/DT/NODA/Keyword3/Iflag
Engine Keyword Activates the nodal time step control method with the option to apply mass scaling to increase a model’s time step.
Format
 /DT/NODA/Keyword3/Iflag
 $\text{\Delta}{T}_{sca}$ $\text{\Delta}{T}_{\mathrm{min}}$
 If Iflag=1, insert the next line
 grnd_ID
Definitions
Data  Description  SI Unit Example 

Keyword3  Time step control
type. 1
If Keyword3 is not specified, as in /DT/NODA/Iflag, then the computation will use the nodal time step and $\text{\Delta}{T}_{\mathrm{min}}$ is not used. 

Iflag  Node group flag.


$\text{\Delta}{T}_{sca}$  Scale factor on
critical nodal time step. Default = 0.9 

$\text{\Delta}{T}_{\mathrm{min}}$  Minimum time step  
grnd_ID  The nodal time step method is only applied to the nodes in this node group, read only if Iflag=1. 
Comments
 For all
Keyword3 options, the time step control will be activated
when the time step of the node controlling the time step of the simulation
becomes less than:
$\frac{\text{\Delta}{T}_{\mathrm{min}}}{\text{\Delta}{T}_{sca}}$
 Only one /DT/NODA/Keyword3 option can be used in a simulation.
 When using Nodal time step, the computation of each cycle is slightly more expensive but the time step can be higher especially for low quality meshes.
 When /DT/NODA/Iflag is used, the computation will use the nodal time step method and $\text{\Delta}{T}_{\mathrm{min}}$ is not used.
 To determine how much mass will be added to a model, Radioss calculates a target time step for different amounts of percent mass increase and prints this information as a table and a graph in the Starter output file.
 /DT/NODA/Keyword3 is compatible with all options of /DT/Eltyp/Keyword3.
 /DT/NODA and /DT/NODA/CST* are compatible with /DT/INTER/AMS from version 2017.2.3.
 /DT/NODA/CTS* is
compatible with advanced mass scaling, /DT/AMS. If used with
/DT/AMS, AMS will be applied to the part group defined in
Starter /AMS card and /DT/NODA/CST* applied to
nodes not belonging to the AMS part group.For example:
 /DT/AMS/1
 $\text{\Delta}{T}_{sca1}$ $\text{\Delta}{T}_{\mathrm{min}1}$
 Tol_AMS
 /DT/NODA/CST, /DT/NODA/CST1, /DT/NODA/CST2
 $\text{\Delta}{T}_{sca1}$ $\text{\Delta}{T}_{\mathrm{min}1}$
This is even advised in order to minimize computing time in models where AMS only applies to selected parts.Note: It is pointless to use a higher time step in AMS than the one used in classic mass scaling since the smaller time step limits the performance.