Cylinder

A cylinder is a three-dimensional geometric shape with a circular cross-section, defined by its center, axis direction, height, and radius.

Available Options

Option	Description	Applicable
Name	Identifier for the cylinder	always
Center	Three-dimensional coordinates of the center point	always
Axis	Direction vector defining the cylinder orientation	always
Radius	Distance from central axis to outer surface	always
Inner radius	Distance from central axis to inner surface	always
Height	Length along the central axis	always

Detailed Descriptions

Name

Identifier for the cylinder volume entity.

• Required

Note: Names are not required to be unique, but using descriptive unique names is recommended.

Center

Three-dimensional coordinates (X, Y, Z) defining the center point of the cylinder.

• Required

• Units: Length

Note: The center is located at the midpoint of the cylinder’s height.

Axis

Direction vector (X, Y, Z) defining the orientation of the cylinder’s central axis.

• Required

Notes:

• The vector is normalized internally

• The height extends equally in both directions from the center along this axis

Radius

The distance from the central axis to the outer cylindrical surface.

• Required

• Units: Length

Inner radius

The distance from the central axis to the inner cylindrical surface, creating a hollow cylinder (annulus).

• Default: 0 (solid cylinder)

• Units: Length

Notes:

• Set to 0 for a solid cylinder

• Must be less than the radius

• Use non-zero values to create donut-shaped (annular) volumes

Height

The total length of the cylinder along its central axis.

• Required

• Units: Length

Note: The cylinder extends height/2 in each direction from the center along the axis.

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❓ Frequently Asked Questions

• How do I create a hollow cylinder?

  Set the inner radius parameter to a value greater than 0 and less than the outer radius.

• Where is the center located relative to the cylinder?

  The center is at the geometric center of the cylinder, midway along its height.

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🐍 Python Example Usage

See also

Cylinder

import flow360 as fl

# Solid cylinder for a rotor disk
rotor_cylinder = fl.Cylinder(
    name="rotor_zone",
    center=(0, 0, 0) * fl.u.m,
    axis=(0, 0, 1),
    outer_radius=1.5 * fl.u.m,
    height=0.2 * fl.u.m
)

# Hollow cylinder (annulus) excluding a hub
annular_cylinder = fl.Cylinder(
    name="propeller_zone",
    center=(0, 0, 0) * fl.u.inch,
    axis=(1, 0, 0),
    outer_radius=12 * fl.u.inch,
    inner_radius=2 * fl.u.inch,
    height=3 * fl.u.inch
)