MOOSE Newsletter (June 2021)

Multiple input file support

Users can now supply multiple input file names after the -i option. The supplied inputs are successively merged into one simulation specification, with later files adding and overwriting parameters. This allows users to factor out common parameters (e.g. solver options, postprocessors, outputs) from a set of similar input files

 ./mooseapp-opt -i common_parameters.i simulation_1.i

The output file names will be based off the last input file name specified (unless the Outputs/file_base parameter is specified). When multiple inputs are specified, MOOSE will inform the user about parameter overrides at the top of the simulation output.

To assist users with refactoring input files several new functions we added to the hit commandline tool.

hit merge -output outfile.i infile1.i infile2.i ... will produce a single file outfile.i that is a merge of the infile*.i inputs (which would result in the same MOOSE simulation as the multiple input files).
hit diff left.i right.i or hit diff -left left1.i left2.i ... -right right1.i right2.i ... performs a diff on the left and right files (in the second example merging all left and right files respectively first). This diff is not sensitive to order, formatting, or comments in the input files.
hit common file1.i file2.i ... > common_parameters.i will extract all parameters that are common to the specified input files (and have the same values). This can be used as the first step in factoring out common settings into a single input file.
hit subtract common_parameters.i simulation_1_full.i > simulation_1.i removes the parameters in common_parameters.i from simulation_1_full.i, creating simulation_1.i. This is the second step in factoring out common parameters from a set of input files. The resulting file can be run as ./mooseapp-opt -i common.i simulation_1.i and will result in the same simulation as ./mooseapp-opt -i simulation_1_full.i.

Improvements to the finite volume capabilities

Several new interface kernels were added for the finite volume (fluid flow in particular) simulations: a general diffusion interface kernel FVDiffusionInterface and a variable continuity constraint kernel, FVTwoVarContinuityConstraint
The related postprocessors were implemented to measure the heat flux across these interfaces, namely InterfaceDiffusiveFluxAverage/Integral

libMesh-level changes

Improved BoundingBox performance
active_local_subdomain_set mesh iterators
MeshFunction::set_subdomain_ids() option
GenericProjector made more flexible, for solution transfer use
SIDE_HIERARCHIC finite element type added, for variables defined on interfaces between elements.
Minor bug fixes, compatibility fixes

Bug Fixes and Minor Enhancements

A ParsedPostprocessor was added to the framework. This removes the need for numerous more specific postprocessors, such as the DifferencePostprocessor or the ScalePostprocessor, which will be kept for backwards compatibility of inputs.
TIME_SECTION macros within tight and possible threaded regions within the stochastic tools module were removed, see #18172.

Other news

The codeowners feature was activated for the MOOSE repository. When pull requests modify specific sections of the code, the respective code owner will automatically be contacted for a review.