Civil - Mechanics Of Fluids - Fluid Properties And Fluid Statics
FLUID PROPERTIES AND FLUID STATICS
1. Define fluids.
Fluid may be defined as a substance which is capable of flowing. It has no definite shape of its own, but confirms to the shape of the containing vessel.
2. What are the properties of ideal fluid? Ideal fluids have following
i) It is incompressible
ii) It has zero viscosity
iii) Shear force is zero
3. What are the properties of real fluid? Real fluids have following
i) It is compressible
ii) They are viscous in nature
iii) Shear force exists always in such fluids.
4. Define density and specific weight.
Density is defined as mass per unit volume (kg/m3)
Specific weight is defined as weight possessed per unit volume (N/m3) 5. Define Specific volume and Specific Gravity.
Specific volume is defined as volume of fluid occupied by unit mass
(m3/kg) Specific gravity is defined as the ratio of specific weight of fluid to the specific weight of standard fluid.
6. Define Surface tension and Capillarity.
Surface tension is due to the force of cohesion between the liquid particles at the free surface.
Capillary is a phenomenon of rise or fall of liquid surface relative to the adjacent general level of liquid.
7. Define Viscosity.
It is defined as the property of a liquid due to which it offers resistance to the movement of one layer of liquid over another adjacent layer.
8. Define kinematic viscosity.
It is defined as the ratio of dynamic viscosity to mass density. (m²/sec)
9. Define Relative or Specific viscosity.
It is the ratio of dynamic viscosity of fluid to dynamic viscosity of water at 20°C.
10. Define Compressibility.
It is the property by virtue of which fluids undergoes a change in volume under the action of external pressure.
11. Define Newtonian law of Viscosity.
According to Newton’s law of viscosity the shear force F acting between two layers of fluid is proportional to the difference in their velocities du
and area A of the plate and inversely proportional to the distance between them.
12. What is cohesion and adhesion in fluids?
Cohesion is due to the force of attraction between the molecules of the same liquid.
Adhesion is due to the force of attraction between the molecules of two different liquids or between the molecules of the liquid and molecules of the solid boundary surface.
13. State momentum of momentum equation?
It states that the resulting torque acting on a rotating fluid is equal to the rate of change of moment of momentum
14. What is momentum equation
It is based on the law of conservation of momentum or on the momentum principle It states that,the net force acting on a fluid mass is equal to the change in momentum of flow per unit time in that direction.