Fluid Mechanics: Kinematics of Fluid Flows

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Questions and Answers

What does kinematics primarily focus on?

The pressure distribution in stationary fluids

The forces causing motion

The energy transformations in a fluid

The motion of particles without considering forces (correct)

Which statement best describes a stream line?

An imaginary line indicating the direction of velocity vector (correct)

A curve traced by a fluid particle during its motion

A line that connects all particles in a fluid at rest

A fixed path followed by all fluid particles in steady flow

How is the time taken by a fluid particle to move a distance 'ds' along a stream line expressed?

t = ds^2/Vs

t = ds/Vs (correct)

t = Vs/ds

t = (dx + dy + dz)/Vs

What delineates a path line in fluid dynamics?

The locus of a fluid particle as it moves Signup and view all the answers

In unsteady flow, what happens to fluid particles in relation to stream lines?

Fluid particles may change to other stream lines Signup and view all the answers

What is a streak line in fluid dynamics?

The line connecting particles passing through a given point Signup and view all the answers

What defines an instantaneous stream line?

A line that is fixed in space during time-independent flow Signup and view all the answers

Which of the following relationships is correct for a fluid particle moving along a stream line?

dx/u = dy/v = ds/Vs Signup and view all the answers

What is defined as a boundary surface across which fluid cannot penetrate?

Stream tube Signup and view all the answers

In which type of flow does the velocity, pressure, and density at a point change with respect to time?

Unsteady flow Signup and view all the answers

Which type of fluid flow is characterized by smooth and parallel movement of fluid particles?

Laminar flow Signup and view all the answers

What does the Reynolds number indicate in fluid flow?

Type of flow (laminar or turbulent) Signup and view all the answers

What is the defining characteristic of compressible flow?

Density changes from point to point Signup and view all the answers

Which type of flow is assumed to be one-dimensional?

Flow with negligible variation in two perpendicular directions Signup and view all the answers

What is the unit of discharge (Q) for liquids?

m3/sec or Litres/sec Signup and view all the answers

Which flow type does not permit any rotation of fluid particles during flow?

Ir-rotational flow Signup and view all the answers

Which property describes steady flow?

Velocity, pressure, and density remain constant at a point Signup and view all the answers

What describes two-dimensional flow?

Velocity is a function of time with negligible variation in z direction Signup and view all the answers

Study Notes

Kinematics of Fluid Flows

Kinematics studies fluid motion without considering the forces causing it.
Knowing velocity allows determining pressure distribution and forces on the fluid.

Streamlines

A streamline is an imaginary line with a tangent representing velocity direction at each point.
No flow occurs across a streamline.
The differential equation for a streamline is: dx/u = dy/v = dz/w, where u, v, and w are velocity components.

Path Lines

A path line is the trajectory of a single fluid particle.
It connects the positions of a particle over time.
Streamlines and path lines may differ in unsteady flow.

Streak Lines

A streak line shows the paths of all fluid particles passing through a fixed point.
Dye or smoke traces out streak lines.
In steady flow, streamlines, path lines, and streak lines coincide.

Instantaneous Streamlines

In time-dependent flow, streamlines change with time.
An instantaneous streamline represents the position of a streamline at a specific instant.

Stream Tubes

Streamlines forming a closed curve create a stream tube.
Fluid cannot cross stream tube boundaries.
The amount of fluid entering a stream tube equals the amount leaving.

Flow Classifications

Steady vs. Unsteady:
- Steady flow: Fluid properties (velocity, pressure, density) remain constant with time at a specific point.
- Unsteady flow: Fluid properties change with time at a specific point.
Uniform vs. Non-uniform:
- Uniform: Velocity stays constant with respect to space (direction).
- Non-uniform: Velocity changes with respect to space.
Laminar vs. Turbulent:
- Laminar: Fluid particles move in smooth, parallel layers (streamlines).
- Turbulent: Fluid particles move in a chaotic, irregular manner, creating eddies. Reynolds number (VD/v) helps determine flow type.
Compressible vs. Incompressible:
- Compressible: Fluid density changes with flow.
- Incompressible: Fluid density remains constant. Liquids are typically incompressible.
Rotational vs. Irrotational:
- Rotational: Fluid particles rotate about their axes as they flow.
- Irrotational: Fluid particles do not rotate.
One, Two, and Three-Dimensional Flows:
- One-dimensional: Flow parameters vary with one spatial coordinate.
- Two-dimensional: Flow parameters vary with two spatial coordinates.
- Three-dimensional: Flow parameters vary with three spatial coordinates.

Discharge (Rate of Flow)

Discharge (Q) is the volumetric flow rate per unit time.
For liquids, units are m³/s or L/s.
For gases, units are kgf/s or N/s.

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Description

Explore the fundamental concepts of fluid flow kinematics in this quiz. Understanding streamlines, path lines, and streak lines will deepen your knowledge of fluid motion and behavior. Test your comprehension of key principles such as velocity and pressure distribution.