Create a sponge layer

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matias.dinapoli
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Create a sponge layer

#1 Unread post by matias.dinapoli »

Hello, I'm trying to set a sponge layer in the western and eastern edge. So I modified ana_sponge:

Code: Select all

        width=20.0_r8                !20 == 200 km

        MIXING(ng) % visc2_r(IstrT:IendT,JstrT:JendT)=0.0_r8
        MIXING(ng) % visc2_p(IstrT:IendT,JstrT:JendT)=0.0_r8
!
!  Eastern edge.
!
      DO i=MAX(IstrT,Lm(ng)+1-INT(width)),IendT
        DO j=JstrT,JendT
          MIXING(ng) % visc2_r(i,j)=50.0_r8
          MIXING(ng) % visc2_p(i,j)=50.0_r8
        END DO
      END DO
and in ocean.in:

Code: Select all

VISC2 == 0.0d0                           ! m2/s
VISC4 == 0.0d0                           ! m4/s

    LuvSponge == T                              ! horizontal momentum
LtracerSponge == F F                            ! temperature, salinity, inert
But, I compare the fields with and with out sponge, and I get the same results. I didn't set visc2 because I fix its value for each grid point in ana_sponge. Is there any option to see the value of the viscosity at each point? To check that ROMS do I what I want.

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arango
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Re: Create a sponge layer

#2 Unread post by arango »

I did a major overhaul of the sponge areas in ROMS sometime ago. We can have now visc_factor and diff_factor in the Grid NetCDF file. This is the way all application (simple or complex) that require areas of enhanced viscosity and diffusion. See the following :arrow: trac ticket for details. Notice that you can plot this new NetCDF variables and check the distribution of the sponge areas.

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kate
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Re: Create a sponge layer

#3 Unread post by kate »

There is currently no code to write out the 2- or 3-D visc variables. For this sort of check, I would run it in the debugger and query the variables at run time. Others would stick in a print statement.

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wilkin
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Re: Create a sponge layer

#4 Unread post by wilkin »

One thing to check is analytical.f90 in your Build directory to see if your code was actually activated before compiling.

You do have UV_VIS2 defined, and one of MIX_S_UV or MIX_GEO_UV, right?
John Wilkin: DMCS Rutgers University
71 Dudley Rd, New Brunswick, NJ 08901-8521, USA. ph: 609-630-0559 jwilkin@rutgers.edu

matias.dinapoli
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Re: Create a sponge layer

#5 Unread post by matias.dinapoli »

Hello, my problem was that my model is barotropic, so the flux wasn't affected by a low viscosity. I incremeted the value to 5000 and this worked. I think that more efficient, in my case, is to use nudgings options.

Thanks!

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kate
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Re: Create a sponge layer

#6 Unread post by kate »

If you're trying to damp things out, the model responds well to increasing the bottom drag. Just be sure to turn the limiter on to avoid instabilities.

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