The ramping controlled by System Coupling is used to improve convergence of the overall analysis. It works by slowing the application of the source-side value on the target-side of the data transfer. For each data transfer location (node) where is true, the following formula is applied:

(4)

where

When ramping is enabled (that is, for System Coupling in Workbench, the Ramping setting is set to Linear to Minimum Iterations; or for System Coupling's GUI or CLI, the RampingOption setting is set to Linear), within each coupling step, the ramping factor is used to linearly increase the change in the data transfer value applied to the target side of the interface. The data transfer value is increased during each coupling iteration until the specified minimum number of coupling iterations, , is reached.

The ramping factor is applied to the change in the data transfer value from the last coupling iteration of the previous coupling step. If there is no change in this value from the last coupling step, the full data transfer value is applied to the target side of the interface for all coupling iterations of that coupling step.

During the coupling iteration (for ), the ramping factor equals . The full data transfer value is applied for all coupling iterations that are equal to or greater than the minimum number of coupling iterations. As is always reached, the full data transfer value is always applied by the end of each coupling step. This ramping behavior is demonstrated in Figure 45: Schematic of the Linear to Minimum Iterations ramping concept for the case where the minimum number of iterations specified is 5.

When ramping using the Linear to Minimum Iterations or Linear option, if the minimum number of iterations is the same as the maximum number of iterations, then it is unlikely that the data transfer will converge. It is a best practice to set the maximum iterations to be larger than the minimum iterations.

Figure 45: Schematic of the Linear to Minimum Iterations ramping concept