上游充通大学 Shanghai Jiao Tong University 第四章 流体静力学 流体静力学是研究船舶浮性、 稳性、抗沉性的主要理论基础
Shanghai Jiao Tong University 第四章 流体静力学 流体静力学是研究船舶浮性、 稳性、抗沉性的主要理论基础
浒充通大￥ 4.1 Shanghai Jiao Tong University Indroduction to Hydrostatics M GM W G C F B W B Water Water H Hinge 6m Hinge R 3m
Shanghai Jiao Tong University 4.1 Indroduction to Hydrostatics
上浒充通大￥ 4.1 Indroduction to Hydrostatics Shanghai Jiao Tong University Hydrostatics is the study of pressures throughout a fluid at rest and the pressure forces on finite surfaces. As the fluid is at rest,there are no shear stresses in it.Hence the pressure at a point on a plane surface always acts normal to the surface,and all forces are independent of viscosity. The pressure variation is due only to the weight of the fluid. (a) (b) (c)
Shanghai Jiao Tong University 4.1 Indroduction to Hydrostatics Hydrostatics is the study of pressures throughout a fluid at rest and the pressure forces on finite surfaces. As the fluid is at rest, there are no shear stresses in it. Hence the pressure at a point on a plane surface always acts normal to the surface, and all forces are independent of viscosity. The pressure variation is due only to the weight of the fluid
上浒充通大￥ 4.2 Indroduction to Pressure Shanghai Jiao Tong University Pressure always acts inward normal Pressure to any surface. Body Pressure is a normal stress,and hence has dimensions of force per unit area,or [ML-1T-2]. In the Metric system of units,pressure is expressed as "pascals"(Pa)or N/m2. △Fn Standard atmospheric pressure is 101.3 kPa. Surface Pressure is formally defined to be △A lim △Fn △A→0△A where AF is the normal compressive force acting on an infinitesimal area4
Shanghai Jiao Tong University 4.2 Indroduction to Pressure Pressure always acts inward normal to any surface. Pressure is a normal stress, and hence has dimensions of force per unit area, or [ML-1T-2]. In the Metric system of units, pressure is expressed as "pascals" (Pa) or N/m2. Standard atmospheric pressure is 101.3 kPa. 0 lim n A F p Δ → A Δ = Δ Pressure is formally defined to be where ΔF n is the normal compressive force acting on an infinitesimal area . ΔA
上浒充通大￥ 4.3 Pressure at a Point Shanghai Jiao Tong University By considering the equilibrium of a small triangular wedge of fluid extracted from a static fluid body,one can show that for any wedge angle the pressures on the three faces of the wedge are equal in magnitude: ps=py=p: independent of 0 This result is known as Pascal's law,which states that the pressure ,6r6 at a point in a fluid at rest,or in motion,is independent of direction 6 as long as there are no shear stresses present. y 2
Shanghai Jiao Tong University 4.3 Pressure at a Point By considering the equilibrium of a small triangular wedge of fluid extracted from a static fluid body, one can show that for any wedge angle θ, the pressures on the three faces of the wedge are equal in magnitude: independent of syz ppp = = θ This result is known as Pascal's law, which states that the pressure at a point in a fluid at rest, or in motion, is independent of direction as long as there are no shear stresses present