ludwig-cf/ludwig: Ludwig 0.21.0

Release 0.21.0 (9th January 2024)

• Ellipsoids. A feature which allows ellipsoidal particles to be used has been added by Sumesh Thampi.

• "colloid_type" has been split into a number of more general properties including: boundary condition (bc) either bbl or subgrid; shale either "disk", "sphere", or "ellipsoid"; active (logical); magnetic (logical). The default is: bc = bbl, shape = sphere, active = no, magnetic = no. There are some conditions, e.g., "disk" expects a 2D D2Q9 model. This affects the way colloid details are specified in the input. Older colloid state files should still work. See https://ludwig.epcc.ed.ac.uk

• There is no longer an option available for field halo swaps; the scheme has been consolidated is always the same (for CPU). GPU run time configuration is pending. Halo information is still available https://ludwig.epcc.ed.ac.uk/inputs/parallel.html

• If you use a 2-dimensional system (L_z = 1) with an order parameter, you must use a 2d gradient calculation. This is related to the (non-) treatment of halo swaps in the third dimension for fields.

• A colloid_buoyancy option has been added which is similar to colloid_gravity but computes a force proportional to colloid volume. See https://ludwig.epcc.ed.ac.uk/inputs/colloid.html#external-forces

Bug fixes:

• Issue 270: a colloid with an initial position placed exactly at a sub-domain boundary can fail to be attached to the cell list in some circumstances causing a crash. This has been fixed by adding a small position adjustment, or if this doesn't work, failing with a message.
• Issue 268: if using wetting information read from porous media files, the form of the key words in the input file has been adjusted. See https://ludwig.epcc.ed.ac.uk/inputs/porous.html