3. Definition of the list of moments - keyword DEFI_LIST#

3.1. Operands LIST_INST and VALE#

The calculation times can be defined in 3 different ways:

  • or by entering the keyword LIST_INST with a concept defined in advance by the operator DEFI_LIST_REEL u4.34.01,

  • or by entering the keyword VALE with a list of real ones,

or by entering the keyword RESULTAT with a concept produced by STAT_NON_LINE or DYNA_NON_LINE. This keyword allows you to refine an already existing list of moments. In fact, we then define a list of moments SUBD_PAS* times finer** than the list of moments actually calculated in STAT_NON_LINE or DYNA_NON_LINE. It should be noted that this list of moments actually calculated may be different from the list of moments given as the input of STAT_NON_LINE or DYNA_NON_LINE (for example because of sub-division) and from the list of archived moments (if you do not archive all the moments). This feature is useful for verifying the independence of the results from time discretization. For example, to obtain a list of moments twice as fine, we choose SUBD_PAS =2.

lookout

If the result SD comes from a repeat calculation, it is not possible to reuse it in the command because you cannot extract a list of unique moments (some moments will be duplicated).

3.2. Operands PAS_MINI, PAS_MAXI, NB_PAS_MAXI#

These operands need only be entered in case of automatic management of the list of moments (METHODE =” AUTO “).

_images/Cadre2.gif

Fig. 3.1 Automatic adaptation of the time step#

The PAS_MINI operand allows you to specify the minimum time step. If, during the adaptation of the time step, we have to process a time step less than PAS_MINI, then the calculation stops. If this operand is not entered, in the general case PAS_MINI is then equal to \({10}^{-12}\) (this is also the minimum authorized value); if it is not entered and MODE_CALCUL_TPLUS =” IMPLEX “, then the PAS_MINI is equal to 1/1000th of the first calculation step (necessarily entered by the user via LIST_INST).

If \(\Delta {t}_{2}<\text{PAS_MINI}\) \(\to STOP\)

Attention, the verification of PAS_MINI is not carried out during the possible sub-division of the time step in case of failure (it is SUBD_PAS_MINI which acts during the sub-division). The PAS_MINI operand only acts to calculate a new time step.

The PAS_MAXI operand allows you to specify the maximum time step, but it works differently than PAS_MINI. In fact, if during the adaptation of the time step, we are required to process a time step greater than PAS_MAXI, then the calculation does not stop (contrary to the operation of PAS_MINI), but the time step is then limited to PAS_MAXI. If this operand is not filled in, we will not do this step; if it is not filled in and MODE_CALCUL_TPLUS =” IMPLEX “, then the PAS_MAXI is worth 10 times the first calculation step (necessarily entered by the user via LIST_INST).

If \(\Delta {t}_{2}>\text{PAS_MAXI}\) \(\to \Delta {t}_{2}=\text{PAS_MAXI}\)

The NB_PAS_MAXI operand allows you to specify the number of time steps after which the calculation stops. The default value is one million (it is also the maximum allowed value).