If using the simulation studies in your Design Study, evaluating the results of the initial studies helps you define the Design Study problem. In particular, it is useful to examine the quantities that you want to use as constraints.
The results of the initial studies give you a good idea of what the current values of the sensors are. Do not specify constraints or goals that are far away from the current values, therefore making an optimization impossible. Before performing an optimization, try running simulations for a range of variable values, especially dimensions, to make sure that the model rebuilds at each value.