Computes Diameter given Discharge, Material, and Head Loss using Swamee Jain (1976)

D = Pipe diameter (in feet or meters)

Q = Discharge (in ft^3/sec or m^3/sec)

g = Gravitational acceleration constant (32.2 ft/s^2 or 9.8 m/s^2)

hl = Head loss (in feet or meters)

L = Pipe length (feet or meters)

ks = Equivalent sand roughness height (a material property; in feet or meters)

v = Kinematic viscosity (in feet^2/second or meter^2/second)

Notes:

Swamee and Jain, A. K., 1976. Explicit equations for pipe-flow problems.

ASCE J. of Hyd. Div., 102(HY5) pp. 657-664