<sources>
This category specifies parameters for volumetric sources (and sinks) of the following kinds: <porous>, <turbulence>, <mrf>, and <acoustic>.
<sources> - <porous>
- Viscous coefficient.
- Inertial resistance coefficient.
For each porous medium, the text files uFX_porousMassFlow_Inst.txt and uFX_porousMassFlow_Avg.txt in the uFX_coefficientsData folder contain the instantaneous and averaged mass flow rates and the corresponding cross sections per porous medium (output at every coarsest iteration in ).
If a porous region is defined as isotropic (<porous_axis> is set to zero), the region is included in the file, but the mass flow rate cannot currently be evaluated. It is reported as zero.
- <name>
- Name of the instance (optional).
- <inertial_resistance>
- Inertial resistance (see Equation 1) of the instance in .
- <viscous_resistance>
- Viscous resistance (see Equation 1) of the instance in .
- <porous_axis>
- Flow direction through the instance. Crossflow that is not aligned with the porous axis is blocked. Its components are specified via the child parameters <x_dir>, <y_dir> and <z_dir>. If all components are set to zero, no preferred direction is used and the instance acts as an isotropic porous region, for example, bug screens.
- <parts>
- The closed volume(s) to which the volumetric body force should be applied and which are contained in the STL file must be specified via the child parameter <name> within the <parts> category, several volumes can be specified via repeated usage of <name> to assign the same properties to all of them. Additionally, if a closed volume consists of separate parts, they can also be specified via repeated usage of <name> to effectively form the closed volume. The specified names must exactly match the respective part names in the STL file.
<sources> - <turbulence>
This category contains all areas where synthetic turbulence is generated according to the so-called “vortex method.” 1
Currently, the turbulence generator adds turbulent structures for flows in positive x-direction only. It is set up by an x-position and the extents in y- and z-direction.
ultraFluidX automatically selects the corresponding voxel layer with a thickness of one voxel where the synthetic turbulence is added. All voxels of each turbulence instance are refined to the finest voxel size that is found in the instance.
- <name>
- (Optional) Name of the instance.
- <point>
-
- <x_pos>
- Global x-position of the turbulence generation zone.
- <bounding_box>
-
- <y_min>, <z_min>, <y_max>, <z_max>
- Extents of the turbulence generation zone in the global y- and z-direction.
- <num_eddies>
- Number of eddies that will be synthesized within the region in a pseudo-random manner. Should be in the order of 100-1000.
- <length_scale>
- Characteristic length scale for the synthetic turbulence in . Should be in the order of (or identical to) the voxel size in the turbulence generator region.
- <turbulence_intensity>
- Intensity of the synthetic turbulence, that is, ratio between root-mean-square of the turbulent velocity fluctuations and the mean velocity.
<sources> - <mrf>
- <name>
- (Optional) Name of the instance.
- <rpm>
- Rotational speed of the instance in [rpm] (revolutions per minute).
- <center>
- Center of rotation for each instance. Specified via the child parameters <x_pos>, <y_pos> and <z_pos> in .
- <axis>
- Rotational axis of the instance. Its direction (right-hand rule applies) must be specified via the child parameters <x_dir>, <y_dir> and <z_dir>.
- <parts>
- The closed volume(s) in which the MRF body force terms should be applied and which are contained in the STL file must be specified via the child parameter <name> within the <parts> category.
<sources> - <acoustic>
- <type>
- single_tone, broadband_noise.
- <amplitude>
- Amplitude of the noise source in .
- <frequency>
- Frequency of the single tone source in . Not applicable to broadband source.
- <num_avg_iterations>
- Specifies the number of iterations over which the broadband noise signal is averaged. You can specify fractions of 1 to obtain a signal at the desired sub-time step level corresponding to the resolution level in which the source is defined. Not applicable to single tone source.
- <position>
- Position of the acoustic source with the child parameters <x_pos>, <y_pos> and <z_pos> in .