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Compensation of negative damping from retardation functions (Sima/Simo)

The following is confirmed from the developers of Sima / Simo:

  • Do Simo and Sima compute the damping resulting from the (truncated) retardation functions? YES
  • Do Simo and Sima add damping to compensate for a possible negative damping calculated from the retardation functions? YES
  • From which versions of Simo and Sima was this introduced? All official SIMA versions
  • Where in Sima will this damping be shown? This will be added to the linear damping matrix in the body. This means the damping contribution from this calculation is superimposed on the already existing damping matrix if it is present. The best solution though would be to create a separate linear damping matrix in the Radiation data, and add this explicitly later when running SIMO, to make this effect more clear.  

For Simo versions earlier than 4.0 (3.6, 3.4 etc., i.e. pre Sima), this damping was not computed.

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DYNMOD: What's the meaning of sum coupling force, resultant coupling force, total force?

SIMO Dynmod:

Sum coupling force: This is the sum of all coupling forces at a body

Resultat coupling force: This is the resultat (total) force for one coupling element = sqrt (fx^2 + fy^2 + fz^2)

Total force: Total force acting at a body

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How to record keyboard operations into macro files

The macro command for creating or opening a new file for recording macros is one of the following:

@OPEN <FILE> or
@CREATE <FILE>

the extension *.MAC is implicit, so if you write @OPEN NEWFILE, a file called NEWFILE.MAC will be created and the macro commands and input values for your new operations will be stored in NEWFILE.MAC.

If you want to stop recording to a file, simply write

@CLOSE <FILE>

PS: A good macro command to remember while running SIMO or MIMOSA is @HELP. This macro command shows all available macro commands and their meaning.

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How to resolve fileparse():need a valid pathname error in RSIMO

When trying to run the following command for Simo 4.2-00:

call "C:\Program Files (x86)\DNVS\Simo V4.2-00\simo\bin\rsimo" dummy dummy stamod batch sta1

The following error message shows up,and rsimo stops: fileparse(): need a valid pathname at C:\Program Files (x86)\DNVS\Simo V4.2-00\simo\bin\rsimo.exe line 3.

The workaround is as follows:

In order for rsimo.exe version 4.2 to run, you have to set the environment variable SIMO_BINDIR to the directory where the file rsimo.exe is located.

The default location for this is “C:\Program Files (x86)\DNVS\Simo V4.2-00\simo\bin”.

This setting is done automatically inside rsimo for previous versions of Simo, but unfortunately left out for the version 4.2-00.

You can include the following command as the first line of the batch file:

SET SIMO_BINDIR=C:\Program Files (x86)\DNVS\Simo V4.2-00\simo\bin

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How to run Simo in batch

Attached is an example to run Simo in batch mode.

To run Simo in batch mode, rsimo.exe is used instead of simo. exe.

Please see the attached document Batch_Example.

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INPMOD cannot read QTF force coefficients from a SIF file (DeepC/Simo)

INPMOD cannot read QTF force coefficients from a SIF file.

The coefficients must be read from WAMIT files.

The attached document shows how WADAM can "be told" not to the delete the WAMIT files.

Please see the attached document 5_Save_Wamit.

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Mass matrix definition and coordinate systems used

The mass matrix should be given in the local body coordinate system with respect to body origin (not Centre of Gravity (CoG)).

It is the user who decides where the local coordinate system of a body is located and the important input is location of CoG in this local coordinate system. 

For each single body, a specific local system exists and all the bodies use the same global system.

Furthermore, the total mass matrix is printed at prs-xxxx.lis, so one could check if a total mass matrix is correctly input.

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Max angle rate in Allocated thrusters

Related to Sima ver. 3.3-01 and Simo 4.8-02:

The "Limit thrusters" and "Max thrust" parameters are never used during the simulation and will not affect the behaviour of the numerical model. We will remove these parameters in the next major release of SIMA/SIMO.

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Output units for angles and rotations in Simo OUTMOD and S2XMOD

All results for angles and rotations are presented as DEGREES to the user when using OUTMOD and S2XMOD in Simo. (The rawdata results are stored as radians on the *.ffi files, but converted to degrees before being presented in OUTMOD and S2XMOD).

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Riflex and Simo memory settings

For the case of the memory problems, you must set the environment variable RIFLEX_DYNMOD_MEM to a higher value.

The default is 16, meaning that you have 4 million words available (=16 MB on a 32-bits system). The maximum you can set is 800 (800MB = 200 million words).

You must set the environment variable as a system variable (not a user variable). Please see the attached document for details.

If the above setting still gives you error messages about the memory, please read further down:

In some cases it is SIMO that runs out of memory (even if the error message comes from Riflex). Then you must set the environment variable SIMO_MEM. Its size is defined the same way as RIFLEX_DYNMOD_MEM. Be aware that SIMO_MEM allocates space inside RIFLEX_DYNMOD_MEM, so it cannot be set too large compared to RIFLEX_DYNMOD_MEM.

A typical "max" setting for a system of 2 GB RAM or more will be:

RIFLEX_DYNMOD_MEM = 800 SIMO_MEM = 100

Please see the attached document How to set environment variables for Riflex and Simo.

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Unable to locate license file (Simo/Riflex)

When trying to run SIMO or RIFLEX, the license file is not found automatically and a pop up box keeps appearing, prompting the user to enter the location of the license file or license server.

There are several reasons for this error:

  • The user does not have a valid license for SIMO or RIFLEX
  • The environment variable does not point to the correct location. Check the MARINTEK_LICENSE_FILE environment variable.
  • The registry key does not point to the correct location.
  • Check HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\FLEXlm License Manager
  • Check HKEY_CURRENT_USER\Software\FLEXlm License Manager

The value should be C:\Flexlm;2002@localhost 

Note that** C:\Flexlm** is not a valid value as it specifies a file, not the folder. The last \ should be removed.

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