include/pops/validation/physics/two_fluid_isothermal.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

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two_fluid_isothermal.hpp

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1#pragma once

2

12

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

14

15#include <cmath>

16

17namespace pops::validation {

18

43struct TwoFluidLinear {

44 Real omega_pe = 1, omega_pi = 0;

45 Real cse2k2 = 0, csi2k2 = 0;

46

54 POPS_HD void explicit_step(Real& Ae, Real& Ai, Real& Be, Real& Bi, Real dt) const {

55 Be += dt * (-cse2k2 * Ae);

56 Bi += dt * (-csi2k2 * Ai);

57 }

58

69 POPS_HD void implicit_solve(Real& Ae, Real& Ai, Real& Be, Real& Bi, Real dt) const {

70 const Real wpe2 = omega_pe * omega_pe, wpi2 = omega_pi * omega_pi, d2 = dt * dt;

71 const Real re = Ae + dt * Be, ri = Ai + dt * Bi; // known right-hand sides

72 const Real a = 1 + d2 * wpe2, b = -d2 * wpe2; // I - dt^2 M_s

73 const Real c = -d2 * wpi2, dd = 1 + d2 * wpi2;

74 const Real det = a * dd - b * c;

75 Ae = (dd * re - b * ri) / det;

76 Ai = (-c * re + a * ri) / det;

77 Be = Be + dt * (-wpe2 * Ae + wpe2 * Ai); // B* + dt M_s A^{n+1}

78 Bi = Bi + dt * (wpi2 * Ae - wpi2 * Ai);

79 }

80

87 void dispersion(Real& w_fast, Real& w_slow) const {

88 const Real wpe2 = omega_pe * omega_pe, wpi2 = omega_pi * omega_pi;

89 const Real S = cse2k2 + csi2k2 + wpe2 + wpi2; // = w_fast^2 + w_slow^2

90 const Real P = cse2k2 * csi2k2 + wpe2 * csi2k2 + wpi2 * cse2k2; // = product

91 const Real disc = std::sqrt(std::fmax(S * S - 4 * P, Real(0)));

92 w_fast = std::sqrt(Real(0.5) * (S + disc));

93 w_slow = std::sqrt(std::fmax(Real(0.5) * (S - disc), Real(0)));

94 }

95};

96

97} // namespace pops::validation

pops::validation

Definition advection_diffusion.hpp:22

pops::Real

double Real

Definition types.hpp:30

pops::validation::TwoFluidLinear

Isothermal two-fluid electrostatic, linear mode (single Fourier k).

Definition two_fluid_isothermal.hpp:43

pops::validation::TwoFluidLinear::omega_pe

Real omega_pe

Definition two_fluid_isothermal.hpp:44

pops::validation::TwoFluidLinear::dispersion

void dispersion(Real &w_fast, Real &w_slow) const

Roots of the dispersion relation, w_fast (Langmuir) >= w_slow (ion-acoustic) >= 0.

Definition two_fluid_isothermal.hpp:87

pops::validation::TwoFluidLinear::csi2k2

Real csi2k2

c_se^2 k^2, c_si^2 k^2 (acoustic terms)

Definition two_fluid_isothermal.hpp:45

pops::validation::TwoFluidLinear::omega_pi

Real omega_pi

plasma frequencies electron / ion

Definition two_fluid_isothermal.hpp:44

pops::validation::TwoFluidLinear::explicit_step

POPS_HD void explicit_step(Real &Ae, Real &Ai, Real &Be, Real &Bi, Real dt) const

Explicit step (slow acoustic term) in place: B_s += dt (-c_s^2 k^2 A_s).

Definition two_fluid_isothermal.hpp:54

pops::validation::TwoFluidLinear::cse2k2

Real cse2k2

Definition two_fluid_isothermal.hpp:45

pops::validation::TwoFluidLinear::implicit_solve

POPS_HD void implicit_solve(Real &Ae, Real &Ai, Real &Be, Real &Bi, Real dt) const

Implicit step (stiff plasma term) in place: (A,B) <- (A*,B*) + dt S.

Definition two_fluid_isothermal.hpp:69

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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