Constructor and Destructor

An object is generted by the cast of class. If it completes its job and have to disappear, a method of "destroy" is effective for post-treatment of the instance. The "destroy" method sulvage the memory resource from  the dead object. Here, however, the ressuerection of a dead object on code is applied instead of  this combination of constructor and destructor.

The boolean data "true" is given to a object's life  at the in-flow boundary. and it is floating along the flow by a specified time step. At each time step, the life condition is checked and if the particle is out of boundary, the boolean data "false" arrived to the object.