picsolver.c

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/**
 * @file main.c
 * @brief Main driver for the unified CFD and Lagrangian particle solver.
 *
 * This version focuses on establishing the core architecture for a particle-coupled
 * flow simulation. It initializes the grid, solver objects, and a DMSwarm of
 * Lagrangian particles. Hooks for the Immersed Boundary Method (IBM) are present
 * but are currently inactive to allow for iterative development.
 *
 * ARCHITECTURE:
 * 1. A central `SimulationContext` (simCtx) holds all simulation-wide configuration.
 * 2. `CreateSimulationContext()` handles all command-line parsing.
 * 3. The `main()` function provides a high-level workflow for the simulation.
 */
 
#include "simulation.h" // The new, unified header file
 
/*================================================================================*
 *                           MAIN FUNCTION                                        *
 *================================================================================*/
 
#undef __FUNCT__
#define __FUNCT__ "main"
int main(int argc, char **argv)
{
  PetscErrorCode    ierr;
  SimCtx *simCtx = NULL; // The single, top-level context object
 
  // === I. INITIALIZE =======================================================
  ierr = PetscInitialize(&argc, &argv, (char *)0, "PIC-Solver"); CHKERRQ(ierr);
 
  // === II. CONFIGURE =======================================================
  // Create and populate the entire simulation configuration from command line.
  ierr = CreateSimulationContext(argc, argv, &simCtx); CHKERRQ(ierr);
  // == IIB. SET EXECUTION MODE (SOLVER vs POST-PROCESSOR) =====
  simCtx->exec_mode = EXEC_MODE_SOLVER;
  // == IIC. CONFIGURE SIMULATION ENVIRONMENT & DIRECTORIES =====
  ierr = SetupSimulationEnvironment(simCtx); CHKERRQ(ierr);
  
  // === III. SETUP ==========================================================
  // Build the simulation environment step-by-step.
 
  // 1. Setup the multi-grid hierarchy, DMs, and PETSc vectors/solvers.
  ierr = SetupGridAndSolvers(simCtx); CHKERRQ(ierr);
 
  // 2. Setup the boundary condition handlers for the flow solver.
  ierr = SetupBoundaryConditions(simCtx); CHKERRQ(ierr);
 
  // 3. Setup domain decomposition info needed for particle migration.
  ierr = SetupDomainRankInfo(simCtx); CHKERRQ(ierr);
 
  // 4. Setup Initial State of Eulerian Fields
  ierr = InitializeEulerianState(simCtx); CHKERRQ(ierr);
 
  // 5. If requested, initialize the Lagrangian Particle Swarm.
  if (simCtx->np > 0) {
    ierr = InitializeParticleSwarm(simCtx); CHKERRQ(ierr);
    }
 
  LOG_ALLOW(GLOBAL,LOG_INFO," Setup Completed.\n");
  
  
  /*
    * --- IBM/FSI FEATURE HOOK (Currently Inactive) ---
    * The logic for initializing immersed bodies would be enabled here.
    * The `-immersed` command-line flag would control this block.
    *
  if (simCtx->immersed) {
      ierr = InitializeImmersedBoundary(simCtx); CHKERRQ(ierr);
  }
  */
 
  // === IV. EXECUTE =========================================================
  // Display a summary banner and run the main time-stepping loop.
 
  ierr = DisplayBanner(simCtx); CHKERRQ(ierr);
 
  if (!simCtx->OnlySetup) {
      // This function will contain the main time loop, orchestrating
      // the flow solve and particle advection steps.
 
    if(simCtx->StartStep == 0){
        if(simCtx->np>0){
        ierr = PerformInitializedParticleSetup(simCtx); CHKERRQ(ierr);
      }else{ 
        // Write the initial Eulerian fields.
        UserCtx *user = simCtx->usermg.mgctx[simCtx->usermg.mglevels-1].user;
        for(PetscInt bi = 0; bi < simCtx->block_number; bi++){
          ierr = WriteSimulationFields(&user[bi]);
        }
      }
    }else{
      ierr = FinalizeRestartState(simCtx); CHKERRQ(ierr);
    }
 
    //********************PROFILING ROUTINES ****************************
    // Before the first step, clear all counters accumulated during setup
    // to ensure the Timestep 1 profile is clean.
    ierr = ProfilingLogTimestepSummary(simCtx->step);
    ierr = ProfilingResetTimestepCounters(); CHKERRQ(ierr);
    //*******************************************************************
 
    if(simCtx->StepsToRun > 0){
      ierr = AdvanceSimulation(simCtx); CHKERRQ(ierr);
    }else{
      LOG_ALLOW(GLOBAL,LOG_INFO,"Initial setup complete.No steps to run.Exiting!.\n");
    }
  }else{
    LOG_ALLOW(GLOBAL,LOG_INFO,"SETUP ONLY MODE enabled. Skipping time loop.\n");
  }
 
  // == V. REPORT FIELDS ===========================
 
  // === V. FINALIZE =========================================================
  // Cleanly destroy all objects and free all memory.
 
  ierr = ProfilingFinalize(simCtx); CHKERRQ(ierr);
  // ierr = FinalizeSimulation(simCtx); CHKERRQ(ierr);
  ierr = PetscFinalize();
 
  return ierr;
}