[MITgcm-support] MITgcm-support Digest, Vol 91, Issue 4
Matthew Mazloff
mmazloff at ucsd.edu
Thu Jan 13 13:43:34 EST 2011
Hi Chunyun,
By default the sponge layer will be on both sides. You will need to
do a little code modifying to only have the sponge on the west. It
may not be too hard though...
-Matt
On Jan 13, 2011, at 10:32 AM, Chun-Yan Zhou wrote:
> Dear Matthew,
> Thanks for your replying. But I still feel confused about the
> "spongeThickness=15,"
> from the above code, how can I know where the sponge layer is? for
> example, I want put a sponge at the west boundary between i=1 and
> i=15, the spongeThickness=15. However, Could you tell me how to
> assure the sponge layer is in the west instead of in the east?
> Many thanks!
>
> chunyan
>
>
>
>
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> 1. Re: How to use OBCS and add the Sponges layer? (Matthew Mazloff)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 13 Jan 2011 10:13:41 -0800
> From: Matthew Mazloff <mmazloff at ucsd.edu>
> To: "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
> Subject: Re: [MITgcm-support] How to use OBCS and add the Sponges
> layer?
> Message-ID: <7EC739BF-8D85-4133-8167-764378125731 at ucsd.edu>
> Content-Type: text/plain; charset="utf-8"; Format="flowed";
> DelSp="yes"
>
> Hi Chunyan
>
>
> Mostly fine...although I don't know of anyone who has used Orlanski or
> obcs balance succesfully so as a first start you may want to turn
> these off and then experiment with them later...so try:
>
> > C This include hooks to the Orlanski Open Boundary Radiation code
> > #undef ALLOW_ORLANSKI
> >
> > C balance barotropic velocity
> > #undef ALLOW_OBCS_BALANCE
>
>
> and then of course
> > useOrlanskiEast=.FLASE.,
> > useOBCSbalance=.FALSE.,
>
>
> Also I would use
> useOBCSprescribe=.TRUE.,
> not sure if "1" works
>
> and also, you give
> > OBEuFile = 'OBzonalU.bin',
> but you also need to give
> > OBWuFile = 'OBzonalU.bin',
>
>
> As for PARM03 put something like:
> &OBCS_PARM03
> Urelaxobcsinner=864000.E0,
> Urelaxobcsbound=43200.E0,
> Vrelaxobcsinner=864000.E0,
> Vrelaxobcsbound=43200.E0,
> spongeThickness=15,
> &
>
> and I would recommend give V,T,and S too -- even if they are trivial
>
> Hope that is everything and not too confusing,
> Matt
>
>
>
>
>
> On Jan 13, 2011, at 1:58 AM, Chun-Yan Zhou wrote:
>
> > Dear all,
> >
> > I am trying to do quite a simple configuration: The model domain
> > covers a continental slope and neighbouring parts of the deep ocean
> > and shelf. A barotropic tidal flow into the model domain from the
> > east open boundary (2D problem, no y-dependency, no Coriolis). My
> > basin is 300km across and I use dx=500m and dz=100*25m (i.e. grid
> > dimensions is 600x1x100).
> > Furthermore, I want to add a sponge-layer (50 Km width) at the
> > lateral boundary of the deep ocean (the west boundary) to absorb the
> > baroclinic ?elds.
> > I have read the OBCS package in the manual and the examples but
> > still can not understand well.
> > OBCS_OPTIONS.h
> > #include "CPP_OPTIONS.h"
> >
> > #ifdef ALLOW_OBCS
> >
> > C Enable individual open boundaries
> > #undef ALLOW_OBCS_NORTH
> > #undef ALLOW_OBCS_SOUTH
> > #define ALLOW_OBCS_EAST
> > #define ALLOW_OBCS_WEST
> >
> > C This include hooks to the Orlanski Open Boundary Radiation code
> > #define ALLOW_ORLANSKI
> >
> > C Enable OB values to be prescribed via external fields that are
> read
> > C from a file
> > #define ALLOW_OBCS_PRESCRIBE
> >
> > C This includes hooks to sponge layer treatment of uvel, vvel
> > #define ALLOW_OBCS_SPONGE
> >
> > C balance barotropic velocity
> > #define ALLOW_OBCS_BALANCE
> >
> > C The following five CPP options are experimental and aim to
> deal
> > C with artifacts due to the low-frequency specification of sea-
> ice
> > C boundary conditions compared to the model forcing frequency.
> > C Ice convergence at edges can cause model to blow up. The
> > C following CPP option fixes this problem at the expense of less
> > C accurate boundary conditions.
> > #undef OBCS_SEAICE_AVOID_CONVERGENCE
> >
> > C Smooth the component of sea-ice velocity perpendicular to the
> > edge.
> > #undef OBCS_SEAICE_SMOOTH_UVICE_PERP
> >
> > C Smooth the component of sea ice velocity parallel to the edge.
> > #undef OBCS_SEAICE_SMOOTH_UVICE_PAR
> >
> > C Smooth the tracer sea-ice variables near the edges.
> > #undef OBCS_SEAICE_SMOOTH_EDGE
> >
> > C Compute rather than specify seaice velocities at the edges.
> > #undef OBCS_SEAICE_COMPUTE_UVICE
> >
> > #endif /* ALLOW_OBCS */
> > #endif /* OBCS_OPTIONS_H */
> >
> >
> > Data.obcs
> > # Open-boundaries
> > &OBCS_PARM01
> > OB_Ieast=600*1, ( is this right?)
> > OB_Iwest=1*1, ( is this right?)
> > useOrlanskiEast=.TRUE.,
> > useOBCSbalance=.TRUE.,
> > useOBCSsponge=.TRUE.,
> > #
> > useOBCSprescribe=1,
> > #
> > OBEuFile = 'OBzonalU.bin',
> > &
> >
> > # Orlanski parameters
> > &OBCS_PARM02
> > Cmax=0.45,
> > cVelTimeScale=1000.,
> > &
> >
> > # Sponge-layer parameters
> > &OBCS_PARM03
> > spongeThickness=100,
> > Urelaxobcsinner = long relaxation time scale of your choice,
> > Urelaxobcsbound= short relaxation time scale,(is there any method
> > to give these two parameters?)
> > spongeThickness = # grid points,( how to describe the sponges
> > position between (1,1 and 100,1)? )
> >
> > &
> >
> > I am appreciate any help/advices; if you need more info let me know.
> > Thanks in advance.
> > Chunyan
> >
> >
> > Chunyan Zhou
> > Division of Civil Engineering
> > School of Engineering, Physics and Mathematics
> > College of Art, Science and Engineering
> > Fulton Building
> > University of Dundee
> > Dundee DD1 4HN
> >
> >
> >
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