- MOOSE is capable of running multiple applications together and transfer data between the various applications.

- This problem replaces the thermal conductivity calculated by the Material with a value computed by another application that runs a phase-based micro-structure simulation.

[MultiApps](/wiki/MooseSystems/MultiApps)

[Transfers](/wiki/MooseSystems/Transfers)

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# Create Micro-structure Calculation

1. Represent the packed steel balls as a continuous phase variable between 0 and 1.
    - 0 = water
    - 1 = steel
1. Modify `PackedColumn` to compute porosity from phase variable.
1. Create an `AuxKernel` that corrodes the steel as a function of temperature.
1. Compute the "effective" thermal conductivity across the domain.

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[step10_multiapps/include/materials/PackedColumn.h](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/include/materials/PackedColumn.h)

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[step10_multiapps/src/materials/PackedColumn.C](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/src/materials/PackedColumn.C)

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[step10_multiapps/include/auxkernels/RandomCorrosion.h](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/include/auxkernels/RandomCorrosion.h)

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[step10_multiapps/src/auxkernels/RandomCorrosion.C](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/src/auxkernels/RandomCorrosion.C)

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[step10_multiapps/problems/step10_micro.i](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/problems/step10_micro.i)

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## Add a Micro-structure Test

[step10_multiapps/tests/auxkernels/corrosion/corrosion.i](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/tests/auxkernels/corrosion/corrosion.i)

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# Engineering Scale Calculation

1. Modify `PackedColumn` to use a variable for thermal conductivity rather than computing it.
2. Setup the engineering scale problem to run micro-structure calculations to compute conductivity at a series of points and interpolate the data into a continuous field.

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[step10_multiapps/include/materials/PackedColumn.h](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/include/materials/PackedColumn.h)

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[step10_multiapps/src/materials/PackedColumn.C](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/src/materials/PackedColumn.C)

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[step10_multiapps/problems/step10.i](https://github.com/idaholab/moose/blob/devel/tutorials/darcy_thermo_mech/step10_multiapps/problems/step10.i)