Sweep
Select Sweep () from the Geometry toolbar to sweep one or several faces along a curve. Then enter the properties of the sweep operation using the following sections:
Cross Section
Select the faces you want to sweep in the Graphics window. The faces appear in the Faces to sweep list. Click the Active button to toggle between turning ON and OFF the Faces to sweep selections.
Select the Create cross-sectional faces check box (active by default) to make the sweep operation create cross-sectional faces between the sweep sections. Such cross-sectional faces can be useful, for example, for a swept mesh where you want to specify the mesh distribution for each section of the sweep.
Spine Curve
Select the edges you want to sweep along in the Graphics window. More than one edge can be selected, but the selected edges must form a nonclosed connected chain. The edges appear in the Edges to follow list. Click the Active button to toggle between turning ON and OFF the Edges to follow selections.
Select the Reverse direction check box to sweep in the negative edge direction.
The Smooth edge connections check box is selected by default. Clearing this check box means that transition zones are not added, which can give a better result in cases where the original edges already connect with a continuous tangent.
From the Parameterization list, select one of the following options:
Arc length (the default) to use a parameterization based on the arc length of the spine curve.
Normalized arc length to use a similar parameterization but with a normalized arc length (values 0–1). If it is more suitable to express the scale factor and the twist angle using the original parameter, you can use the normalized arc length parameterization instead of the default arc length parameterization.
Internal to use the parameterization that is stored in the geometry’s data structures. This is the parameterization used in earlier versions of COMSOL Multiphysics. It can also be useful if the edge that you sweep along do not need a parameterization, or a parameterization is unsuitable for that edge.
Keep Input
Select the Keep input objects check box to use the selected geometry objects for further geometry operations.
Select the Include all inputs in finalize operation check box to force the objects in the Face to sweep and Edges to follow lists to be included in the Form Union/Assembly operation. If the Include all inputs in finalize operation check box is not selected, these objects are not included in the Form Union/Assembly operation if the Face to sweep list or Edges to follow list contains all faces or edges in the objects.
Motion of Cross Section
This section contains a number of properties that determine how the face is transformed when swept along the spine curve.
A curve parameter name can be defined in the Parameter name field. Use this parameter in the expressions defining scale factor and twist angle. The parameter is increasing along the chain of edges to follow. It is not the same as the parameter s1 available in Results. For a single edge created by a Parametric Curve, the parameter is the same as the parameter used in the Parametric Curve.
The Scale factor field controls the size of the cross section face when swept along the spine curve.
The Twist angle field controls the rotation angle of the cross section face about the spine curve.
By default, twist compensation is active and prevents the twisting that would otherwise occur due to nonzero torsion for nonplanar curves. Clear the Twist compensation check box to turn off this compensation. When Twist compensation is active, it behaves as if a term was added to the Twist angle with a magnitude matching the integral of the torsion of the curve. This makes the edges in the sweep direction locally parallel to the spine curve. For a noncircular cross section, twist compensation also affects the shape of the generated object.
From the Face-spine alignment list, select an option to align the cross section to the spine curve:
Select No adjustment (the default) to sweep the face starting from its original position. Using this setting, it is possible to create sweeps where the face is not perpendicular to the spine curve, and where the face does not contain that starting point of the (possibly reversed) spine curve.
Select Adjust spine to adjust the spine curve so that it starts on the face to sweep and so that it is parallel to the face normal at the point where it touches the face. The first part of the spine curve is replaced by a cubic Bézier curve, with the length of the replaced part, measured in parameter values, controlled by the value in the Adjustment parameter length field.
Select Move face to move the face to the start of the (possibly reversed) spine curve and orient the face perpendicularly to the spine curve. This setting is only allowed when the face is located in a work plane, and the movement is such that the work plane origin coincides with the spine curve.
Advanced Settings
From the Geometry representation list, select Spline (the default) to represent the swept object using splines, or Bézier, to represent the swept object using Bézier curves. The difference is that using Bézier curves, the intersections between the surfaces that form the swept object are visible edges, whereas they are hidden when using splines.
The value in the Relative tolerance field is a relative tolerance that controls the accuracy of the geometric representation of the swept object. The geometric representation is an approximation, which is necessary because it is not possible to exactly represent a swept object using NURBS (nonuniform rational basis splines). The default value is 104 (0.01%).
Internally, the software represents the swept object by B-spline curves and surfaces, which are computed to approximate the mathematical definition of the swept surface. The number of knot points in the splines increases automatically until the approximation satisfies the tolerance specified in the Relative tolerance field or until it reaches the number of knots specified in the Maximum number of knots field (default value: 1000).
If more than one edge is selected in the Edges to follow list, the Direction-defining edge controls which edge is used to define the positive sweep direction. The Direction-defining edge is automatically set when the first edge is added to the Edges to follow list, so usually it does not have to be changed manually.
Selections of Resulting Entities
Select the Resulting objects selection check box to create predefined selections (for all levels — objects, domains, boundaries, edges, and points — that are applicable) in subsequent nodes in the geometry sequence. To also make all or one of the types of resulting entities (domains, boundaries, edges, and points) that the resulting objects consist of available as selections in all applicable selection lists (in physics and materials settings, for example), choose an option from the Show in physics (Show in instances if in a geometry part) list: All levels, Domain selection, Boundary selection, Edge selection, or Point selection. The default is Domain selection, which is suitable for use with materials and physics defined in domains. For use with a boundary condition, for example, choose Boundary selection. These selections do not appear as separate selection nodes in the model tree. Select Off to not make any selection available outside of the geometry sequence. From the Color list, choose a color for highlighting the resulting objects selection. See Selection Colors.
Cumulative Selection
If you want to make the resulting entities contribute to a cumulative selection, select a cumulative selection from the Contribute to list (the default, None, gives no contribution), or click the New button to create a new cumulative selection (see Cumulative Selections).
Assigned Attributes
From the Construction geometry list choose On to make the resulting objects available only in the feature’s geometry sequence. The default option Inherit means that the resulting objects become construction geometry if all input objects are construction geometry. Choose Off to never output construction geometry objects. For more information see Construction Geometry.