Important Question And Answer: Civil - Fluid Kinematics And Dynamics

1.     Define local acceleration?                 

        It is defined as the rate of increase of velocity with respect to time at a

        given point in a flow field.               

2.     Define convective acceleration?       

It is defined as the rate of change of velocity due to the change of position of fluid particle in a fluid flow.

3.                Define velocity potential function?

It is defined as a scalar function of space and time such that its negative derivative with respect to any direction gives the fluid velocity in that direction. It is denoted by .

U,v,w are the velocity in x,y,z direction.

4.              Mention the properties of potential function?

          1.                          If velocity potential exists, The flow should be irrotational.

          2.                         If velocity potential satisfies the Laplace equation, It represents the possible steady incompressible irrotational flow.

5.            Define stream function

It is defined as the scalar function of space and time, such that its partial derivative with respect to any direction gives the velocity component at right angles to that direction.

6.            Mention the properties of stream function?

         1.                       If stream function exists, it is a possible case of fluid flow which may be rotational.

           2.                       If stream function satisfies Laplace equation, It is a possible case of an irrotational flow.

7.          What is equipotential line?

A line along which the velocity potential is constant is called equipotential line.

8.              Give the relation between stream function and velocity potential function?

9.              What is flow net?

A grid obtained by drawing a series of equipment lines and steam lines is called a flow net. The flow net is an important tool is analysis two dimensional. Irrotational flow problems.

10.      What are the types of motion of fluid particle?

i.                          Linear translation or pure translation

ii.                          Linear Deformation

Angular Deformation

iv.                           Rotation.

11.      What is linear translation?

It is defined as the movement of a fluid element in such a way that it moves bodily from one position to represents in new position by a'b'&c'd' are parallel.

12. What is linear deformation?

It is defined as the deformation of a fluid element in linear direction when the element moves the axes of the element in the deformation position and un deformation position are parallel but their lengths changes.

13. Define rotation of fluid element?

It is defined as the movement of a fluid element in such a way that both of Rotate in same direction. It is equal to1/2( v/ x-u/ y) for a two-dimensional element x, y plane.

x=1/2( w/ y- v/ z) y=1/2( u/ z- w/ x) z=1/2( u/ x- u/ y)

14. Define vortex flow mention its types?

Vortex flow is defined as the flow of a fluid along a curved path or the flow of a rotating mass of fluid is known as vortex flow.

i.                                              Forced vortex flow.

ii.                                            Free vortex flow.

15.         Define free vortex flow?

When no external torque is required to rotate the fluid mass that type of flow Is called free vortex flow.

16. Define forced vortex flow?

Forced vortex flow is defined as that type of vortex flow in which some external Torque is required to rotate the fluid mass. The fluid mass in the type of flow rotates at constant Angular velocity 'w'.The tangential velocity of any fluid particle is given by v=cosr.