Apparatus and methods for simulating a steady state condition for an unknown variable in a system are provided. One apparatus includes a processor and memory configured to store a model of the system, and first and second predictions modules. The model is configured to receive a plurality of fixed inputs representing known variables for the model, the first prediction module is configured to generate an open loop prediction for the unknown variable based on the fixed inputs, and the second prediction module is configured to generate a closed loop prediction for the unknown variable based on the open loop prediction. A method includes the steps of receiving a plurality of fixed inputs in the system model, generating an open loop prediction for the unknown variable based on the plurality of fixed inputs, and generating a closed loop prediction for the unknown variable based on the open loop prediction.