CMS-Flow:Ripple Dimensions: Difference between revisions

From CIRPwiki
Jump to navigation Jump to search
No edit summary
No edit summary
Line 18: Line 18:
\end{align} \right.</math>|4}}
\end{align} \right.</math>|4}}


{{Equation|<math>
L_{r,w} = \left\{\begin{align}
&1.25 A_w \quad \quad for \ \psi_w < 10 \\
&1.4 \ x \ 10^{-6}(250 - \psi_w)^{2.5} \quad for \ 10 \leq \psi_w < 250\\
&0 \quad \quad \quad \quad for \ 250 \leq \psi_w\end{align}
\right.</math>|5}}
where:
: A<sub>w</sub> = semi-orbital excurision = <math>\frac{u_w T}{2 \pi} [m/s]</math>
:<math>\psi_w</math> = wave mobility parameter = <math> \frac{u_w ^2}{(s-1)gd_{50}}[-]</math>
:d<sub>50</sub> = median grain size [m]
:s sediment specific gravity [-]
:g = gravitational constant (9.81 m/s<sup>2</sup>)
:u<sub>w</sub> = bottom orbital velocity [m/s] (for random waves u<sub>w</sub> = <math>\sqrt{2} u_{rms})</math>
:T = wave period [s] (for random waves T = T<sub>p</sub>).
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.


= References =
= References =

Revision as of 20:05, 27 October 2014

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

  (1)

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

  (2)
  (3)

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

  (4)
  (5)

where:

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 uw =
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.

References


Documentation Portal