CMS-Flow Model Parameters

From CIRPwiki
Revision as of 23:26, 18 January 2011 by Deleted (talk | contribs) (→‎Hot Start)
Jump to navigation Jump to search
Figure 1. CMS-Flow Model Control : Model Parameters tab in SMS 11.0.

All of the CMS-Flow model parameters, settings, and output options are controlled from the CMS-Flow Model Control window (Figure 1). The window has several tabs including the Flow tab in which most of the general settings are set for CMS-Flow. To open the CMS-Flow Model Control window, click on CMS-Flow | Model Control. The first tab will be the Flow tab. There are several sections within the tab including Time Control and Hot Start options.

Time Control

Below are some of the CMS cards related to the Time Control of the Flow tab. Table 1 provides a brief description of the CMS cards used for time control.

Card Arguments Default Range Description
STARTING_JDATE REAL none none Julian data in YYDDD with YY being last two digits of the year, and DDD the Julian day of the year.
STARTING_JDATE_HOUR REAL none none Julian hour .
HYDRO_TIME_STEP REAL Calculated based on solution scheme and courant number none Sets to the time step for hydrodynamics in seconds.
DURATION_RUN REAL 48.0 >RAMP>0 Sets the duration of the model simulation in hours.
DURATION_RAMP REAL 1.0 Sets the length of the ramp period in which the model forcing is slowly ramped from zero.


Hot Start

CMS Hot Start File

Figure 1. XMDFView showing the structure of the CMS Hot Start File.

The CMS hot start feature CMS lets the user restart simulations that have been stopped due to electric outages, hardware malfunctions, or model crashes. In the case of a model crash the user, may restart the model using larger solver iterations and/or time steps to stabilize the simulation. The user has the option to specify a hot start output time or an interval for outputting a recurring hot start file. Every time the hot start file is written, it overwrites the previous information. The CMS Hot Start file saves information on the water elevation (pressure), and current velocities. If the sediment transport is active, then the water depth, and sediment concentrations are also saved for each size class. The CMS hot start file is a binary XMDF file, has the name Hot_Start.h5 and is saved in the directory of the CMS-Flow files. Figure 1 shows the structure of the hot start file.


User Specified Hot Start File

Figure 2. Dataset Toolbox showing a time step sample of the water elevation and current velocity datasets for use in a hot start (initial condition) file.

There are several situations where it is convenient to specify a user defined hot start file. For example, if the user forgets to setup the model output a hot start file or when running steady state conditions. A hot start file can easily be created and exported by the user from the SMS interface.

Card Arguments Default Range Description
INITIAL_STARTUP_FILE CHARACTER none none Julian data in YYDDD with YY being last two digits of the year, and DDD the Julian day of the year.
HOT_START_OUTPUT_FILE CHARACTER none none Julian hour.
HOT_START_TIME REAL none none Sets the hot start output time.
AUTO_HOT_START_INTERVAL REAL none none Sets the recurring hot start output time.


General Parameters

Card Arguments Default Range Description
WATER_DENSITY REAL none none Julian data in YYDDD with YY being last two digits of the year, and DDD the Julian day of the year.
WATER_TEMPERATURE REAL none none Julian hour .
DRYING_DEPTH REAL Calculated based on solution scheme and courant number none Sets to the time step for hydrodynamics in seconds.
SOLUTION_SCHEME REAL 48.0 >RAMP>0 Sets the duration of the model simulation in hours.
DURATION_RAMP REAL 1.0 Sets the length of the ramp period in which the model forcing is slowly ramped from zero.

Advanced Options

Card Arguments Default Range Description
WATER_PONDING CHARACTER OFF ON | OFF Turns On or Off water ponding. If water ponding is Off, isolated bodies of water will become dry.
ONE_CELL_WIDE_CHANNELS CHARACTER ON ON | OFF Limits wetting and drying to areas with at least 3 cells wide. When turned off, the model stability is improved.
HYDRO_MAX_ITERATIONS INTEGER Function of grid size >0 Sets the maximum number of iterations for the flow (hydro) solver (outer loop).
PRESSURE_ITERATIONS INTEGER Depends on Solver >0 Sets the number of solver iterations for the pressure equation (inner loop).
VELOCITY_ITERATIONS INTEGER Depends on Solver >0 Sets the number of solver iterations for the velocity or momentum equations (inner loop).
MATRIX_SOLVER CHARACTER GMRES GAUSS-SEIDEL | GAUSS-SEIDEL-SOR | BICGSTAB | GMRES Selects the matrix solver for flow, sediment and salinity.
ADVECTION_SCHEME CHARACTER EXPONENTIAL NONE | HYBRID | EXPONENTIAL | HLPA Sets the advection scheme for flow, sediment and salinity.



Documentation Portal