sequence of X-files can be, <root>.X0000, <root>.X0010, <root>.X0015, <root>.X0023,...

<root>.X0000 is always the initial restart file (if requested). <root>.X0010 is the first restart file in the sequence (not counting the initial), and is created at milestone 10. The files <root>.S0010 and <root>.X0010 are written at the same date. (Note that this was different in early versions of Eclipse.)

12. Restarting a simulation

As described above, a restart is what we do when we pick up the simulated state at some date (where we have a restart file available), and start a new simulation from that date. Development of the state up to the point where we do the restart is then assumed to be described by the run we restart from.

In Eclipse, restarts can be done as “standard” or from SAVE files. The “standard” way is more flexible, but the SAVE way is normally faster. We will not discuss the SAVE way here.

In a “standard” restart, the simulation is defined in the usual manner, but initialised by the restart data. I.e., the restart run needs all the standard initialisation data except the equilibration which is no longer valid. The restarted run must be given a case name different from the original run. Then the procedure to create a restart run is,

Assume the original run is called CASE1.DATA. We will restart this run from time step (milestone) 20, where the state has been saved in a file CASE1.X0020.

We will name the restarted run CASE1_R1.DATA. First create CASE1_R1.DATA as a copy of

CASE1.DATA. Then edit the contents of CASE1_R1.DATA:

•In section SOLUTION delete equilibration keywords (and enumeration and analytic aquifers if used).

•Insert a keyword RESTART (in SOLUTION section) to specify which run to restart from, and at

which time step. In our example,

RESTART

‘CASE1’ 20 /

•In the SCHEDULE section delete all well and time-stepping keywords up to and including the restart time. (But see below, the SKIPREST keyword)

•Start run (from Eclipse panel you would choose CASE1_R1 as the case name)

The Eclipse post-processing software knows all about restarts, so if the last restart is given as file name, it will automatically nest itself backwards to the correct beginning.

The SKIPREST keyword

The modifications to be done in the SCHEDULE section are error-prone, and many users have had bad experiences with omitting too much or too little data. Eclipse has therefore provided a solution which is highly recommended:

If a keyword SKIPREST is inserted at the beginning of the SCHEDULE section, Eclipse will skip all data that is not needed for the defined restart, and enter the section at precisely the correct position.

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