Sizing

PyPrimeMesh provides various sizing controls to help you define how the mesh size is distributed on a surface or within the volume.

Sizing control

Mesh quality and resolution are important factors for capturing physics accurately and efficiently. Size controls allows you to get the desired mesh distribution. PyPrimeMesh specifies the sizing requirements using sizing controls. The sizing controls in PyPrimeMesh have the following:

• Scope

• Maximum rate of change of size

• Range within which the sizes should be on or within the scope

The SizingType class has control types for defining sizing requirements:

• Curvature

• Proximity

• Hard

• Soft

• Meshed

• Body of influence

Curvature sizing

In the SizingType class, selecting the CURVATURE parameter sizes based on the scope on the local curvature. The size is small when the local curvature is large and vice versa. This code shows how to use the CurvatureSizingParams class to specify the minimum and maximum size, growth rate, and normal angle:

size_control = model.control_data.create_size_control(prime.SizingType.CURVATURE)
size_control.set_curvature_sizing_params(
    prime.CurvatureSizingParams(model=model, min=0.2, max=2.0, growth_rate=1.2)
)
size_control.set_suggested_name("curv_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

The normal angle parameter is the maximum allowable angle that one element edge may span. For example, a value of 5 implies that a division are made when the angle change along the curve is 5 degrees. Hence, a 90 degree arc is divided into approximately 18 segments.

Proximity sizing

In the SizingType class, selecting the PROXIMITY parameter sizes based on the closeness of the surfaces or edges specified in the scope. This code shows how to use the ProximitySizingParams class to specify the minimum and maximum size, growth rate, and the number of element per gap:

size_control = model.control_data.create_size_control(prime.SizingType.PROXIMITY)
size_control.set_proximity_sizing_params(
    prime.ProximitySizingParams(
        model=model,
        min=0.1,
        max=2.0,
        growth_rate=1.2,
        elements_per_gap=3.0,
        ignore_orientation=True,
        ignore_self_proximity=False,
    )
)
size_control.set_suggested_name("prox_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

The ignore_self_proximity and ignore_orientation parameters are also considered for proximity sizing. The ignore_self_proximity parameter is set to True if proximity between faces in the same face zonelet is to be ignored. The ignore_orientation parameter allows you to ignore the face normal orientation during the proximity calculation. This Boolean parameter is set to False by default. In general, the proximity depends on the direction of face normals.

This example explains the use of the ignore_orientation parameter for face proximity. The normals on the grooved box point inward. With the default setting of False, the proximity size function does not refine the surface along the entire groove length. If the ignore_orientation is set to True, the surface is refined along the groove length

Hard sizing

In the SizingType class, selecting the HARD parameter sizes on the scope based on a uniform value while meshing. This code shows how to use the HardSizingParams class to specify the minimum size and growth rate:

size_control = model.control_data.create_size_control(prime.SizingType.HARD)
size_control.set_hard_sizing_params(
    prime.HardSizingParams(model=model, min=0.2, growth_rate=1.2)
)
size_control.set_suggested_name("hard_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

Soft sizing

In the SizingType class, selecting the SOFT parameter sizes on the scope based on a certain maximum value that should not be exceeded while meshing. This code shows how to use the SoftSizingParams class to specify the maximum size and growth rate:

size_control = model.control_data.create_size_control(prime.SizingType.SOFT)
size_control.set_soft_sizing_params(
    prime.SoftSizingParams(model=model, max=0.2, growth_rate=1.2)
)
size_control.set_suggested_name("soft_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

Meshed sizing

In the SizingType class, selecting the MESHED parameter sizes based on existing local sizes. This example shows how to use the MeshedSizingParams class to specify the growth rate:

size_control = model.control_data.create_size_control(prime.SizingType.MESHED)
size_control.set_meshed_sizing_params(
    prime.MeshedSizingParams(model=model, growth_rate=1.2)
)
size_control.set_suggested_name("meshed_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

Body of influence sizing

In the SizingType class, selecting the BOI parameter sizes inside a closed volume scope that is not to exceed a certain maximum value. This code shows how to use the BoiSizingParams class to specify the maximum size and growth rate:

size_control = model.control_data.create_size_control(prime.SizingType.BOI)
size_control.set_boi_sizing_params(
    prime.BoiSizingParams(model=model, max=20.0, growth_rate=1.2)
)
size_control.set_suggested_name("BOI_control")
size_control.set_scope(prime.ScopeDefinition(model=model))

Size fields

The SizeFieldType class helps you to fetch the element size at a given location. These size field types are available in PyPrimeMesh:

• Constant

• Volumetric

• Geodesic

• Geometric

• Meshedgeodesic

The Volumetric and Geodesic size fields can process and respect the size control that you define. The Volumetric size field can be computed using the Compute volumetric method and then surface and volume meshing can be applied. The remaining size field types are computed as part of various surface and volume meshing operations.

Constant size field

In the SizeFieldType class, selecting the CONSTANT parameter computes the size field based on the size controls specified.

Volumetric size field

In the SizeFieldType class, selecting the VOLUMETRIC parameter computes the size field based on the size controls specified.

Geodesic size field

In the SizeFieldType class, selecting the GEODESIC parameter computes the size field on face nodes based on the size controls specified. Sizes are defined along a surface rather than the volume. Geodesic sizing enables you to confine sizes to surfaces and avoid problems like dead space refinement.

Geometric size field

In the SizeFieldType class, selecting the GEOMETRIC parameter computes the size field based on existing boundary sizes. Sizes can gradually increase from the minimum size to the maximum size based on the growth rate.

Meshedgeodesic size field

In the SizeFieldType class, selecting the MESHEDGEODESIC parameter computes the size field using average mesh edge lengths and is diffused geodesical.