u and u_stokes & zeta and zeta_w clarification

General scientific issues regarding ROMS

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samuel.rickerich
Posts: 6
Joined: Thu Oct 01, 2020 4:01 pm
Location: University of Maine at Orono

u and u_stokes & zeta and zeta_w clarification

#1 Unread post by samuel.rickerich »

Hi,

I am running a coupled ROMS-SWAN application on an idealized domain that includes the VF formalism to incorporate the wave-effect on currents, similar to the 'inlet_test' application distributed with COAWST. I am interested in understanding how overtides in current velocities and the free surface are modified by waves (the model is forced with an M2 tide).

In the history files I write both u and u_stokes, v and v_stokes, and zeta and zeta_w. The roms_in.in file defines them as:

Hout(idUvel) == T ! u 3D U-velocity
Hout(idVvel) == T ! v 3D V-velocity
Hout(idU3Sd) == T ! u_stokes 3D U-Stokes velocity
Hout(idV3Sd) == T ! v_stokes 3D V-Stokes velocity
Hout(idFsur) == T ! zeta free-surface
Hout(idWztw) == T ! zetaw WEC_VF quasi-static sea level adjustment

However, I am not sure if these variables are written to the history file as they are defined in Kumar et al (2012). In the history file, does u = u_e + u_stokes, v = v_e + v_stokes, and zeta_c = zeta + zeta_w (where 'u_e' is a Eulerian mean velocity and 'zeta_c' is the composite sea level)?

Or would I have add the 3D velocity to the 3D stokes velocity to obtain the 'composite velocity' and add zeta to zeta_w to obatian the 'composite free surface'?

I did my best to investigate the .f90 scripts to answer this question, but I am not confident in my understanding of them. Thank you for your time and consideration.

Regards,
Sam

jcwarner
Posts: 1172
Joined: Wed Dec 31, 2003 6:16 pm
Location: USGS, USA

Re: u and u_stokes & zeta and zeta_w clarification

#2 Unread post by jcwarner »

this was a discussion point, and we decided to always have u- v- ubar- vbar be Eulerian.
then we also can write out u_stokes, v_stokes, ubar_stokes, vbar_stokes.
the lagrangian would then be eulerian + stokes.

"In the history file, does u = u_e + u_stokes, v = v_e + v_stokes, and zeta_c = zeta + zeta_w (where 'u_e' is a Eulerian mean velocity and 'zeta_c' is the composite sea level)?"
NO. they his file has the terms separate, u in his is u eulerian. u_stokes in his is u stokes.

Or would I have add the 3D velocity to the 3D stokes velocity to obtain the 'composite velocity' and add zeta to zeta_w to obatian the 'composite free surface'?
YES.

samuel.rickerich
Posts: 6
Joined: Thu Oct 01, 2020 4:01 pm
Location: University of Maine at Orono

Re: u and u_stokes & zeta and zeta_w clarification

#3 Unread post by samuel.rickerich »

Hi John,

Thank you for your reply and clarification, I appreciate it. I am glad I asked!

Thanks again,
Sam

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