Isothermal Pipe Flow Calculator

Isothermal Pipe Flow Equation

$$ p_2 = p_1 \sqrt{1 - \frac{4f {u_1}^2 L}{R T d} - \frac{2 {u_1}^2}{RT} ln \left(\frac{p_1}{p_2}\right) } $$ where:

p₂ = Pressure at point 2 (Pa)

p₁ = Pressure at point 1 (Pa)

f = Darcy-Weisbach friction factor (dimensionless)

u₁ = Average fluid velocity (m/s²)

L = Length of pipe (m)

R = Specific gas constant (j/kgK)

T = Absolute temperature (K)

d = Diameter of the pipe (m)

Calculator

Property to Calculate:

This is an iterative technique (enter some initial value for p2).

Pressure at point 2 (p₂):

Pressure at point 1 (p₁):

Darcy-Weisbach friction factor (f):

Average fluid velocity (u₁):

Length of pipe (L):

Specific gas constant (R):

Absolute temperature (T):

Diameter of the pipe (d):

Equation Assumptions

The fluid is incompressible and Newtonian.
The fluid is in a steady flow.
The fluid flow is laminar.
The cross-section is uniform.
There is no heat transfer.
The pipe is ideal (i.e., there is no friction from roughness or imperfections).