simulationCases/jumpingDrops_main.c

Jumping Drops - Main Simulation Phase

Runs the full drop dynamics simulation from the initial condition created by the initialization phase. This version is MPI-compatible for parallel execution.

Usage

./jumpingDrops_main [case.params]

Example (parallel with MPI):

mpirun -np 8 ./jumpingDrops_main case.params

Inputs

case.params: runtime parameter file with tmax, Oh, Bo, and MAXlevel
dump or dumpInit: Binary dump file from initialization phase (must exist)

Outputs

dump: Current simulation state (overwritten at each snapshot)
intermediate/snapshot-*.dump: Periodic snapshots for post-processing
log: Time series of kinetic energy and center-of-mass velocity

Dependencies

This file does not include distance.h, making it MPI-compatible. Use mpirun or srun for parallel execution on HPC systems.

MPI Configuration

The MPI_MODE macro is defined before including the common header to enable MPI-aware logging (only rank 0 writes to files).

Author

Vatsal Sanjay ([email protected])
CoMPhy Lab, Durham University
Last updated: 2026-01-30

#define MPI_MODE

Common Definitions

Includes shared constants, tolerances, and helper functions.

#include "jumpingDrops_common.h"
#include "params.h"

Global Variable Definitions

Runtime parameters set from command-line arguments.

double tmax, Oh, Bo;
int MAXlevel;

Main Function

Loads runtime parameters from case.params, sets fluid properties, and starts the main simulation run.

int main(int argc, char *argv[]) {
  if (!params_init_from_argv(argc, argv)) {
    fprintf(ferr, "Usage: %s [case.params]\n", argv[0]);
    return 1;
  }

  tmax = param_double("tmax", 10.0);
  Oh = param_double("Oh", 1e-3);
  Bo = param_double("Bo", 1e-3);
  MAXlevel = param_int("MAXlevel", 10);

  // Initialize grid
  init_grid (1 << MINlevel);
  L0 = Ldomain;

  fprintf(ferr, "==============================================\n");
  fprintf(ferr, "Jumping drops - Main Simulation Phase\n");
  fprintf(ferr, "==============================================\n");
  fprintf(ferr, "Parameter file = %s\n", params_source_path());
  fprintf(ferr, "tmax = %g\n", tmax);
  fprintf(ferr, "Oh = %g\n", Oh);
  fprintf(ferr, "Bo = %g\n", Bo);
  fprintf(ferr, "MAXlevel = %d\n", MAXlevel);
#ifdef _MPI
  fprintf(ferr, "MPI enabled: %d processes\n", npe());
#endif
  fprintf(ferr, "==============================================\n\n");

  // Set fluid properties
  rho1 = 1.0;                         // liquid density (normalized)
  mu1 = Oh;                           // liquid viscosity
  rho2 = Rho21;                       // gas density
  mu2 = Mu21*Oh;                      // gas viscosity (consistent with init)
  f.sigma = 1.0;                      // surface tension (normalized)
  G.y = -Bo;                          // gravity (CRITICAL FIX: was missing!)

  // Create intermediate directory for snapshots
  char comm[80];
  sprintf (comm, "mkdir -p intermediate");
  system(comm);

  // Start simulation
  run();
}

Initialization Event

Restores simulation state from dump or dumpInit file created by the initialization phase. Fails with an error message if no dump file is found.

event init(t = 0){
  if(!restore (file = "dump")){
    fprintf(ferr, "ERROR: Cannot restore from dump file\n");
    fprintf(ferr, "Make sure dumpInit exists from initialization phase\n");
    fprintf(ferr, "Run jumpingDrops_init.c first to create initial condition\n");
    return 1;
  }
  fprintf(ferr, "Successfully restored from dump file\n");
}