III. The moving mesh

    The creation of a moving can't be done in a 'interactive-intuitive' way, it requires the use of the PROSTAR's commands which have to be typed on the keyboard. This is due to the high number of commands involved in the definition of the movements.

    The various moving-mesh operations are defined in terms of 'events'. Each event has a time and different elementary mesh operations associated with it. These elementary operations can be cell additions, removals, re-attachments or changes of material type... The event is executed when the solution time matches the event time.
     Events are stored in a direct access binary file which name ends by '.evn'.
    The events can be defined in any order since they are associated with a time. Here the events are defined "by zone", meaning that all the events related to a given zone - like intake valve, piston or exhaust valve - are defined separately each one at a time.

    A special event called the 'EGRID' event sets up a series of PROSTAR grid-changing that are executed at each time step. The EGRID event commands are read from a separate file (called here cgrid.cgrd) created outside the PROSTAR environment.

    The moving mesh obtained is following :

    On this animation, it is possible to see the removal and addition of the cells at the bottom to represent the piston movement and at the top to represent the valves movements.