Simulation Parameters

The ultraFluidX FW-H tool uses an .xml file to specify all required parameters.

The root element indicates the version number of the FW-H tool:

<fwh version=”2024.1.0”>

This entry is parent to all other elements in the file, so the file must always end with </fwh> according to XML standards.

The organization of parameters into categories is detailed below.

<input_files>

This category indicates which ultraFluidX input files are used as input to the FW-H calculation:

<name>: Specifies the path to one or several H3D and/or EnSight files containing partial surface or monitoring surface output generated by ultraFluidX. For unmerged data, an .sos file or a list of RANK*.case files need to be provided. For merged data, the .case file is specified.

The <general> section allows you to specify the FW-H formulation:

<formulation> [porous, solid] default: porous: You can indicate whether the porous or solid formulation of the FW-H analogy is to be used (if no setting is provided, porous will be used as default).
Note: The input data needs to correspond to this setting, that is, the porous formulation uses pressure and velocity data sampled in the volume field on a monitoring surface, while the solid formulation is based on pressure data sampled on a partial surface.

This section contains the material properties of the fluid. These quantities need to correspond to the values that were used in the original ultraFluidX calculation. If not specified, the values for <temperature>, <specific_gas_constant>, and <specific_heat_ratio> will use the default values of ultraFluidX as indicated below. The values do therefore only need to be specified if the ultraFluidX run did use different settings, for example, another fluid temperature.

<temperature>: (optional, default value = 293.15); Fluid temperature in [K]
<specific_gas_constant>: (optional, default value = 287.058); Specific gas constant of the fluid in [J/kgK]
<specific_heat_ratio>: (optional, default value = 1.4); Specific heat ratio of the fluid
<reference_acoustic_pressure>: (for example 2e-5); Reference pressure value in [Pa] used for OASPL calculation

<reflection_plane>

The FW-H tool can account for absorbing reflection planes in the domain. One plane in each direction (global x-, y-, z-) can be defined and requires the following parameters:

<x_direction>

<active>: bool : true or false; Indicates whether this plane is considered or not.
<position>: floating-point value; Indicates the position on the respective axis, that is, x-axis in this case. All coordinates are in [m].
<absorption>: floating-point value between 0 and 1.; Indicates an absorption value for the plane:; Fully rigid plane: absorption = 0; Grass: absorption ~ 0.6; Fully absorbing material: absorption = 1

The same parameters can be used for planes in categories

<y_direction>

<z_direction>

<probe_output>

<name>: Indicates the name of the pressure signal output files.; In the output folder, this name will be followed by the tag “sync” or “notsync” to distinguish between pressure signals using a global reference time (“sync”) but contain leading/trailing zeros, that is, times when no signal is recorded at the respective receiver, or signals using a local reference time (“notsync”), that do only contain the usable part of each receivers signal.
<microphone_locations>: <name>; One or several .csv files which indicate microphone coordinates.; <output_path>; Indicates a folder where the results of the FW-H tool are written.