The Sim. Parameters Tab controls how a simulation will be run. Setting these parameters properly is important, because once an optimization run has started, there is no further operator intervention. If a simulation is run improperly, it will affect ALL simulations in the run.
You can choose between single cycle and multiple cycle simulations, when to stop a simulation, and whether to run radiation view factor calculations on each mesh. One technique you can use to speed up an optimization run is to Stop When: 100% Solid Casting is selected. In this way you will not be running calculations just to find out how long it takes the risers to freeze. When the casting is solid, the evaluation will be done, and the next simulation set up and run, if needed.