The three types of similarities are, 1. Geometric similarity 2. Kinematic similarity 3. Dynamic similarity
Similitude
The
three types of similarities are,
1. Geometric
similarity
2. Kinematic
similarity
3. Dynamic
similarity
Scale ratio.
Scale
ratio is the ratio of linear dimension in the model and prototype which are
equal in a geometric similarity. It is denoted by Lr.
Lr
= Lp/Lm = bp/bm = Dp/Dm
Dynamic similarity.
It
means the similarity of forces at corresponding points in the model and
prototype is equal.
Types of forces in a moving fluid.
The
types of forces in a moving fluid are,
1. Inertia
force (fi)
2. Viscous
force (fv)
3. Gravity
force (Fg)
4. Pressure
force (Fp)
5. surface
tension (Fs)
6. Elastic
force (Fe)
Dimensionless numbers.
Dimensionless numbers are the numbers
obtained by dividing inertia force or gravity force or pressure force or
elastic force or surface tension. They are called as non-dimensional
parameters.
Surface tension.
Surface
tension force is defined as the product of surface tension and length of
surface of flowing fluid.
Pressure force.
Pressure force is the product of pressure
intensity and cross-sectional area of the flowing fluid in case of pipe flow.
Elastic force.
Elastic force is defined as the product of
elastic stress and the area of flowing fluid.
Types of dimensionless numbers.
The
types of dimensionless numbers are:
1. Reynold's
number
2. Froude's
number
3. Euler's
number
4. Weber's
number
5. Mach's
number
Reynold's number.
Reynold's
number is defined as the ratio of inertia force of flowing fluid and viscous
force of the fluid. It is denoted by (Re)
Re
= V x d / v = ? V d / ?
Froude's number
Froude's
number is defined as square root of ratio of inertia force of flowing fluid to gravity. It is denoted as Fe