Successful production system design and operations requires a detailed understanding of multiphase flow behavior. Flow modeling and simulation provides valuable insights into flow behavior, including the physics describing flow through the entire production systems, from reservoir pore to process facility. The OLGA dynamic multiphase flow simulator models time-dependent behaviors, or transient flow, to maximize production potential. Transient modeling is an essential component for feasibility studies and field development design. Dynamic simulation is essential in deepwater and is used extensively in both offshore and onshore developments to investigate transient behavior in pipelines and wellbores. Transient simulation with the OLGA simulator provides an added dimension to steady-state analyses by predicting system dynamics such as time-varying changes in flow rates, fluid compositions, temperature, solids deposition and operational changes. From wellbore dynamics for any well completion to pipeline systems with all types of process equipment, the OLGA simulator provides an accurate prediction of key operational conditions involving transient flow.