Recovering From Errors During Simulation

In most cases, the source of the error will have been written out to the log file generated during your MIKE 21 ST simulation. In order to recover from the error, follow the steps below.

1.       Inspect the MIKE 21 ST log file that has been created in your work direc­tory to check at what stage of the calculation the error occurred. The log file can be inspected using any text editor such as Notepad.

2.       Inspect the MIKE 21 ST specification file for possible errors. The log file will give you an indication of what to check. The specification file can also be inspected using any text editor.

3.       Run the sediment transport simulation again. If the problem persists, repeat steps 1 and 2 above until it has been solved.

In most cases, the problem will be related to the fact that the axes of the sed­iment transport table(s) do not cover the whole range of variation of the parameters involved when calculating sediment transport under combined waves and current.

You can try to solve the problem by extending the sediment transport table(s). You can either use the tool for Extension of sediment tables (if you chose to use the 2DH version of the STP program to calculate the transport rates) or the tool for Extension of Q3D sediment tables (if you chose to use the Q3D version of the STP program).

You can also use the facility for limiting the value of the relevant parameters within the Simulation Area (p. 50) to the minimum and/or maximum values along the corresponding axes of the sediment transport table(s). In order to do this, the options in Table 5.1 below can be used. The required option parameters have to be defined in the OPTION_PARAMETERS section of the specification file for your MIKE 21 ST run.

By default, all parameters are internally set to 0, implying that an error mes­sage will be generated and the simulation will be stopped if the limits of the transport table are exceeded. You can change the defaults for some or all of the parameters to 1, and thus limit the parameter values for calculating sedi­ment transport to the limits in the table.

Table 5.1             Option parameters for avoiding search beyond the limits of the sedi­ment transport table

Option parameter (limit minimum)

Option parameter (limit maximum)

Limit_min_V

Limit_max_V

Limit_min_HoD

Limit_max_HoD

Limit_min_H

Limit_max_H

Limit_min_T

Limit_max_T

Limit_min_Sg

Limit_max_Sg

Limit_min_d50

Limit_max_d50

Limit_min_dddx

Limit_max_dddx

Limit_min_dddy

Limit_max_dddy

Limit_min_gam

Limit_max_gam

This facility should be used with utmost caution, since your sediment trans­port calculations will not be accurate beyond the limiting values of the param­eters. Unless results have to be achieved for a quick preliminary assessment, it is always advisable to extend the sediment transport table(s).