ParticlePhysics.h File Reference

Header file for Particle related physics modules. More...

#include <petsc.h>
#include <petscdmswarm.h>
#include <stdbool.h>
#include <petscsys.h>
#include <math.h>
#include "variables.h"
#include "logging.h"
#include "walkingsearch.h"

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Functions
PetscErrorCode	UpdateParticleField (const char *fieldName, PetscReal dt, PetscReal *psi_io, PetscReal diffusivity, PetscReal mean_val, PetscReal cell_vol, PetscReal C_model)
	Updates a single particle's field based on its state and physics model.
PetscErrorCode	UpdateFieldForAllParticles (UserCtx *user, const char *fieldName)
	Loops over all local particles and updates a specified field.
PetscErrorCode	UpdateAllParticleFields (UserCtx *user)
	Orchestrates the update of all physical properties for particles.

Detailed Description

Header file for Particle related physics modules.

This file contains declarations of functions responsible for solving for fields in the particle swarms within a simulation using PETSc's DMSwarm.

Definition in file ParticlePhysics.h.

Function Documentation

UpdateParticleField()

PetscErrorCode UpdateParticleField	(	const char *	fieldName,
		PetscReal	dt,
		PetscReal *	psi_io,
		PetscReal	diffusivity,
		PetscReal	mean_val,
		PetscReal	cell_vol,
		PetscReal	C_model
	)

Updates a single particle's field based on its state and physics model.

Implements the IEM (Interaction by Exchange with the Mean) model for scalar mixing. Physics: dPsi/dt = -Omega * (Psi - Psi_mean) Solution: Psi_new = Psi_mean + (Psi_old - Psi_mean) * exp(-Omega * dt)

Parameters

fieldName	Name
dt	Time
psi_io	Pointer
diffusivity	Particle
mean_val	Local
cell_vol	Volume
C_model	Model

Returns

PetscErrorCode 0 on success.

Updates a single particle's field based on its state and physics model.

Local to this translation unit.

Definition at line 14 of file ParticlePhysics.c.

{
    PetscFunctionBeginUser;
 
    if (strcmp(fieldName, "Psi") == 0) {
        if (cell_vol < 1.0e-14) cell_vol = 1.0e-14;
 
        PetscReal delta2 = PetscPowReal(cell_vol, 0.6666667);
        PetscReal omega = C_model * diffusivity / delta2;
        PetscReal decay = PetscExpReal(-omega * dt);
 
        PetscReal psi_old = *psi_io;
        *psi_io = mean_val + (psi_old - mean_val) * decay;
    }
 
    PetscFunctionReturn(0);
}

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UpdateFieldForAllParticles()

PetscErrorCode UpdateFieldForAllParticles	(	UserCtx *	user,
		const char *	fieldName
	)

Loops over all local particles and updates a specified field.

This function orchestrates the update of a single particle field across the entire local swarm. It gets access to the necessary particle data arrays and calls the UpdateParticleField kernel for each particle.

Parameters

[in,out]	user	Pointer to the UserCtx containing the swarm and simulation context.
[in]	fieldName	The name of the field to update (e.g., "Psi").

Returns

PetscErrorCode 0 on success.

Loops over all local particles and updates a specified field.

Local to this translation unit.

Definition at line 44 of file ParticlePhysics.c.

{
    PetscErrorCode ierr;
    DM             swarm = user->swarm;
    DM             da = user->da;
    PetscInt       n_local;
    PetscReal      dt = user->simCtx->dt;
    PetscReal      C_IEM = 2.0;
 
    PetscReal       *psi_arr = NULL;
    PetscReal       *diff_arr = NULL;
    PetscInt        *cell_arr = NULL;
 
    PetscReal       ***grid_mean = NULL;
    PetscReal       ***grid_aj = NULL;
 
    PetscBool       accessed_eulerian = PETSC_FALSE;
 
