Units of Quantities

Units of Quantities

1. Kinematic viscosity- Defined as the ratio of the viscosity to the density.

` v=μρv=μρ where μμ - dynamic viscosity & ρρ- density

Units :- m^2/s.

2. Dynamic Viscosity- The force that is required to overcome internal friction in a fluid.

u=τγu=τγ where ττ = shearing stress in fluid & γγ = shear rate.

Units :- Ns/m^2.

3. Peclet Number- It is defined as the ratio of the rate of the advection of a physical quantity by the flow rate of diffusion of the same quantity driven by the correct gradient. It is also defined as the product of Reynold number and Prandtl number. i.e. Pe=Re.PrPe=Re.Pr

>> Re.Pr=LuαPe=Re.Pr=L where L- characteristics of length u- velocity αα- thermal diffusivity.

4. Nusselt Number- It is the ratio of convective to conductive heat transfer in a particular fluid over a given length.

>> Nu=h.l/k where, h = Heat transfer coefficient l = characteristic length. k = Thermal conductivity.

5. Momentum flux- It is the rate of change of momentum flowing through a unit area.