CMS-Flow:Ripple Dimensions

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The bed forms calculated by CMS are the wave- and current-related ripples. The ripple height (used to calculate the mixing layer thickness) is estimated as the maximum of the current- and wave-related ripple heights


The current-related ripple height and length are calculated as (Soulsby 1997)


The wave-related ripple height and length are calculated using the expressions proposed by van Rijn (1984b, 1989):



Aw = semi-orbital excurision =
= wave mobility parameter =
d50 = median grain size [m]
s = sediment specific gravity [-]
g = gravitational constant (9.81 m/s2)
uw = bottom orbital velocity [m/s] (for random waves
T = wave period [s] (for random waves T = Tp).

The current- and wave-related ripple height and length are used in calculating the bed form roughness for use in the Lund-CIRP transport formula.


  • Soulsby, R. L. 1997. Dynamics of marine sands. London, England: Thomas Telford Publications.
  • van Rijn, L. C. 1984b. Sediment transport, Part II: Suspended-load transport. Journal of Hydraulic Engineering, ASCE 110(11):1613–1641.
  • van Rijn, L. C. 1989. Handbook: Sediment transport by currents and waves. Delft, The Netherlands: Delft Hydraulics.

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