Other Processes

Eddy Viscosity

Eddy Viscosity in CMS-Flow is not a user definable parameter. A description of the advanced cards related to eddy viscosity is shown in the table below.

Card	Arguments	Default	Range	Description	Versions
TURBULENCE_MODEL	CHARACTER	SUBGRID	SUBGRID \|FALCONER\| PARABOLIC \| MIXING-LENGTH	Specifies the turbulence model used	>=3.5
EDDY_VISCOSITY_CONSTANT	REAL	1.0E-6	>=1.0E-6	Constant contribution or base value of eddy viscosity	>=3.5
EDDY_VISCOSITY_BOTTOM	REAL	0.0667	0.01-0.2	Coefficient related to the contribution to eddy viscosity from the bottom shear	>=3.5
EDDY_VISCOSITY_HORIZONTAL	REAL	0.4	0.2-0.6	Coefficient related to the contribution to eddy viscosity from horizontal velocity gradients	>=3.5
EDDY_VISCOSITY_WAVE	REAL	0.5	0.2-1.0	Coefficient related to the wave bottom friction contribution to eddy viscosity	>=4.0
EDDY_VISCOSITY_BREAKING	REAL	0.05	0.04-0.08	Coefficient related to the wave breaking contribution to eddy viscosity	>=4.0

More information can be found here.

Other Features

Parallelization with OpenMP

Both Intel and AMD processors now are shipping chips with multiple cores/processors (henceforth referred to as "processors") available. CMS-Flow is now configured to make use of these extra processes that are available on newer machines.

Additional information on using Multiple Processors with CMS-Flow can be found here.

Advanced Output

The following advanced cards have been added to CMS v4.0 and higher for outputting additional output information, ASCII file output, and more.

Card	Arguments	Description	Default value
XMDF_COMPRESSION	ON \| OFF	Compresses the h5 file by a factor of about 7	OFF
WAVE_OUT_TIMES_LIST	integer	Output time series id	0
EDDY_OUT_TIMES_LIST	integer	Output time series id	0
VISC_OUT_TIMES_LIST	integer	Output time series id	0
STRESS_OUT_TIMES_LIST	integer	Output time series id	0
BED_SHEAR_STRESS_OUT_TIMES_LIST	integer	Output time series id	0
GLOBAL_TECPLOT_FILES	ON \| OFF	Outputs Tecplot ASCII files	OFF
GLOBAL_SUPER_FILES	ON \| OFF	Outputs Tecplot ASCII files	OFF
GLOBAL_STATISTICS	[t0] [tn] [dt]	Calculates global statistics if specified	none
FLOW_STATISTICS	[t0] [tn] [dt]	Calculates flow statistics if specified	none
SEDIMENT_STATISTICS	[t0] [tn] [dt]	Calculates sediment statistics if specified	none
SALINITY_STATISTICS	[t0] [tn] [dt]	Calculates salinity statistics if specified	none

Matrix solver

The four different solvers implemented in the implicit model are the Gauss-Seidel, Gauss-Seidel with Successive-Over-Relaxation, BICGSTAB, and GMRES. The same solver is applied to flow, sediment and salinity. The default solver is the GMRES. The solver may be changed using the advanced card in the table below.

Card	Arguments	Description	Default value
SOLVER_TYPE	GAUSS-SEIDEL \| GAUSS-SEIDEL-SOR \| BICGSTAB \| GMRES	Determines the numerical solver used	GMRES
HYDRO_MAX_ITER	integer	Maximum number of iterations (outer loop) for the hydrodynamics	20
SEDIMENT_MAX_ITER	integer	Maximum number of iterations (outer loop) for the sediment transport	20
SALINITY_MAX_ITER	integer	Maximum number of iterations (outer loop) for the salinity transport	20

Advection scheme

As in the case of the solver, the same advection scheme is applied for the flow, sediment and salinity transport equations. There are three choices for advection schemes with upwinding in the implicit model: hybrid, exponential and HLPA. The hybrid scheme is fast but is the most diffusive. The exponential scheme is based on the 1D analytical solution to an advection-diffusion equation and produces very stable results. The HLPA is very stable and non-diffusive, but requires slightly more computational time. For most applications, the exponential scheme is recommended and is set as the default. The advection scheme may be change using the advanced card

Card	Arguments	Description	Default value
ADVECTION_SCHEME	HYBRID \| EXPONENTIAL \| HLPA	Determines the advection scheme	EXPONENTIAL

Units of Measurement

Variable	Units	Symbol
Water Surface Elevation	meters	$m$
Current Velocity	meters per second	$m/sec$
Flow Rate	cubic meters per second	$m^{3}/sec$
Salinity Concentration	parts per thousand	$ppt$
Sediment Concentration	kilogram per meter cubed	$kg/m^{3}$
Sediment Transport	meter squared per second	$m^{2}/sec$
Bed Shear Stress	kilogram per meter per second squared	$Pa$