    PetscFunctionBeginUser;
    PROFILE_FUNCTION_BEGIN;
 
    ierr = DMSwarmGetLocalSize(swarm, &n_local); CHKERRQ(ierr);
    if (n_local == 0) {
        PetscFunctionReturn(0);
    }
 
    ierr = DMSwarmGetField(swarm, fieldName, NULL, NULL, (void**)&psi_arr); CHKERRQ(ierr);
 
    if (strcmp(fieldName, "Psi") == 0) {
        ierr = DMSwarmGetField(swarm, "Diffusivity", NULL, NULL, (void**)&diff_arr); CHKERRQ(ierr);
        ierr = DMSwarmGetField(swarm, "DMSwarm_CellID", NULL, NULL, (void**)&cell_arr); CHKERRQ(ierr);
 
        if (!user->lPsi || !user->lAj) {
             SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "UserCtx lPsi or lAj not initialized.");
        }
 
        ierr = DMDAVecGetArrayRead(da, user->lPsi, &grid_mean); CHKERRQ(ierr);
        ierr = DMDAVecGetArrayRead(da, user->lAj,  &grid_aj);   CHKERRQ(ierr);
        accessed_eulerian = PETSC_TRUE;
    }
 
    for (PetscInt p = 0; p < n_local; ++p) {
        PetscReal p_diff = 0.0;
        PetscReal p_mean = 0.0;
        PetscReal p_vol  = 1.0;
 
        if (strcmp(fieldName, "Psi") == 0) {
            PetscInt i = cell_arr[3*p + 0];
            PetscInt j = cell_arr[3*p + 1];
            PetscInt k = cell_arr[3*p + 2];
 
            p_diff = diff_arr[p];
            p_mean = grid_mean[k][j][i];
 
            PetscReal jac = grid_aj[k][j][i];
            p_vol = (jac > 1.0e-14) ? (1.0 / jac) : 1.0e-14;
        }
 
        ierr = UpdateParticleField(fieldName, dt, &psi_arr[p], p_diff, p_mean, p_vol, C_IEM);
        CHKERRQ(ierr);
    }
 
    ierr = DMSwarmRestoreField(swarm, fieldName, NULL, NULL, (void**)&psi_arr); CHKERRQ(ierr);
 
    if (strcmp(fieldName, "Psi") == 0) {
        ierr = DMSwarmRestoreField(swarm, "Diffusivity", NULL, NULL, (void**)&diff_arr); CHKERRQ(ierr);
        ierr = DMSwarmRestoreField(swarm, "DMSwarm_CellID", NULL, NULL, (void**)&cell_arr); CHKERRQ(ierr);
    }
 
    if (accessed_eulerian) {
        ierr = DMDAVecRestoreArrayRead(da, user->lPsi, &grid_mean); CHKERRQ(ierr);
        ierr = DMDAVecRestoreArrayRead(da, user->lAj,  &grid_aj);   CHKERRQ(ierr);
    }
 
    LOG_ALLOW(GLOBAL, LOG_INFO, "Updated particle physics for field '%s'.\n", fieldName);
 
    PROFILE_FUNCTION_END;
    PetscFunctionReturn(0);
}

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UpdateAllParticleFields()

PetscErrorCode UpdateAllParticleFields

(

UserCtx *

user

)

Orchestrates the update of all physical properties for particles.

This function serves as the top-level entry point for updating particle-specific physical quantities after their position and the surrounding fluid velocity are known. It calls a sequence of more specific update routines for each property.

For example, it can be configured to update:

• Particle kinetic energy (stored in "Psi")
• Particle accumulated shear stress
• Particle temperature
• etc.

Parameters

[in,out]

user

Pointer to the UserCtx containing the swarm and simulation context.

Returns

PetscErrorCode 0 on success.

Orchestrates the update of all physical properties for particles.

Full API contract (arguments, ownership, side effects) is documented with the header declaration in include/ParticlePhysics.h.

See also

UpdateAllParticleFields()

Definition at line 132 of file ParticlePhysics.c.

{
    PetscErrorCode ierr;
    PetscFunctionBeginUser;
    PROFILE_FUNCTION_BEGIN;
 
    LOG_ALLOW(GLOBAL, LOG_INFO, "Updating all particle physical properties...\n");
 
    if (VerificationScalarOverrideActive(user->simCtx)) {
        ierr = ApplyVerificationScalarOverrideToParticles(user); CHKERRQ(ierr);
        LOG_ALLOW(GLOBAL, LOG_INFO, "Verification scalar override active; skipped model-driven Psi update.\n");
        PROFILE_FUNCTION_END;
        PetscFunctionReturn(0);
    }
 
    ierr = UpdateFieldForAllParticles(user, "Psi"); CHKERRQ(ierr);
 
    LOG_ALLOW(GLOBAL, LOG_INFO, "All particle physical properties updated.\n");
 
    PROFILE_FUNCTION_END;
    PetscFunctionReturn(0);
}

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