# Equation used in Wave Speed Calculator tool

 Product(s): HAMMER Version(s): CONNECT Edition, V8i Area: Calculations

# Problem

What equation does HAMMER use to calculate Wave Speed in the Wave Speed Calculator Tool?

# Solution

HAMMER uses the following equation developed by Korteweg. This is generally considered valid for thin-walled pipelines (D/e > 40) so if your pipe is not thin-walled (for example HDPE pipes may be too thick) or if you do not want to use the Korteweg equation, use another method such as ModelBuilder import as described here: Entering Pipe Wave Speed for a Transient Simulation

Where:

a = Wave speed (ft/s, m/s)
Ev = Bulk modulus of Elasticity (lbf/ft^2, Pa)
p = liquid density (slugs/ft^3, kg/m^3)
D = Diameter (in, mm)
e = wall thickness (in, mm)
E = Young's Modulus (lbf/ft^2 / Pa)
ψ = pipeline support factor (see below)

• Pipe is anchored throughout against axial movement: ψ = 1 - µ 2 , where µ is Poisson's ratio
• Pipe is equipped with functioning expansion joints throughout: ψ = 1 - µ/2
• Pipe is supported only at one end and allowed to undergo stress and strain both laterally and longitudinally: ψ = 5/4 - µ (ASCE, 1975)