HGSYSTEM SCENARIOS; RUNNING MODELS IN SEQUENCE
4.1. HGSYSTEM scenarios
There are two important situations in which information generated by one HGSYSTEM module will be used by a second (subsequent) module:
- Physical properties for a multi-compound mixture, generated by DATAPROP, must be passed on to an HGSYSTEM module using this information in its thermodynamical calculations.
- Models are run in sequence to simulate a complete scenario. A scenario in this context is a complete simulation of a release/near-field/far-field dispersion event. This situation can of course include the above mentioned use of DATAPROP to generate physical properties.
In HGSYSTEM the following scenarios are currently available:
(DATAPROP ) SPILL AEROPLUME HEGADAS or PGPLUME
For liquid releases from a pressurised vessel with a near-field jet dispersion analysis followed by a far-field dispersion analysis. Multi-compound aerosol thermodynamics. No liquid pool formation on the ground.
(DATAPROP ) AEROPLUME HEGADAS or PGPLUME
Same as above but instead of using SPILL's source calculation, now using AEROPLUME's own discharge model or stack calculation. Multi-compound aerosol thermodynamics.
(DATAPROP ) LPOOL HEGADAS-T
Evaporation of a liquid pool ('unpressurised release') followed by a heavy gas dispersion analysis. Multi-compound two-phase thermodynamics.
(DATAPROP ) HEGABOX HEGADAS-T
Near-field analysis for instantaneous release of initially stagnant cloud followed by far-field heavy gas dispersion analysis. Multi-compound aerosol thermodynamics or HF chemistry and thermodynamics.
HFSPILL HFPLUME HEGADAS or PGPLUME
For HF releases from a pressurised vessel with a near-field jet dispersion analysis followed by a far-field dispersion analysis. HF chemistry and thermodynamics.
HFSPILL LPOOL HEGADAS-T
HF releases from a vessel leading to an evaporating pool, followed by a heavy gas dispersion analysis. HF chemistry and thermodynamics.
It is always possible to consider only part of the mentioned scenarios.
Please note that there is no scenario going from SPILL to LPOOL. The SPILL to AEROPLUME scenario assumes that all momentum of the pressurised release is conserved. If the momentum is destroyed, that is if a liquid pool rather than a jet forms, then the discharge model within LPOOL can be used to calculate discharge rates. The discharge correlations used in LPOOL are very similar to the ones used in SPILL.
In all of the above mentioned situations it is necessary to transfer information generated by one HGSYSTEM module to the next one to be run. In HGSYSTEM this is done by using so-called link files. After running the first model, a link file is created by this model. A link file contains all information available to the first model and needed by subsequent models. Thus a link file for a model contains part of the information needed in a complete input file. The additional data needed to build a complete input file is given in a so-called partial input file.
Therefore to run a subsequent model in a series, both a link file and a partial input file must be available to make the necessary input data complete.
Example partial input files are available in directory C:\HGSYSTEM\STINPUT for all possible situations as discussed above.
4.2. Running subsequent (linked) models using the interactive program
The easiest way to run a series of subsequent HGSYSTEM models is by using the interactive utility program HGINTER. This program starts a question-and-answer session and based on the information given by the user it will determine which HGSYSTEM modules to run and in what order. The interactive program deals with link files and partial input files and their concatenation completely automatically. The user is given the opportunity to change (partial) input files based on the example files given in C:\HGSYSTEM\STINPUT. The user will also be given the choice to look at intermediate report files on the screen after a model has been run.
To start an interactive session, the user simply gives the following command from a working directory:
HGSYSTEM CASENAME
where all files generated during this interactive session will have a file name starting with CASENAME. All files will be created in the directory where the command is given. Please do not give this command while in an HGSYSTEM (sub)directory. It is strongly advised to create a separate working directory (for example C:\HGWORK) to run HGSYSTEM models from.
Using the interactive utility is strongly recommended for novice users of HGSYSTEM.
More experienced users can use manual linking of subsequent HGSYSTEM modules as will be explained in the next paragraph.
4.3. Manual linking of subsequent HGSYSTEM modules
Once a link file and a partial input file have been created, the subsequent model can be run by the following command:
MODELNAME OLDNAME.MML OLDNAME.MMP (NEWNAME)
where MODELNAME is the name of the subsequent HGSYSTEM module (see Chapter 3), OLDNAME.MML is the name of the link file and OLDNAME.MMP the name of the partial input file. NEWNAME will be the new case name for this run. NEWNAME is optional. MM is a two-character code which corresponds to the model MODELNAME that is being used.
For file name conventions see Chapter 3. In Chapter 3 the correct characters for MM, depending on the MODELNAME used, are also given.
The last character of the three-character file name extension for a link file is always an 'L'. For a partial input file it is always a 'P'.
Following this command, the MODELNAME batch file will 'concatenate' (combine, merge) the link file and the partial input file into a single input file and then execute the HGSYSTEM model MODELNAME in the usual way.
The user can merge the link file and partial input file manually by using a file editor but this is not necessary.
As an example consider running AEROPLUME using data generated by DATAPROP. Suppose a DATAPROP input file EXAMPLE.DPI has been created. First DATAPROP is run using the command:
DATAPROP EXAMPLE
DATAPROP will generate a report file EXAMPLE.DPR and several link files. One of the link files is intended for AEROPLUME and is called EXAMPLE.APL. A partial input file, supplementing the input data in EXAMPLE.APL, can be found in the HGSYSTEM sub-directory C:\HGSYSTEM\STINPUT. A partial input file for AEROPLUME has the file extension APP (see Chapter 3 on file name conventions). The sub-directory contains two file with this extension: STDP.APP and STSPILL.APP. The first partial input file supplements data generated by DATAPROP and the second one supplements data generated by SPILL. See the scenarios mentioned above to check that both DATAPROP and SPILL can provide a link to AEROPLUME.
In this example we need the STDP.APP partial input file. This file can be copied to a working directory and be edited to update parameter values as required. Assuming the name of this partial input file has been changed to NEWCASE.APP, the AEROPLUME model can be run with the link file data and the partial input data by the command:
AEROPLUME EXAMPLE.APL NEWCASE.APP NEWNAME
All files created by AEROPLUME will now have a filename beginning with NEWNAME.
AEROPLUME will create a new input file NEWNAME.API which is the combination of EXAMPLE.APL and NEWCASE.APP. The rest of the program execution is as usual (see Chapter 3).
4.4. General batch command for HGSYSTEM modules
The command given above to run an HGSYSTEM model using two data files (a link file and a partial input file) is a special case of the following general command:
MODELNAME FILE1.EXT FILE2.EX2 ... FILEn.EXn NEWNAME
where n is an integer number 1.
The n files FILE1.EX1 etc. all contain some input blocks for the model MODELNAME. The files will all be combined (concatenated) to one new input file NEWNAME.MMI before the model will be run.
It is possible to have several specifications for a certain input parameter occurring in several of the used files. If this parameter can only occur once in an input file, then the last specified value will be used in the new input file. If the parameter can occur more than once, then all specified values will be used. If in this case the total number of parameter specifications is too high, an error message will be generated by FFMAIN in the usual way.