Possible inconsistency between LS-PrePost and manual for ICFD_BOUNDARY_PRESCRIBED_SPTRANSP_CONC

[Cai Jiyu]

Hello everyone,

I encountered a possible inconsistency when setting the concentration boundary condition for species transport in LS-DYNA.

The keyword *ICFD_BOUNDARY_PRESCRIBED_SPTRANSP_CONC appears differently in the LS-PrePost keyword interface and in the LS-DYNA manual.

In LS-PrePost, the keyword is shown as a two-line structure:

• the first line defines the PID

• the second line contains the LCID values

However, in the LS-DYNA manual, the keyword is documented in a single-line format where PID, LCID and CONC fields appear together.

Because of this difference, I observed the following behaviour:

1. If I follow the format shown in LS-PrePost, the solver produces an error:

input conversion error
forrtl: severe (64)

and the simulation cannot start.

2. Even if I instead follow the manual format and remove the second line, the simulation runs but the concentration boundary condition does not seem to be applied. In this case:

• the inlet concentration remains zero

• residuals for the scalar transport equation are not computed
  

  

  
  

I also noticed a similar mismatch for another keyword related to species transport:

*ICFD_MODEL_SPECIES_TRANSPORT

where the format in the LS-PrePost interface does not fully match the manual description.

Because of this inconsistency I am currently unable to run simulations that require inlet concentration boundary conditions for species transport.

Could anyone clarify:

• The correct keyword format  *ICFD_BOUNDARY_PRESCRIBED_SPTRANSP_CONC

• whether this difference between LS-PrePost and the manual is expected

• or if this might be a bug?

My LS-DYNA version: R16 SMP and LS-PrePost version: 4.12.6

Thank you so so so much for any guidance!