass particle within the control body. Its value is proportional to its mass. Mass force is also known as body force. 作用在流体的每一个流体质点上，其大小与流体所具有的质量成正比。
11. Euler Equilibrium Equations欧拉平衡微分方程（分量式） 1775年
Physical Meaning:
For the fluid in equilibrium, surface force components per mass fluid are equal to mass force components per mass fluid. Pressure variation rate in axes directions are equal to mass force components per unit volume in axes directions respectively
12. constant-pressure Surface(关于菊花的资料等压面)——a surface that the pressure of every point in liquid is equal. Common constant-pressure surfaces are free liquid surface and interface of two unmixed fluids in equilibrium.平衡流体中压强相等的点所组成的平面或曲面。
次的组词
13. Pressure Distribution in the Static Fluid 重力场中流体的平衡
Conclusions:
1. Pressure at a point in a static fluid under gravity increas linearly with depth.
2. Pressure at a point in a static fluid under gravity is equal to the sum of the pressure at the free surface and the fluid specific weight timing depth.
3. constant-pressure surface in a static fluid under gravity is a horizontal plane.
4. Extended: while the pressure at a point and the depth difference between two points are known, the pressure at another point can be calculated.
14. Absolute pressure(绝对压力), Gage pressure(相对压力, 又称“表压力”), and Vacuum(真空度): 表压力＝绝对压力－大气压力; 真空度＝大气压力－绝对压力
15. Fluid in Relative Equilibrium(相对静止流体) Equation of constant-pressure surface(等压面方程):
a) Uniform Linear Acceleration等加速度直线运动流体:
b) Uniform Rotation about a Vertical Axis等角速度旋转流体:
Chapter 2 basic equations of fluid mechanics
16. 迹线 pathline：the trace after a single particle travels in a field of flow over a period of time. 流体质点的运动轨迹曲线
17. 流线streamline ： a curve that show the direction of a number of particles at the same instant of time.某一时刻处处与速度矢量相切的空间曲线--滑轮瞬时性。
18. Stream-tube(流管)——Consider a clod curve(not streamline) in the flow field, then draw streamlines through every point on it, so as to form a tube-shaping space who walls are streamlines. This tube is called the stream-tube. 关于美好的作文在流场中任
取一个有流体从中通过的封闭曲线，在曲线上的每一个质点都可以引出一条流线，这些流线簇围成的管状曲面称为流管。
19. Tube-flow 流束——Fluid fulling the stream tube is called the tube-flow and the limit of a tube-flow is a streamline. 流管内的全部流体称为流束。
20. Mini stream-tube 微小流束——The stream tube with an infinitesimal ction is said to be mini-stream tube. Streamline is the extreme ca of mini-stream tube. 截面无穷小的流束。
21. Total flow 总流——Total of countless mini-stream tubes is called total flow. 包含流动中所有的微小流束。
22. Cross ction(过水断面)---The ction is perpendicular to the direction of fluid flow. (such as pipe flow and channel flow) 与流束或总流流线 成正交的断面。
