Active drops with memory

Open Basilisk C implementation of planar chemically fuelled active drops. The solver couples a CLSVOF interface, incompressible flow, interfacial chemical production, advection--diffusion and concentration-dependent surface tension. It supports one, two or four drops, runtime parameter files and checkpoint restart.

Requirements

• Basilisk with qcc
• A C compiler and standard maths library
• MPI for parallel builds

The repository includes the local activity model in src-local/activity.h. The benchmark solver uses Basilisk's upstream two-phase-clsvof.h; src-local/two-phase-clsvof-VP.h is an experimental viscoplastic extension and is not included by dropMove.c.

Build

Serial:

qcc -O2 -Wall -disable-dimensions dropMove.c -o dropMove -lm

MPI:

CC99=mpicc qcc -O2 -Wall -D_MPI=1 -disable-dimensions \
  dropMove.c -o dropMove -lm

Run

Use a supplied parameter file:

./dropMove --params parameters/single-drop.cfg
./dropMove --params parameters/two-drop.cfg
./dropMove --params parameters/four-drop.cfg

Command-line key=value arguments override values loaded earlier:

./dropMove --params parameters/four-drop.cfg max_level=14 tmax=2 \
  output_dir=output/smoke

Supported keys are Oh, Ca, Pe, AcNum, domain, max_level, min_level, tmax, tsnap, drops, drops_x, drops_y, drop_radius, drop_spacing, ke_limit, movement_threshold, output_dir, restart_file and resume. The drops shorthand accepts 1, 2 or 4; drops_x and drops_y define larger rectangular arrays for scale-up studies. For compatibility with the original Péclet-number scan, a single positional number is interpreted as Pe.

The supplied files demonstrate the one-, two- and four-drop initialisations. The four-drop file is the large-domain benchmark starting point; its resolution and domain should be increased together when constructing larger physical scale-up cases.

Restart

Each output event writes a rolling checkpoint at <output_dir>/restart. Resume without deleting previous snapshots using:

./dropMove --params parameters/four-drop.cfg resume=1

Set restart_file=/path/to/checkpoint to resume from another checkpoint. Only MPI rank zero creates the output directory; all ranks participate in parallel dump() and restore(). A resumed job must use the same physical parameters as the job that wrote the checkpoint.

Output and post-processing

Snapshots and log.dat are written below output_dir. The postProcess-contour/ and postProcess-vectors/ directories contain source and Python scripts for extracting interface and velocity data. Generated binaries, simulation output and macOS metadata are ignored.

Licence

GPL-3.0. See LICENSE.