Mean-flow file#

FELiCS imports mean-flow information using HDF5-based files.

Two types of mean-flow files are currently supported:

.fel files containing mean-flow data defined on external CFD grids,
MeanFlow.h5 files previously exported by FELiCS on the computational mesh.

The mean-flow file used by a simulation is specified through FlowInput.MeanFlowFilePath.

Workflows to import mean flows#

FELiCS supports two approaches for importing mean-flow fields, depending on the value of the Case.needInterpolation parameter.

1. With interpolation#

When needInterpolation: true, FELiCS assumes that the mean flow is defined on a grid different from the computational mesh.

The imported fields are then linearly interpolated onto the FEM mesh defined by MeshFilePath.

This is typically used with .fel files generated from:

CFD simulations,
experimental reconstructions,
analytical models.

Example configuration:

{
    "Case": {
        "needInterpolation": true,
        "MeshFilePath": "mesh.msh"
    },

    "FlowInput": {
        "MeanFlowFilePath": "meanflow.fel"
    }
}

For large meshes, particularly 3D cases, the interpolation step can become time-consuming.

After interpolation, FELiCS automatically exports the interpolated fields to the output directory defined in Export.ExportFolder as MeanFlow.h5.

2. Without interpolation#

When needInterpolation: false, FELiCS assumes that the imported mean flow was previously exported by FELiCS (typically as MeanFlow.h5) on the same computational mesh as the current run.

Instead of interpolating the fields, FELiCS directly maps the imported degrees of freedom onto that of the current FEM spaces.

This avoids the interpolation step and can significantly reduce preprocessing time for large 3D simulations.

Example configuration:

{
    "Case": {
        "needInterpolation": false,
        "MeshFilePath": "mesh.msh"
    },

    "FlowInput": {
        "MeanFlowFilePath": "MeanFlow.h5"
    }
}

`.fel` file structure#

A .fel file stores mean-flow information using the HDF5 format.

The file should contain:

the coordinates of the points where the mean flow is defined,
and the corresponding mean-flow variables.

Vector variables are stored component-wise by appending the coordinate name to the vector name.

Example structure for a 2D Cartesian flow containing coordinates (x,y), velocity vector u, and density rho:

/MeanFlow/x
/MeanFlow/y
/MeanFlow/ux
/MeanFlow/uy
/MeanFlow/rho

💡Note: the name of coordinates (and vector components) must be coherent with the coordinate system defined in Case.CoordinateSystem. E.g. (x, y, z) for 3D cartesian coordinates or (x, r, t) for 3D cylindrical coordinates.

`.h5` file structure#

The structure of this files is described in the FELiCS output files.

Mean-flow file

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