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[lsdyna928]

Hello,

I am new to MPP LS-DYNA and have a few questions. I create my model on a single processor (a regular PC), but it will eventually be run on a cluster, so I am trying to understand the MPP-related settings and keywords.

a) While reading the documentation about output files, I came across the BINARY option for several output databases (I have attached a screenshot to illustrate my question). So far, I have always used the default value for BINARY.The documentation states:

Flag for binary output...

EQ.1: ASCII file is written. This is the default for shared memory parallel (SMP) LS-DYNA executables.
EQ.2: Data written to a binary database binout, which contains data that would otherwise be output to the ASCII file. The ASCII file in this case is not created. This is the default for MPP LS-DYNA executables.
EQ.3: ASCII file is written, and the data is also written to the binary database (NOTE: MPP LS-DYNA executables will only produce the binary database).

Since EQ.2 is listed as the default for MPP LS-DYNA, does this mean that when I run my existing model.k file on the cluster, the output will automatically be written in binary format? Or should I explicitly set BINARY= 2 because I know the simulation will be run using the MPP executable?

 

b) When LS-DYNA writes binary output files (such as binary file), can they be read directly in LS-PrePost?

 

c) Under the CONTROL keywords, I noticed *CONTROL_MPP_DECOMPOSITION_FILE_{OPTION}. From the documentation, my understanding is that this keyword can either: create a decomposition file and terminate the simulation, or read a previously generated decomposition file. If I do not use this keyword at all, what happens? Will LS-DYNA automatically perform the domain decomposition and continue running the simulation, or is there another default behavior?

 

d)would you please explain the usage of this keyword:  CONTROL_MPP_DECOMPOSITION_FLAG_STRESS_STRAIN_CURVE ?

 

e ) Do you happen to have any tutorials for learning MPP LS-DYNA?

Thank you very much for your time and help.

 

[Nanda Veralla]

Hello User,

• Need BINARY=2 explicitly? : Usually no. MPP defaults often already behave as BINARY=2, but explicitly setting it is good practice.
• Can LS-PrePost read binary files? : Yes, including binout and d3plot files. See below:
  • 
• No *CONTROL_MPP_DECOMPOSITION_FILE specified? : LS-DYNA automatically decomposes the model and runs normally.
• *_FLAG_STRESS_STRAIN_CURVE purpose? : Helps decomposition/load balancing account for material nonlinearity and stress-update cost, improving MPP efficiency in some models.

The documentation is usually good enough to get a starting point. You can refer to this additinally if you want: https://ftp.lstc.com/anonymous/outgoing/support/FAQ/mpp.getting_started

Also this: How to select, modify, and display the domain decomposition in MPP LS-DYNA? | Ansys Knowledge

Let me know if you need anything else. Keep up the simulations!🙂

Regards,

Nanda.

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