[MITgcm-support] Orlanski boundary condition

[Martin Losch]

Hi Estanislao,

as far as I understand, the Orlanski BCs only allow wave energy to leave the domain, but the net flow is zero.
The obcs package has no means of automatically computing outflow dynamically (i.e. make water leave the domain, because it piles up along an open boundary or something like that). With useOBCSBalance you can try to correct your Northern boundary so that it has the same outflow as the inflow at the Southern boundary, like this:
 useOBCSbalance = .TRUE.,
 OBCS_balanceFacN   = 1.,
 OBCS_balanceFacS   = 0.,
See documentation for details.

Martin


> On 6. Sep 2019, at 08:26, Estanislao Gavilan Pascual-Ahuir <dramauh at hotmail.com> wrote:
> 
> Dear community,
> 
> I am no sure how it works this boundary condition. I mean in theory allows waves to leave the domain. Therefore, this can change the flow at the boundary. I have set a small experiment where I open a North and a South boundary.  I prescribe a flow across the south boundary and a set the north boundary with the Orlanski boundary condition. I would have guessed that this produces an outflow across the North boundary but I did not observe that. Do I need to active the useOBCSbalance? Thanks so much in advance fo your help
> 
> Kind regards,
> 
> Estanislao
> 
> data.obcs
> 
> &OBSC_PARAM01
> OBCSfixTopo=.False.,
> OB_Ieast=0,
> OB_Iwest=0,
> OB_Jnorth(29:53)=25-1,
> OB_Jsouth(29:53)=25-1,
> OBSvFile='OBzonalinV05const.bin',
> OBSuFile='OBmeridU05const.bin',
> useOrlanskiNorth=.TRUE.,
> OBCS_monitorFreq=1200.00,
> OBCS_monSelec=1,
> &
> 
> &OBCS_PARAM02
> &
> 
> 
> 
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