Makers of MOSES - The Final Answer in Marine Simulation
What Is New In Rev 7.04

General Changes:

  • Emitting Models has been changed so that if the TITLE and SUBTITLE are not blank then they will be included as comments in the emitted file. Also, these commands honor the -NOTE option and any note specified will also be include in the exported file. Click here, to see the documentation.

  • The way of changing the association of pressure and drift packets with body has been changed. In the past, one used special commands in the HYDRODYNAMICS menu to change the association. Thus (A_PRESSURE and A_MDRIFT) are no longer valid. Now, the association is done with options on the &DESCRIBE BODY command. Click here, to see the documentation.

  • The "WIZARDS" that are used in the MOSES tool bar have been documented. Click here, to see the documentation.

  • The -NPERIOD option for many FREQ_RESP commands has been removed from the documentation and replaced with the -E_PERIOD option. Here instead of giving an increment and a number of periods, the periods themselves are specified. Click here, here, here, here, or here to see the documentation.

  • The soil summary has been moved from DATA_SUM to CLASS_SUM and the DATA_SUM command has been replaced with S_GRID_SUM. Click here to see the documentation.

  • A new option -IG_DOFS has been added to the &CONVERT command. Click here to see the documentation. to see the documentation.

  • A new option -DO_HORIZONTAL has been added to the I_CONNECTOR V_CAN command . Click here to see the documentation.

  • The ST_CLEARANCE command has been expanded to give more information. In particular, it now reports relative velocity and a "slam" velocity. Click here to see the documentation or here to see a sample.

Convolution Computation:

One of the leading causes of numerical instability is a badly behaved convolution. In fact, with a convolution, it is possible to take too small a time step! There is a limit to how much velocity history can be stored. For extremely small time steps, this history may not be long enough to adequately describe the damping. We have changed the way the convolution is computed so the it can be integrated at a larger time step than that used to solve the equations of motion. Thus, one can evaluate the convolution with a reasonable time step (around .25 second) and still use a time step small enough to get good results for an impact problem. Click here to see the documentation.

Mean Forces:

The way mean drift forces are computed has been changed. In the past, there were two methods SALVESEN and PRESSURE INTEGRATION. The pressure integration method has always been the better way, but if one uses strip theory, they get zero surge force because the surge diffraction potential is neglected. For this reason, the default was "SALVESEN". Now, pressure integration is used unless it produces zero surge component. When this happens, the SALVESEN surge component is used. Click here, to see the documentation. As a result, the -MD_TYPE option on the G_PRESS command and the MD_CREATE command are no longer useful and are now ignored.

The setting of drift multipliers and phases is is done with options on the &DESCRIBE BODY command Click here, to see the documentation. As a result, the -MD_FORCE, -MD_MOTION, and -MD_PHASE options are now ignored on commands in the HYDRODYNAMICS Menu.

In the past, one would use the MD_MOTION command to add motion contributions to the mean force. Now this is done automatically by using the last RAOs computed for the current process. As a result, the MD_MOTION command is no longer valid.

In the past, the contribution of the coriolis acceleration to the mean force was ignored except for time domain. Now, it is included for except for time domain where it is computed exactly.

Frequency Domain Beam Slam Fatigue:

In the past, there was no good way to assess the fatigue damage due to slamming. While this is properly accounted for in the time domain, most fatigue studies are carried out in the frequency domain. We now have a conservative way of including the fatigue damage for beams which are out of the water in the mean condition. Click here to see the documentation.

Tubular Joints and SCFs:

In the past, the concept of Tubular Joints was used for Structural Post-Processing and little else, and the data associated with them was generated when it was needed. This has now changed. Instead of defining special joint properties on a "JNT_PROP" command, the are now defined on either the command which defines the point (which is a tubular joint), or on a ED_POINT command, Click here to see the documentation. On implication of this is that the SCF data is defined when the point is defined, so some flexibility is lost. The gain, however, is that the joint SCFs can not be used in computing beam fatigue. As a result, several options of both &REP_SEL and JOINT_POST have been removed and are now ignored.

