Model rotating wheels¶

Bramble models wheel rotation with a moving reference frame (MRF) region, called an RRF in the Template Case, or with a rotating-wall boundary condition. You set them up on the Template Case's Rotating tab.

Choose a method¶

Prepare the geometry¶

Tyre zones whose names match -tyre or -tire, such as fr-wh-tyre-lhs, get a rough-wall condition automatically. See toint zones.

Add a standard MRF¶

1. In the Template Case editor, go to the Rotating tab. In Rotating With RRF, click New.

2. Fill in the row:

   Field	Enter
   Name	The part of the MRF zone name after toint-rrf-. For the zone toint-rrf-fr-lhs, enter fr-lhs
   Regex	The zones to rotate, for example fr.*wh.*lhs
   Zoneless	Off
   Axis	The rotation axis vector
   Origin	A point on the axis (m)
   Omega	The rotational speed
   Mrf Point	A point inside the MRF region (m)
   Non-Rotating-Patches	Zones inside the MRF region that mustn't rotate, such as int- uprights and brake parts
   Tags	The wheel's kinematic tag, so the Kinematic Setup can fill in Axis, Origin and Omega (see below)

3. Click Save. Repeat for each wheel, then click Save in the header.

Let the Kinematic Setup set the rotation¶

When a Kinematic Setup's wheel model drives a row, it sets:

• Axis from the inboard to the outboard axle point
• Origin at the inboard axle point
• Omega from the velocity divided by the rolling radius (with crossflow, the velocity × cos(yaw))

The Kinematic Setup applies to rows whose Tags include <region>__<model name>, in lower case with spaces replaced by _, for example front_lhs__wheel. If no row has the tag, case creation fails.

To check the positions before you launch, use Validate on the Run's CFD Setup tab. With a Kinematic Setup loaded, it fills Origin from the inboard axle point and Mrf Point from the kinematic model's MRF point. It reports "No points matching: <name>", "No MRF point in kinematic setup for: <name>" or "No points in the kinematic setup" if it can't find them.

Use a zoneless MRF¶

1. In Rotating With RRF, click New and turn on Zoneless.
2. Fill in Name, Regex, Axis, Origin, Omega and Tags as for a standard MRF.
3. In Zoneless Patches, list the regexes of the zones that make up the rotating region, for example ["fr.*wh.*lhs"]. At least one is required. Non-Rotating-Patches and Mrf Point show N/A.
4. Click Save.

Zoneless MRFs:

• need a v1806F methodology ("Zoneless MRFs can only be used with the v1806F methodology.")
• can't be combined with a moving mesh

Add a rotating wall¶

1. On the Rotating tab, in Rotating Without RRF, click New.
2. Fill in Name, Regex (the zones to rotate), Axis, Origin (m), Omega and Tags.
3. Click Save.

Check the set-up¶

Pre-checks (see the checks reference):

To see each rotating region, choose Rotating: … in Select Pre-check Plots on the Run Checks tab. The Rotational Geometry Plots show the axis in red and the MRF point in green. Zoneless Patches Plots and Non-Rotating Patches Plots show the patch selections.

Solution checks:

Related: Template Case editor reference · Zone naming · Configure pre-checks · Checks reference