IsothermalFlux Struct ReferenceΒΆ

adc_cpp: pops::IsothermalFlux Struct Reference
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
Public Types | Public Member Functions | Static Public Member Functions | Public Attributes | Static Public Attributes | List of all members
pops::IsothermalFlux Struct Reference

ISOTHERMAL Euler flux (p = cs2 rho), 3 variables (rho, rho u, rho v). More...

#include <hyperbolic.hpp>

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Public Types

using State = StateVec< 3 >
 conservative variables (rho, rho u, rho v)
 
using Prim = StateVec< 3 >
 primitive variables (rho, u, v)
 

Public Member Functions

POPS_HD Real velocity_rho (Real rho) const
 rho clamped from below by vacuum_floor for the velocity division ONLY.
 
POPS_HD StateVec< 3 > flux (const StateVec< 3 > &u, const Aux &, int dir) const
 
POPS_HD Prim to_primitive (const StateVec< 3 > &u) const
 Conservative -> primitive: (rho, rho u, rho v) -> (rho, u, v).
 
POPS_HD StateVec< 3 > to_conservative (const Prim &p) const
 Primitive -> conservative: (rho, u, v) -> (rho, rho u, rho v).
 
POPS_HD Real max_wave_speed (const StateVec< 3 > &u, const Aux &, int dir) const
 
POPS_HD StateVec< 3 > eigenvalues (const StateVec< 3 > &u, const Aux &, int dir) const
 Full spectrum: (v_dir - c, v_dir, v_dir + c), c = sqrt(cs2).
 
POPS_HD void wave_speeds (const StateVec< 3 > &u, const Aux &, int dir, Real &smin, Real &smax) const
 Signed speeds (HLL/HLLC): v_dir -+ c_s.
 

Static Public Member Functions

static VariableSet conservative_vars ()
 
static VariableSet primitive_vars ()
 

Public Attributes

Real cs2 = 1
 
Real vacuum_floor = 0
 Quasi-vacuum density floor (ADC-77).
 

Static Public Attributes

static constexpr int n_vars = 3
 

Detailed Description

ISOTHERMAL Euler flux (p = cs2 rho), 3 variables (rho, rho u, rho v).

3-variable HYPERBOLIC brick (density + momenta). Satisfies HyperbolicPhysicalModel. Isothermal closure law: p = cs2 * rho (no energy equation). CONTRACT: purely pointwise functions, device-callable (POPS_HD). No MultiFab, no allocation, no global access. Invariant: cs2 > 0 so that the wave speed sqrt(cs2) is real.

Member Typedef Documentation

◆ Prim

using pops::IsothermalFlux::Prim = StateVec<3>

primitive variables (rho, u, v)

◆ State

using pops::IsothermalFlux::State = StateVec<3>

conservative variables (rho, rho u, rho v)

Member Function Documentation

◆ conservative_vars()

static VariableSet pops::IsothermalFlux::conservative_vars ( )
inlinestatic

◆ eigenvalues()

POPS_HD StateVec< 3 > pops::IsothermalFlux::eigenvalues ( const StateVec< 3 > &  u,
const Aux &  ,
int  dir 
) const
inline

Full spectrum: (v_dir - c, v_dir, v_dir + c), c = sqrt(cs2).

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◆ flux()

POPS_HD StateVec< 3 > pops::IsothermalFlux::flux ( const StateVec< 3 > &  u,
const Aux &  ,
int  dir 
) const
inline
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◆ max_wave_speed()

POPS_HD Real pops::IsothermalFlux::max_wave_speed ( const StateVec< 3 > &  u,
const Aux &  ,
int  dir 
) const
inline
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◆ primitive_vars()

static VariableSet pops::IsothermalFlux::primitive_vars ( )
inlinestatic

◆ to_conservative()

POPS_HD StateVec< 3 > pops::IsothermalFlux::to_conservative ( const Prim &  p) const
inline

Primitive -> conservative: (rho, u, v) -> (rho, rho u, rho v).

◆ to_primitive()

POPS_HD Prim pops::IsothermalFlux::to_primitive ( const StateVec< 3 > &  u) const
inline

Conservative -> primitive: (rho, rho u, rho v) -> (rho, u, v).

The velocity uses the quasi-vacuum floored density (velocity_rho); rho itself (p[0]) stays the raw conserved value.

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◆ velocity_rho()

POPS_HD Real pops::IsothermalFlux::velocity_rho ( Real  rho) const
inline

rho clamped from below by vacuum_floor for the velocity division ONLY.

Manual max (device-safe, no std:: in the kernel path). floor <= 0 -> returns rho unchanged (bit-identical).

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◆ wave_speeds()

POPS_HD void pops::IsothermalFlux::wave_speeds ( const StateVec< 3 > &  u,
const Aux &  ,
int  dir,
Real &  smin,
Real &  smax 
) const
inline

Signed speeds (HLL/HLLC): v_dir -+ c_s.

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Member Data Documentation

◆ cs2

Real pops::IsothermalFlux::cs2 = 1

◆ n_vars

constexpr int pops::IsothermalFlux::n_vars = 3
staticconstexpr

◆ vacuum_floor

Real pops::IsothermalFlux::vacuum_floor = 0

Quasi-vacuum density floor (ADC-77).

When > 0, the velocity is computed as u = m / max(rho, vacuum_floor) so it stays bounded where the rollup evacuates the background (rho -> ~0); this bounds BOTH the CFL wave speed and the advective flux in one place (max_wave_speed and flux both divide by rho here). Mass and momentum are NOT modified – only the velocity ESTIMATE is bounded, so the conservative state is untouched (unlike a cell density clamp). <= 0: inactive, and the raw 1/rho path is taken verbatim (bit-identical, including for rho <= 0).

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