Pictures:

  • One can now build a file containing a picture which can be processed by a ray tracing program. Click here to see the documentation.

  • A new option, -STRESS, has been added to &PICTURE which allows selecting based on stress ratio. Click here to see the documentation.

  • A new option, -WG_MIN, has been added to &PICTURE which allows one to set the minimum wave grid size. Click here to see the documentation.

The Environment:

  • One can now input a wind spectrum. Click here, to see the documentation, or here to see a sample.

  • In a continuing effort to make things more consistent, several options on the &ENV command and commands in the &DATA ENV menu have had their names changed. In particular:
       -TEMPRESS -T_PRESSURE
       -P_WIND -W_PERIOD
       -P_WAVE -S_PERIOD
       -P_DRIFT -MD_PERIOD
       -MGROWTH -M_GROWTH
       TEMPRESS T_PRESSURE
       MGROWTH M_GROWTH
       GRID S_GRID
       PROFILE C_PROFILE
       WIND_HISTORY W_HISTORY
    Click here, to see the documentation. The old options and commands still work, but are no longer documented.

PRCPOST:

  • A new command, BODY_FORCE, has been added to the PRCPOST Menu. This command reports the force, by type, applied to each body during a process. Click here to see the documentation.

  • The formatting of several reports has changed so that the way of reporting numbers is more consistent.

  • Allowing the user to control the definition of "MAGNITUDE" has been extended to the TRAJECTORY, ELMFORCE, LDGFORCE, and BODY_FORCE Click here or here to see the documentation.

&STATUS:

  • For some types of &STATUS, one can now use a new option, -PLOT, which will put the user in the Disposition Menu so he can plot the results. Click here to see the documentation. A new restriction applies here in that any status which allows for a -PLOT option will on allow for a single item (connector) to be selected for display.

  • The G_ROD type of STATUS has been removed from the documentation because it is exactly the same as DG_CONNECTOR.

  • Three new values for &STATUS have been added: SEA_SPECTRUM, SEA_TSERIES, and WIND_TSERIES. The first of these gives information on the sea spectrum and the last two give the frequencies, periods, amplitudes, and phases of the Fourier series that represent the wind and sea in the time domain. Click here to see the documentation.

String Functions:

  • A new action, MENU, has been added to the &INFO string function. Click here to see the documentation.

  • A new action, CURRENT, has been added to the &PIECE string function. Click here to see the documentation.

  • Two new options for &ELEMENT string function have been added. ELE_TYPE returns the type of element: BEAM, PLATE, or OTHER, and SUBELEMENTS returns the names of the subelements which belong to the specified element. Also, a new string function, &SUBELEMENT, has been added which returns information about plate subelements. Click here to see the documentation or here to see an example.

What No Longer Works:

  • One can only select a single connector for display with &STATUS DG_CONNECTOR, &STATUS S_ROD, and &STATUS H_ROD.

  • If you have a data set or macro which depends on knowing the columns of data resulting from the TRAJECTORY, then the change of adding the magnitude of the velocity and acceleration will break that code.

  • The HYDRODYNAMIC commands: A_PRESSURE, A_MDRIFT, MD_MOTION, and G_MDRIFT are now ignored.

  • The options: -MD_FORCE, -MD_MOTION, and -MD_PHASE are now ignored on commands in the HYDRODYNAMICS Menu.

  • The options -SCF, -MIN_SCF, and -BBC_MUL on the &REP_SEL and JOINT_POST commands are now ignored.

  • The options -IN_SCF on the &REP_SEL and BEAM_POST commands are also ignored and it is now an option on &PARAMETER.

  • The command DATA_SUM has been replaced with S_GRID_SUM to get a summary for wave grids, and CLASS_SUM SOIL for a summary of soils.

What Answers Will Change:

  • Any time domain which uses a convolution and which has a time step smaller that that defined with the &DEFAULT -DT_CONVOLUTION option will change. Also, if one gets a message that options are now "ignored" it will probably change the answers.

  • The changes made in the computation of the mean forces will definitely change the results of both static and time domain simulations.