Systems and methods for controlling a fluid based engineering system are disclosed. The systems and methods may include a model processor for generating a model output, the model processor including a set state module for setting dynamic states of the model processor, the dynamic states input to an open loop model based on the model operating mode, where the open loop model generates current state derivatives, solver state errors, and synthesized parameters as a function of the dynamic states and a model input vector, where a constraint on the current state derivatives and solver state errors is based a series of cycle synthesis modules. The series of cycle synthesis modules may include a flow module for mapping a flow curve relating a compressible flow function to a pressure ratio and for defining a solution point located on the flow curve and a base point located off the flow curve.