Relatio between flow and diameter?

Question

Relatio between flow and diameter?

Answer 1

flow rises with square of diameter

Answer 2

Flow is volume/time

Q = V/t

Volume = cross sectional area (pi* r^2) * L

Therefore:

Q = pi*r^2 * L / t

(radius = 0.5*diameter)

Answer 3

The simple answer that the rate of flow is proportional to the cross sectional area of the pipe involved (that is to its diameter squared), but this is not exact.

Depending on the viscosity of the fluid (gas or liquid), a thin layer of it on the inner walls (called the boundary layer) will make the smaller sized pipes (or tubes) less able than this proportion, to supply the necessary flow.

Relatively smaller sizes therefore need to be larger than the size for a larger flow.However the exact details are too complicated to describe here and you will need to refer to the literature dealing with pipe flow.