A Computational Modelling Developer designs and implements mathematical models for the simulation of complex systems using computers. They use various programming languages and software to create models that simulate real-world scenarios in fields such as physics, biology, finance, or engineering. They analyze data, formulate algorithms, and develop computational solutions to predict the behavior and outcome of these systems. They also test and refine these models to ensure accuracy, and often collaborate with other professionals to apply these models to solve practical problems or to aid in decision-making processes.