integration.cpp File Reference

functions for integration of particle trajectories More...

#include "core_mesh.h"
#include "core_power.h"
#include "integration.hpp"
#include "params.hpp"

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Functions
void	stream_step (const double da, std::vector< Particle_v< double >> &particles)
void	stream_kick_stream (const double da, std::vector< Particle_v< double >> &particles, std::function< void()> kick_step, size_t per)
void	kick_step_no_momentum (const Cosmo_Param &cosmo, const double a, std::vector< Particle_v< double >> &particles, const std::vector< Mesh > &vel_field)
void	kick_step_w_momentum (const Cosmo_Param &cosmo, const double a, const double da, std::vector< Particle_v< double >> &particles, const std::vector< Mesh > &force_field)
void	kick_step_w_momentum_pm (const Cosmo_Param &cosmo, const double a, const double da, std::vector< Particle_v< double >> &particles, const std::vector< Mesh > &force_field)

Detailed Description

functions for integration of particle trajectories

Author

Michal Vrastil

Date

2018-07-11

Definition in file integration.cpp.

Function Documentation

void kick_step_no_momentum	(	const Cosmo_Param &	cosmo,
		const double	a,
		std::vector< Particle_v< double >> &	particles,
		const std::vector< Mesh > &	vel_field
	)

Definition at line 32 of file integration.cpp.

References assign_from(), and growth_change().

Referenced by App_Var_FF::upd_pos().

{
    // no memory of previus velocity, 1st order ODE
    const size_t Np = particles.size();
    Vec_3D<FTYPE_t> vel;
    const FTYPE_t dDda = growth_change(a, cosmo); // dD / da
    
    #pragma omp parallel for private(vel)
    for (size_t i = 0; i < Np; i++)
    {
        vel.fill(0.);
        assign_from(vel_field, particles[i].position, vel);
        particles[i].velocity = vel*dDda;
    }
}

void kick_step_w_momentum	(	const Cosmo_Param &	cosmo,
		const double	a,
		const double	da,
		std::vector< Particle_v< double >> &	particles,
		const std::vector< Mesh > &	force_field
	)

Definition at line 48 of file integration.cpp.

References assign_from(), growth_allz::growth_factor, Cosmo_Param::Omega_L(), Cosmo_Param::Omega_m, and pow().

Referenced by App_Var_FP::upd_pos(), and App_Var_AA::upd_pos().

{
    // classical 2nd order ODE
    const size_t Np = particles.size();
    Vec_3D<FTYPE_t> force;
    const FTYPE_t D = growth_factor(a, cosmo);
    const FTYPE_t OL = cosmo.Omega_L()*pow(a,3);
    const FTYPE_t Om = cosmo.Omega_m;
    // -3/2a represents usual EOM, the rest are LCDM corrections
    const FTYPE_t f1 = 3/(2*a)*(Om+2*OL)/(Om+OL);
    const FTYPE_t f2 = 3/(2*a)*Om/(Om+OL)*D/a;
    
    #pragma omp parallel for private(force)
    for (size_t i = 0; i < Np; i++)
    {
        force.fill(0.);
        assign_from(force_field, particles[i].position, force);
        force = force*f2 - particles[i].velocity*f1;        
        particles[i].velocity += force*da;
    }
}

void kick_step_w_momentum_pm	(	const Cosmo_Param &	cosmo,
		const double	a,
		const double	da,
		std::vector< Particle_v< double >> &	particles,
		const std::vector< Mesh > &	force_field
	)

Definition at line 70 of file integration.cpp.

References assign_from(), growth_allz::growth_factor, Cosmo_Param::Omega_L(), Cosmo_Param::Omega_m, and pow().

Referenced by App_Var_PM::upd_pos().

{
    // classical 2nd order ODE
    const size_t Np = particles.size();
    Vec_3D<FTYPE_t> force;
    const FTYPE_t D = growth_factor(a, cosmo);
    const FTYPE_t OL = cosmo.Omega_L()*pow(a,3);
    const FTYPE_t Om = cosmo.Omega_m;
    // -3/2a represents usual EOM, the rest are LCDM corrections
    const FTYPE_t f1 = 3/(2*a)*(Om+2*OL)/(Om+OL);
    const FTYPE_t f2 = 3/(2*a)*Om/(Om+OL)/a;
    
    #pragma omp parallel for private(force)
    for (size_t i = 0; i < Np; i++)
    {
        force.fill(0.);
        assign_from(force_field, particles[i].position, force);
        force = force*f2 - particles[i].velocity*f1;        
        particles[i].velocity += force*da;
    }
}

void stream_kick_stream	(	const double	da,
		std::vector< Particle_v< double >> &	particles,
		std::function< void()>	kick_step,
		size_t	per
	)

Definition at line 24 of file integration.cpp.

References get_per(), and stream_step().

Referenced by App_Var_FF::upd_pos(), App_Var_FP::upd_pos(), App_Var_Chi::upd_pos(), App_Var_FP_mod::upd_pos(), App_Var_AA::upd_pos(), App_Var_PM::upd_pos(), and App_Var_Chi_FF::upd_pos().

{// general Leapfrog method: Stream-Kick-Stream & ensure periodicity
    stream_step(da/2, particles);
    kick_step();
    stream_step(da/2, particles);
    get_per(particles, per);
}

void stream_step	(	const double	da,
		std::vector< Particle_v< double >> &	particles
	)

Definition at line 14 of file integration.cpp.

Referenced by stream_kick_stream().

{
    const size_t Np = particles.size();
    #pragma omp parallel for
    for (size_t i = 0; i < Np; i++)
    {
        particles[i].position += particles[i].velocity*da;
    }
}