Parameters

YAML and Directory Structure

The YAML structure below details all possible parameters, their expected data types, and input formats.

filetype: string
domain:
  terrain_path: string
  x_range: [double, double]
  y_range: [double, double]
  height: double
  aspect_ratio: int
  upper_aspect_ratio: double
  aspect_distance: double
  dimension: int
  inflow_angle: double
  type: string
  center: [double, double]
  radius: double
refine:
  global_scale: double
  background_length_scale: double
  farm:
    type: string
    length_scale: double
    threshold_distance: double
  turbine:
    type: string
    length_scale: double
    threshold_upstream_distance: double
    threshold_downstream_distance: double
    threshold_rotor_distance: double
    num_turbines: int
    1:
      x: double
      y: double
      HH: double
    2:
      x: double
      y: double
      HH: double

      # ...

    n:
      x: double
      y: double
      HH: double
refine_custom:
  num_refines: int
  1:
    type: string
    x_range: [double, double] or double
    y_range: [double, double] or double
    z_range: [double, double]
    radius: double
    length_scale: double

    # ...

  n:
    type: string
    x_range: [double, double] or double
    y_range: [double, double] or double
    z_range: [double, double]
    radius: double
    length_scale: double

Parameter Descriptions

The schema above contains domain and refinement parameters. The following sections will describe the domain and refinement customizability offered by AeroMesh, as well as some different options offered in 3D and 2D meshes that can provide additional flexibility.

Domain Parameters

This section details the parameters that define the domain for both 2D and 3D simulations. These parameters are not optional and must be included in every meshing procedure.

Parameter	Description	Optional
type	Box by default. Can be set to cylinder for a cylindrical outer domain (or a circle in 2D).	Yes.
x_range	The minimum and maximum x-coordinates that define the meshing domain.	No.
y_range	The minimum and maximum y-coordinates that define the meshing domain.	No.
dimension	The dimension of the mesh. 2 for 2D meshes, 3 for 3D meshes.	No.
inflow_angle	If there is one incoming wind vector, this flag will orient the turbines to face the wind. Input the angle in degrees.	Yes.

Refinement Parameters

There are a few parameters that apply globally across refinements. This section details them.

Parameter	Description	Optional
global_scale	A scaling factor applied uniformly to all length scales. 1 by default, to create no effect.	Yes.
background_length_scale	The length scale of the meshing across the entire domain.	No.

Creating Turbines

The number of turbines must be specified using the appropriate (num_turbines) field. For each turbine, create a numerical field and populate it with the three relevant turbine parameters. Examples are shown here, under the turbine header. The table below describes the three turbine parameters.

Parameter	Description	Optional
x	The x-coordinate of the center of the turbine.	No.
y	The y-coordinate of the center of the turbine.	No.
HH	The turbine’s hub height. This parameter determines how high off the terrain the turbine center is placed. Set to 100 by default.	Yes.

Creating Turbines

In addition to defining the location of the farm’s turbines, AeroMesh provides additional global customizability that applies to every turbine in the mesh. These options are described below.

Parameter	Description	Optional
num_turbines	The expected number of turbines.	No.
length_scale (turbine)	The length scale of the meshing near the turbines.	No.
threshold_upstream_distance	The extent to which the turbine meshes should extend in the negative wake direction.	No.
threshold_downstream_distance	The extent to which the turbine meshes should extend in the positive wake direction.	No.
threshold_rotor_distance	The radius formed by a rotation of the turbine’s rotor.	No.

Creating Farm Refinements

AeroMesh defines a “farm” as, at a minimum, a bounding geometry that surrounds all the turbines and an associated length scale for this region. Note that farms are optional and do not need to be included in the YAML if not desired. Examples are shown here, under the farm header. The table below describes the farm parameters.

Parameter	Description	Optional
type	None (disabled) by default. Can be set to cylinder or box if desired.	Yes.
threshold_distance	By default, a farm region is defined by a minimum bounding rectangle surrounding all the turbines. This parameter extends the bounding region by its value.	Yes.
length_scale	The length scale of the points contained within the farms.	Yes.

Creating Custom Refinements

Creating custom refinements is almost identical to creating turbines. The number of custom refinements must be specified. Depending on the type of refinement (box or cylinder) desired, different parameters must be supplied. In 2D meshes, the 3D refinement types will be replaced with their 2D analogs without the need for any flags from the user. Examples are shown here, under the refine_custom header. The table below describes the relevant sub-parameters.

Parameter	Description	Optional
type	Either “box” for a box refine or “cylinder” for a cylindrical one.	No.
x_range	In box refines, the x range of the refinement. In cylinders, the x-coordinate of the center.	No.
y_range	In box refines, the y range of the refinement. In cylinders, the y-coordinate of the center.	No.
z_range	The z range of the refinement.	No.
radius	The radius of a cylindrical refinement. Unused by box meshes and does not need to be included.	No.
length_scale	The length scale across the custom refinement.	No.

3D Domain Customizability

3D meshes have some additional domain-level parameters not available in 2 dimensions. These parameters are described below.

Parameter	Description	Optional
terrain_path	The path to a file containing valid terrain data, where the terrain is a function f(x, y) = z. If omitted, the domain will have a smooth bottom face.	Yes.
height	The extension of the wind farm in the z-direction.	No.
aspect_ratio	The ratio of nodes in the z-direction to nodes in the x-y plane. Used to create anisotropic effects, if desired.	Yes.
upper_aspect_ratio	Similar to aspect_ratio, but applied above the threshold distance instead to create expanded nodes in the z-direction. Note that the resultant size after the application of both aspect ratios must be at least the original height of the domain to prevent undefined behavior.	Yes.
aspect_distance	The z-distance up to which the anisotropic effects generated by aspect_ratio will extend.	Yes.

2D Turbine Customizability

In 2D meshes, the type of refinement that defines the turbine may be specified. This customizability is done using the refine[turbine][type] flag. The table below describes the flag.

Parameter	Description	Optional
type	Determines whether turbines are meshed using a rectangular wake or as a large circle. The options are rectangle and circle respectively. Rectangles are used by default.	Yes.

Output Format

AeroMesh produces an output file named out.extension that contains the mesh data. The extension type can be controlled by the “filetype” field. By default, AeroMesh produces msh files. However, it supports any other data formats handled by GMSH and the additional xdmf output type if desired.