Morison Equation Calculator

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Estimate wave-induced forces on slender submerged objects like offshore piles.

Fluid & Geometry Data

Fluid Density (ρ) [kg/m³]

Structure Diameter (D) [m]

Drag Coeff. (Cd)

Inertia Coeff. (Cm)

Instantaneous Velocity (u) [m/s]

Fluid Acceleration (u̇) [m/s²]

Results

Enter velocity and fluid acceleration

About this calculator

Overview

The Morison equation is a cornerstone of offshore engineering. It calculates the total wave force on a pile by summing a velocity-dependent drag force and an acceleration-dependent inertia force. It is valid for 'slender' structures where the diameter is small compared to the wavelength.

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Pro Tips

Sea water density is typically around 1025 kg/m³.
The inertia coefficient (Cm) accounts for the 'added mass' of the fluid being displaced.
Slenderness is defined as a diameter-to-wavelength ratio D/L < 0.2.

Fun Facts

"The Morison equation was developed by a team at UC Berkeley in 1950 and remains the industry standard for oil rig design."
"It assumes the object does not significantly affect the wave field (diffraction is ignored)."
"For very large structures like bridge piers, MacCamy-Fuchs diffraction theory is used instead of the Morison equation."

Formula: F = ½ρCdD u|u| + ρCm(πD²/4) u̇