A small question about sediment.in

[Rocky_Wang]

Hello Everyone，

I have some small questions when use COAWST model to design a mixed bed.

First,I want to konw the what is the unit of the parameter MUD_TAUCR_TIME. Is it days or time steps?

MUD_TAUCR_TIME == 28800.0d0 ! Tau_crit consolidation rate

and the Swelling time scale is order 100 times slower than MUD_TAUCR_TIME ?

Second, when I turn on the MIXED_BED CPP options in .h file, a variable called
bed_tau_crit is needed in the initial file, but I can't find it in his or avg file, I want to know which Logical switches to activate writing of bed_tau_crit into AVERAGE or HISTORY output file.

Thanks ！

[Rocky_Wang]

If the dmix_offset dmix_slope and dmix_time in initial file are used to describe the initial critical shear stress profile; and the MUD_TAUCR_SLOPE MUD_TAUCR_OFF and MUD_TAUCR_TIME in sediment.in are used to describe critical shear stress equilibrium profile?

[Chang]

hello Rocky_Wang
I also graduated from OUC and now i have some same problems with you when i run the ROMS.so could i have your e-mail or other comunication tools? My qq number is 2454518664.Thanks in advance!

[aretxabaleta]

MUD_TAUCR_TIME == 28800.0d0 is in seconds (as the rest of the model). That value implies a consolidation nudging time scale (tendency toward equilibrium critical stress profile) of 8 hours. As the Swelling time scale is 100 times slower, then swelling is order 800 hours in your simulation.

bed_tau_crit in the initial condition file is an average bed value and currently it is not output in the model.

The instantaneous bulk (per bed layer not sediment class) critical shear stress profile is nudged over the time scale Tc or Ts toward the equilibrium profile to represent the effects of consolidation or swelling, respectively, following perturbations caused by erosion or deposition. Tc is the time scale for consolidation, which applies when the instantaneous profile is more erodible than the equilibrium value, and Ts is the time scale for swelling, which applies when the instantaneous profile is less erodible than the equilibrium value. The consolidation time scale is usually chosen to be much shorter than the one associated with swelling (Sanford, 2008).

Please, if you have any questions regarding the cohesive sediment module in COAWST you can ask me directly (aaretxabaleta at usgs dot gov) or ask Chris Sherwood.