sediment initial conditions for median grain diameter

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undave
Posts: 10
Joined: Mon Jul 16, 2007 5:30 pm
Location: Florida Gulf Coast University

sediment initial conditions for median grain diameter

#1 Post by undave » Fri Feb 08, 2019 2:05 pm

I am trying to put together an initial conditions file for a sediment run and using the sediment_test case as an example. A few things I am confused about. In the sediment.in file, SAND_SD50 == 0.25d0, and MUD_SD50 == 0.25d0 , apparently in units of mm. In test_head_ini.nc, the grain_diameter is 0.3019 for every value. How is this median sediment grain diameter determined? Also, in the test_head_ini.nc file, the units for median sediment grain diameter is 'meter', should that be millimeters?
Also, the test_head_ini.nc file contains the variables sand01, sandfrac_01, and sandmass_01, but not the corresponding variables for the mud class. Why is that?

I could not find a matlab example for creating the initial conditions for sediment, the only relevant files I could find in ROMSMatlab directory are c_initial.m and d_initial.m. Are there some examples that would help guide me?

jcwarner
Posts: 798
Joined: Wed Dec 31, 2003 6:16 pm
Location: USGS, USA

Re: sediment initial conditions for median grain diameter

#2 Post by jcwarner » Tue Feb 12, 2019 1:03 am

if you are serious about using the sediment capabilities, i suggest you use our coawst system. we have added more capabilities such as a more advanced bed load formulation, a floc model, and a faster positive definite advection scheme. we distribute m files for init conditions. you can send me an email to jcwarner@usgs.gov.

the shorter answer is that in the sediment.in files, the values are entered as mm
"! Median sediment grain diameter (mm).
SAND_SD50 == 0.25d0"

For test_head_ini.nc, i have not updated that case in a long time and not sure where that 0.319 is from. The nc file lists the units as meters and those units are ok but that value of .319 seems to not be ok. The values read from the sediment.in file in mm are multiplied by 1000 before written to a netcdf file.

"The test_head_ini.nc file contains the variables sand01, sandfrac_01, and sandmass_01, but not the corresponding variables for the mud class. Why is that?" - that is because the test case only activates sand
" NCS = 0 ! Number of cohesive (mud) sediment tracers
NNS = 1 ! Number of non-cohesive (sand) sediment tracers"

undave
Posts: 10
Joined: Mon Jul 16, 2007 5:30 pm
Location: Florida Gulf Coast University

Re: sediment initial conditions for median grain diameter

#3 Post by undave » Tue Feb 12, 2019 2:24 pm

OK, Thanks for your response
David

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