Henry Darcy : is a French hydraulic engineer interested in purifying water supplies using sand filters, conducted experiments to determine the flow rate of water through the filters.

Julius Ludwig Weisbach : was a German mathematician and engineer.He also refined the Darcy equation into the still widely used Darcy-Weisbach equation.

Pressure Drop (Darcy Law) :

This darcy law is basis for all modern analysis of ground water and used to figure out the relationship between the fluid viscosity and the presssure drop over a given distance.Pressure Drop (Darcy Law) is calculated as follows:

Q = -kA (P_b - P_a)μL

Where,

k - Soil coefficient of permeability (m²)

A - Cross section area of flow (m²)

P_a - Final presure (p_a)

P_b - Initial Presure (p_a)

μ - Viscosity (p_a)

L - Length (m)

Q - total discharge in m³/s

Permeability is a property of the porous medium that measures the capacity and ability of the formation to transmit fluids.

Pressure Loss (Darcy-Weisbach Equation) :

This equauion is used to find the fluid pressure loss due to friction along a given length of pipe to the average velocity of fluid flow for an incompressible fluid.

Δp = f_D ^. LD ^. pV²2

Where,

Δp - Pressure Loss in N/m²

f_D - Darcy friction factor

L - Length of the pipe (m)

D - Hydraulic diameter (m)

V - Average velocity of the fluid flow (m/s)

p - Fluid density( kg/m³ )

Head Loss (Darcy-Weisbach Equation) :

Darcy-Weisbach equation is an empirical equation, which relates the head loss along a given length of pipe to the average velocity of the fluid flow for an incompressible fluid.The below equation is named after Henry Darcy and Julius Weisbach.

h_f = f_D ^. LD ^. V²2g

Where,

h_f - Head Loss (m)

f_D - Darcy friction factor

L - Length of the pipe (m)

D - Hydraulic diameter (m)

V - Average velocity of the fluid flow (m/s)

g - Standard Gravity ( g = 9.80665 m/s² )