[MITgcm-support] 回复： Bottom drag setup question

[钱钰坤]

Hi Yilang,


Not so sure but my understanding is that if you set no_slip_bottom=.FALSE., then the drag
coefficient should make no effect on the velocity field (whatever you set).  So the velocity gradient
normal to the bottom boundary should be zero.  In this case, bottom friction does not contribute
to kinetic energy dissipation.  Only viscosity you set in the model, along with numerical dissipation,
contributes to the energy dissipation.


------------------
 Best regards 
 
Yu-Kun Qian (钱钰坤) 
Center for Monsoon and Environment Research 
 Department of Atmospheric Sciences
School of Environmental Science and Engineering 
 Sun Yat-sen University 
No. 135 Xingang West Road, Haizhu District 
Guangzhou, 510275, P.R. China 
Tel; 020-84115227 
Email: qianyk at mail3.sysu.edu.cn      


 
 
 
------------------ 原始邮件 ------------------
发件人: "Yilang Xu"<yxu at whoi.edu>;
发送时间: 2019年6月5日(星期三) 上午10:33
收件人: "mitgcm-support"<mitgcm-support at mitgcm.org>; 

主题: Re: [MITgcm-support] Bottom drag setup question

 


I just checked sideDragFactor setup in mom_v_sidedrag.F, scenario 2 is solved for no slip side. 

Now I mostly wonder the logic behind scenario 1, for the case with free-slip bottom and a specified bottom drag. 

Any clarification is appreciated. 

 

Best,

Yilang

 

From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of Yilang Xu <yxu at whoi.edu>
Reply-To: <mitgcm-support at mitgcm.org>
Date: Tuesday, June 4, 2019 at 22:12
To: "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
Subject: [MITgcm-support] Bottom drag setup question


 


Hi, 

 

I am checking the behavior of the bottom drag, following the old post http://mailman.mitgcm.org/pipermail/mitgcm-support/2011-June/007258.html . 

My question involves 2 scenarios, and I am wondering if my interpretation is right. 

 

1. Scenario 1 setup: 

no_slip_sides=.FALSE.,

no_slip_bottom=.FALSE.,

bottomDragQuadratic=2.5E-3,

Although both the bottom and the side are free slip, there are still bottom friction and energy dissipation at the bottom. I saw some papers do this using MITgcm, but it is not very intuitive to me. 

 

2. Scenarios 2 setup: 

no_slip_sides=.TRUE.,

no_slip_bottom=.TRUE.,

bottomDragQuadratic=2.5E-3,

Now the bottom is no slip with a bottom drag coefficient specified. However, since the side is no slip as well, is there also a drag coefficient that can be specified for the sides? 

 

There are some explanations in the documentation http://mitgcm.org/public/r2_manual/latest/online_documents/node58.html , but I am hoping further clarifications about this. 

 

Thanks,

Yilang

 

_______________________________________________ MITgcm-support mailing list MITgcm-support at mitgcm.org http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20190605/5d17fcd1/attachment.html>