The large problem executables store integer numbers as 64-bit words. These executables allow larger mesh sizes than the default executables. A large problem executable requires twice the integer memory of a default executable, for a given problem and grid size. There is no advantage to using a large problem executable unless the problem size requires it. This feature is not available to use in any case with System Coupling . You might receive the following errors: +——————————————————————–+ | ERROR #001100279 has occurred in subroutine ErrAction. | | Message: | | FATAL ERROR: You are not allowed to use a large-problem-size flow | | solver in a system coupling simulation. | | ERROR #001100279 has occurred in subroutine ErrAction. | | Message: | | 1 fatal error found in the problem setup. | ERROR #001100279 has occurred in subroutine ErrAction. | | Message: | | Stopped in routine CHECK_INIT |