# Including Rotation

This chapter briefly discusses how to include rotation effects in GYRE calculations. Further details of GYRE’s treatment of rotation are presented in the Rotation Effects section.

## Setting the Rotation Rate

There are two different ways to define the rotation angular velocity
\(\Omega\), via parameters in the `&rot`

namelist group.

If

`Omega_rot_source`

=`MODEL`

, then differential rotation is assumed with a spatially varying \(\Omega\) obtained from the stellar model. If the model doesn’t have this capability (see the Model Capabilities section), then \(\Omega\) is set to zero throughout the star.If

`Omega_rot_source`

=`UNIFORM`

, then uniform rotation is assumed with a spatially constant \(\Omega\) set by the`Omega_rot`

and`Omega_rot_units`

parameters.

## Enabling Doppler Effects

Doppler effects are enabled by default whenever calculations are
performed with non-zero \(\Omega\) and mode azimuthal order
\(m\). To disable these effects, set `m`

= `0`

in
the `&mode`

namelist group.

## Enabling Coriolis Effects

Coriolis effects are disabled by default, but can be enabled using the
traditional approximation of rotation (TAR) by setting
`coriolis_method`

=`'TAR'`

in the `&rot`

namelist group. The solution family is controlled by the
`rossby`

parameter of the `&rot`

namelist group; set to
`.TRUE.`

for the Rossby family, and to `.FALSE.`

(the
default) for the gravito-acoustic family.