include/pops/physics/bricks/source.hpp Source File

adc_cpp 0.3.0 Model-free C++23 core for coupled hyperbolic-elliptic systems on adaptive (AMR) meshes, with MPI and GPU (Kokkos) backends

• include
• pops
• physics
• bricks

source.hpp

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1#pragma once

2

3#include <pops/core/model/physical_model.hpp> // aux_comps<>: propagates the aux channel of a composite source

4#include <pops/core/state/state.hpp>

5#include <pops/core/foundation/types.hpp>

6

14

15namespace pops {

16

17// OPTIONAL CONTRACT frequency(U, aux) -> Real (audit 2026-06, step_cfl work): a source brick

18// may declare its local FREQUENCY mu [1/s] (relaxation/collision/reaction rate). When the brick

19// exposes it, CompositeModel forwards it (source_frequency) and System::step_cfl enforces the

20// bound dt <= cfl * substeps / (stride * max_cells(mu)) -- the meeting's "second CFL" (source),

21// distinct from the transport CFL (no h: a source is bounded in 1/time). A brick WITHOUT

22// frequency (all of those in this file today) does not constrain the step (historical). Must be

23// POPS_HD (evaluated inside a reduction kernel).

24

27struct NoSource {

28 template <class State>

29 POPS_HD State apply(const State&, const Aux&) const {

30 return State{};

31 }

32};

33

47struct PotentialForce {

48 Real qom = 1; // q/m (sign included)

49 int c_rho = 0, c_mx = 1, c_my = 2, c_E = 3; // defaults = canonical fluid layout (bit-identical)

50 template <class State>

51 POPS_HD State apply(const State& u, const Aux& a) const {

52 const Real Ex = -a.grad_x, Ey = -a.grad_y;

53 State s{};

54 s[c_mx] = qom * u[c_rho] * Ex;

55 s[c_my] = qom * u[c_rho] * Ey;

56 if constexpr (State::size() == 4)

57 s[c_E] = qom * (u[c_mx] * Ex + u[c_my] * Ey);

58 return s;

59 }

60};

61

73struct GravityForce {

74 int c_rho = 0, c_mx = 1, c_my = 2, c_E = 3; // defaults = canonical fluid layout (bit-identical)

75 template <class State>

76 POPS_HD State apply(const State& u, const Aux& a) const {

77 const Real gx = -a.grad_x, gy = -a.grad_y;

78 State s{};

79 s[c_mx] = u[c_rho] * gx;

80 s[c_my] = u[c_rho] * gy;

81 if constexpr (State::size() == 4)

82 s[c_E] = u[c_mx] * gx + u[c_my] * gy;

83 return s;

84 }

85};

86

104struct MagneticLorentzForce {

105 Real qom = 1; // q/m (sign included)

106 static constexpr int n_aux = 4; // reads B_z (extra aux channel, canonical index 3)

107 // ROLE-AWARE (audit section 5): only the MOMENTUM components are read/written (the magnetic

108 // force touches neither density nor energy -- zero work). c_mx/c_my are members, defaults =

109 // canonical layout (m_x=1, m_y=2), resolved by model_factory via the transport roles. Canonical

110 // == defaults -> bit-identical. POD integers -> device-clean.

111 int c_mx = 1, c_my = 2;

112 template <class State>

113 POPS_HD State apply(const State& u, const Aux& a) const {

114 static_assert(

115 State::size() >= 3,

116 "MagneticLorentzForce : requires a fluid transport >= 3 variables (momentum on 2 axes)");

117 const Real c = qom * a.B_z;

118 State s{};

119 s[c_mx] = c * u[c_my]; // +qom B_z m_(y/theta)

120 s[c_my] = -c * u[c_mx]; // -qom B_z m_(x/r)

121 // energy stays 0: v x B is perpendicular to v, zero work.

122 return s;

123 }

124};

125

135template <class A, class B>

136struct CompositeSource {

137 A a{};

138 B b{};

139 static constexpr int n_aux = aux_comps<A>() > aux_comps<B>() ? aux_comps<A>() : aux_comps<B>();

140 template <class State>

141 POPS_HD State apply(const State& u, const Aux& ax) const {

142 return a.apply(u, ax) + b.apply(u, ax);

143 }

144};

145

146} // namespace pops

pops

Definition amr_hierarchy.hpp:29

pops::Real

double Real

Definition types.hpp:30

pops::aux_comps

POPS_HD constexpr int aux_comps()

Width of the aux channel a model CONSUMES.

Definition physical_model.hpp:67

physical_model.hpp

C++20 concepts defining the contract of the physics layer.

state.hpp

Pointwise types of the physics layer: StateVec<N> (conserved state) and Aux (auxiliary fields from th...

pops::Aux

POINTWISE auxiliary fields shared with the physics: single coupling channel.

Definition state.hpp:123

pops::Aux::grad_y

Real grad_y

Definition state.hpp:126

pops::Aux::grad_x

Real grad_x

Definition state.hpp:125

pops::CompositeSource

SUM of two source bricks: S(U, aux) = A.apply(U, aux) + B.apply(U, aux).

Definition source.hpp:136

pops::CompositeSource::apply

POPS_HD State apply(const State &u, const Aux &ax) const

Definition source.hpp:141

pops::CompositeSource::a

A a

Definition source.hpp:137

pops::CompositeSource::n_aux

static constexpr int n_aux

Definition source.hpp:139

pops::CompositeSource::b

B b

Definition source.hpp:138

pops::GravityForce

Gravitational force rho g (+ work if 4 variables).

Definition source.hpp:73

pops::GravityForce::c_my

int c_my

Definition source.hpp:74

pops::GravityForce::c_E

int c_E

Definition source.hpp:74

pops::GravityForce::apply

POPS_HD State apply(const State &u, const Aux &a) const

Definition source.hpp:76

pops::GravityForce::c_rho

int c_rho

Definition source.hpp:74

pops::GravityForce::c_mx

int c_mx

Definition source.hpp:74

pops::MagneticLorentzForce

MAGNETIC Lorentz force q (v x B) on momentum, field B = B_z z_hat out of plane.

Definition source.hpp:104

pops::MagneticLorentzForce::apply

POPS_HD State apply(const State &u, const Aux &a) const

Definition source.hpp:113

pops::MagneticLorentzForce::c_my

int c_my

Definition source.hpp:111

pops::MagneticLorentzForce::qom

Real qom

Definition source.hpp:105

pops::MagneticLorentzForce::c_mx

int c_mx

Definition source.hpp:111

pops::MagneticLorentzForce::n_aux

static constexpr int n_aux

Definition source.hpp:106

pops::NoSource

No source: S(U, aux) = 0.

Definition source.hpp:27

pops::NoSource::apply

POPS_HD State apply(const State &, const Aux &) const

Definition source.hpp:29

pops::PotentialForce

Electrostatic potential force (q/m) rho E on momentum (+ work on energy if 4 variables).

Definition source.hpp:47

pops::PotentialForce::c_E

int c_E

Definition source.hpp:49

pops::PotentialForce::c_rho

int c_rho

Definition source.hpp:49

pops::PotentialForce::c_mx

int c_mx

Definition source.hpp:49

pops::PotentialForce::c_my

int c_my

Definition source.hpp:49

pops::PotentialForce::qom

Real qom

Definition source.hpp:48

pops::PotentialForce::apply

POPS_HD State apply(const State &u, const Aux &a) const

Definition source.hpp:51

types.hpp

Base scalar types and the POPS_HD macro (host+device portability).

POPS_HD

#define POPS_HD

Definition types.hpp:25

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