[MITgcm-support] oscillating mean flow

[Matthew Mazloff]

Hi Mark,

If you have a prescribed constant inflow and outflow on east/west  
boundaries a pressure gradient will be set up to allow this mean zonal  
jet -- the rotation you see may be a spin-up issue -- or maybe the  
oscillation causes it to go unstable

i would set up the mean flow first and run to equilibrium -- then  
initialize with this state when you add your oscillation.

-Matt




On Jun 10, 2010, at 8:33 AM, Mark Inall wrote:

> Hi,
> Thanks Jody and thanks Samar.
>
> Samar, I think you just have an oscillating flow with zero mean - is  
> that right? I wasn't too clear in my posting, but I want to try to  
> add a non-zero mean flow on top of the oscillating component.
>
> Jody, I tried adding a constant mean flow at the boundaries. This  
> worked fine with f=0: the non-zero U BCs propagated into the domain  
> at the barotropic phase speed. But with rotation, the imposed U- 
> momentum wants to rotate, and then there's a mismatch between the N  
> and S boundaries (at least that's what I think happens) ... that's  
> why I wondered about imposing a cross slice pressure gradient (or  
> moving to a channel with walls) - but I'm not sure how to do that ....
>
> Mark.
>
>>>> Samar Khatiwala <spk at ldeo.columbia.edu> 10 June 2010 16:00 >>>
> Hi Mark,
>
> Yes, this has been done many times, for e.g., see here: http://www.ldeo.columbia.edu/~spk/Papers/KhatiwalaInternalTidesDSR03.pdf
>
> This is a bit dated, but I know others have implemented it in more  
> recent versions of the code.
>
> Samar
>
> On Jun 10, 2010, at 10:16 AM, Mark Inall wrote:
>
>> Hi,
>>
>> Does anyone have experience with setting up an oscillating mean  
>> flow - either in 2D or in a narrow channel - with rotation?
>>
>> Presently I'm running an oscillating flow over a bump based on the  
>> internal wave verification setup, and I want to add a mean flow -  
>> is the best way to impose a barotropic pressure gradient across the  
>> section and wait for a geostrophic balance??
>>
>> Any thoughts/help much appreciated.
>>
>> Thanks,
>>
>> Mark.
>>
>>
>>
>>
>> Dr Mark Inall
>> Reader in Marine Physics
>> Scottish Association for Marine Science
>> Scottish Marine Institute
>> Oban PA37 1QA
>>
>> E: mei at sams.ac.uk
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