# Initial Conditions¶

Tools for the creation of initial conditions are available via the WoMa and SEAGen open-source python packages, including: creating spherical or spinning planetary (or similar) profiles; placing particles to match arbitrary profiles with precise SPH densities; and setting the initial target and impactor positions and velocities, as presented in Kegerreis et al. (2019) and Ruiz-Bonilla et al. (2020).

They are available with documentation and examples at https://github.com/srbonilla/WoMa and https://github.com/jkeger/seagen, or can be installed directly with pip (https://pypi.org/project/woma/, https://pypi.org/project/seagen/).

## Settling initial conditions with fixed entropies¶

If the particles’ equations of state include specific entropies, and the initial conditions file includes specific entropies for each particle (in PartType0/Entropies), then configuring SWIFT with --enable-planetary-fixed-entropy will override the internal energy of each particle each step such that its specific entropy remains constant.

This should be used with caution, but may be a convenient way to maintain an entropy profile while initial conditions settle to equilibrium with their slightly different SPH densities.