units

1) Kinematic viscosity= Kinematic Viscosity is the ratio of absolute (dynamic) viscosity to density ( mass density ) of a fluid.

Kinematic Viscosity(ν)=µ/ ρ

Kinematic Viscosity(v)= (m^2/s) and it is also expressed in stokes, where 1 stoke= (10^-4 m^2/s)

2) Dynamic Viscosity= Dynamic Viscosity is the ratio of shear stress to rate of strain (Velocity Gradient) .

Dynamic Viscosity (μ)= [ (τ)/ (du/dy)]

Dynamic Viscosity (μ)=( N s/ m^2) and alternatively it is also expressed as (Pa.s)

3) Paclet Number= It is the ratio of product of charactaristic length and velocity to the dispersion. it is also defined as the ratio of thermal energy convected to the fluid to the thermal energy conducted within the fluid.

Paclet Number ( Pe) = [(L) × (Vx)/ D]

It is the dimensionless number.

4) Nusselt Number= It is the ratio of convective to conductive heat transfer across ( normal to) the boundary.

Nusselt Number (Nu)=[ (h A ΔT)/ (- k A ΔT/L)]= hL/k

substituting the units, Nusselt number is a dimensionless number.

5) Momentum Flux= Rate of change of horizontal momentum which is moving across a unit area, equal to force per unit area.

Momentum Flux= Force/Area

Unit- N/m^2

6) Fourier\'s law of heat conduction= Rate of heat transfer through a uniform material is proportional to the area, the temperature drop and inversely proportional to the length of the path of flow.

Q= -kA (dT/dx) and its unit is W ( Watt).

7)Fick\'s law of diffusion= Flux over some finite thickness can be measured using this law.

flux is proportional to concentration gradient.

J ∝(dC/dx)

J=-D(dC/dx), where D is diffusion constant.

Unit= [mass/ (unit area)×( unit time) ]

8) Wall shear stress= It is the product of dynamic viscosity and velocity gradient at wall start.

τ =[ μ ×(∂u/∂y) ]at y=0

SI unit is Pa, which is identical to (kg/ms^2)

9) Gradient of temperature field= It is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location.

T= T(x,y,z)

then gradient of temperature field is given as, ∇T= (∂T/ ∂x,∂T/ ∂y,∂T/ ∂z)

SI Unit= kelvin/meter (K/m)

10) Divergence of velocity field= considering a velocity field as V( x,y,z)

Divergence of a velocity field is gives as ∇·V= (∂Vx/∂x, ∂Vy/∂y, ∂Vz/∂z)

Unit= [mass/ ( unit volume) ×(unit time)]