Wave orbital velocities and wave induced bottom friction

[smrhashemi]

Hello All

Referring to this page, https://www.myroms.org/wiki/index.php/SSW_BBL
I think, there might be a mistake in the equation for computing the wave orbital velocities ub=Hs/(2sinh(kh)), at least the dimensions are not consistent. The relationship in linear wave theory [1] is ub=pi*H/(Tsinh(kh)), I would be grateful if you can clarify that.

In the ROMS discussion (viewtopic.php?f=14&t=3150), it has been said that it is possible to use variable friction factor (e.g drag coefficient), I was wondering, if there is a test case which has applied the variable friction? This could be used when someone wants to apply a wave induced friction without SWAN-ROMS coupling.

Thanks

[1] Wiberg, P. L. and C. R. Sherwood, 2008: Calculating wave-generated bottom orbital velocity from surfacewave parameters. Computers & Geosciences, 34, 1243-1262.

[jcwarner]

seems like it has
Ub(i,j)=Fwave_bot(i,j)*Ab(i,j)+eps
and using
Fwave_bot(i,j)=twopi/MAX(Pwave_bot(i,j),0.05_r8)
Ab(i,j)=0.5_r8*Hwave(i,j)/SINH(Kbh)+eps
we get
Ub(i,j)=twopi/Pwave_bot(i,j)*0.5_r8*Hwave(i,j)/SINH(Kbh)+eps
Ub(i,j)=pi/Pwave_bot(i,j)*Hwave(i,j)/SINH(Kbh)+eps
so i think that is ok.

for var friction- have not used that yet but will test it soon.
-j

[smrhashemi]

thanks John,
that was very helpful.