Dimensional Analysis

Question 1

What is the formula for pressure loss through a pipe?

Answer 1

h= (4flu^2)/(2gtd)

h= pressure loss head (meters)

f=friction faction for the pipe

l=length of pipe (m)

u=velocity of fluid flow (m/s)

g=gravity (9.81m/s^2)

Question 2

How do you calculate the volume flow rate of fluid through an orifice?

Answer 2

V = C_dA(2gh)^-2

V = volume m^3

C_d = dimensionless coefficient

G = Gravity (9.81m/s²)

H=pressure drop head (m)

Question 3

Explain the Reynolds number (Re)

Answer 3

It is a dimensionless number that indicates how laminar or turbulent fluid flow is.

A reynolds number less that 2000 is laminar and number greater that 3500 is turbulent. Anything inbetween is transitional.

Reynolds number is calculated as the ratio of intertial forces to viscous forces

Question 4

Explain the Grashof number (Gr)

Answer 4

Grashof number is the ration of buoyancy forces to viscous forces in natural convection.

Question 5

Explain the Nusselt number (Nu)

Answer 5

Nusselt number relates to forced convection heat transfer.

Heat transfer between the fluid and a surface happens through conduction through the boundary layer and mass transfer through the boundary layer.