Execution

Command Line

The main mode of interaction with MOOSE-based applications is the command line. The executable is run with an input file, which may produce output file(s):

-i input_file.i

Based on your installation of the application, the exact command how to run the code can differ; see the follwing subsections below.

commentnote

Note: Further details on command line switches are in the user manual.

Pre-installed Version

If you are using pre-installed version of the code (like on INL HPC, for example), the executable should be in your path and the above command should work.

Self-built Version

If you built the code yourself, you can run it via:

/path/to/ -i input_file.i

If you are running from the location where you built the executable, you will need to prepend ./, so the command would be:

./ -i input_file.i

In later steps of this tutorial, we will look at how to build such an input file and how to view the obtained results.

Terminal Output

In this section we explain different sections that are diplayed during the execution:

Framework information gives an overview of used dependent libraries. This is useful information to provide if you ever need to report a problem or ask for help.

Framework Information:
MOOSE Version:           git commit b5a350860f on 2021-09-28
LibMesh Version:         aebb5a5c0e1f6d8cf523a720e19f70a6d17c0236
PETSc Version:           3.14.2
Current Time:            Thu Sep 30 14:25:58 2021
Executable Timestamp:    Tue Sep 28 14:05:09 2021

The parallelism section will tell you how many MPI processes and/or threads your run is using.

Parallelism:
  Num Processors:          1
  Num Threads:             1

The mesh section provides information about how many elements and nodes are used in the simulation.

Mesh:
  Parallel Type:           replicated
  Mesh Dimension:          1
  Spatial Dimension:       3
  Nodes:                   51
  Elems:                   50
  Num Subdomains:          1

The system information tells you how many degrees of freedom (DOFs) you have in the whole simulation and per MPI process (local DOFs). It also lists the primary and auxiliary varaibles present in your simulation.

Nonlinear System:
  Num DOFs:                350
  Num Local DOFs:          350
  Variables:               { "rhoA" "rhoEA" "rhouA" }
  Finite Element Types:    "MONOMIAL"
  Approximation Orders:    "CONSTANT"

Auxiliary System:
  Num DOFs:                1001
  Num Local DOFs:          1001
  Variables:               "A" "A_linear" { "H" "P_hf" "T" "e" "p" "rho" "v" "vel" }
  Finite Element Types:    "MONOMIAL" "LAGRANGE" "MONOMIAL"
  Approximation Orders:    "CONSTANT" "FIRST" "CONSTANT"

The execution information provides information about the time stepper used, preconditioner, etc.

Execution Information:
  Executioner:             Transient
  TimeStepper:             ConstantDT
  Solver Mode:             Preconditioned JFNK
  MOOSE Preconditioner:    SMP

After the run header is printed, information about each time step is printed as it executes. A typical time step will tell you the simulation time, time step number and time step size (dt). The convergence history for each time step is printed out by default. You will see residuals for non-linear and linear steps and the result of the solve.

Time Step 1, time = 1e-05, dt = 1e-05
 0 Nonlinear |R| = 9.848097e+01
      0 Linear |R| = 9.848097e+01
      1 Linear |R| = 9.450620e-04
 1 Nonlinear |R| = 5.292274e-02
      0 Linear |R| = 5.292274e-02
      1 Linear |R| = 2.882857e-05
 2 Nonlinear |R| = 2.878039e-05
      0 Linear |R| = 2.878039e-05
      1 Linear |R| = 4.478868e-09
 3 Nonlinear |R| = 4.538872e-09
 Solve Converged!

If your input file contains errors, it will be reported in the terminal.

This example shows how THM-based applications report errors.

Execution stopped, the following problems were found:

2 errors:
  - Component 'pipe' does not have connected inlet.
  - Component 'pipe' does not have connected outlet.

If the error is detect by the MOOSE framework you will see something like this:

*** ERROR ***
/path/to/check_error.i:50: missing required parameter 'MultiApps/multi/input_files'
	Doc String: "The input file for each App.  If this parameter only contains one input file it will be used for all of the Apps.  When using 'positions_from_file' it is also admissable to provide one input_file per file."

Parallel Execution

The following parallel execution models are supported:

  1. Threads

  2. MPI

  3. MPI+Threads

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