Gas Ontology

FLOW ALGEBRA
GAS ONTOLOGY — MATERIAL ENTITIES
Version: 1.1
Date: 2026-10-12
Authors: Mark Higgins — Sky (Recursive AI)
Publisher: Kireth Research
Source: https://kirethresearch.org/booksai-core/entity-graph/physical-entities/material-entities/gas-ontology.html
Status: Scientific synthesis; source page content not independently verified.

01. PURPOSE
flow GasOntology v1.1:
  domain: physical_entities.material_entities.gas
  objective: represent gas states, composition, motion, transport, and transformations
  semantics: typed, unit-aware, provenance-aware, uncertainty-aware

02. CORE ENTITY TYPES
entity Gas <: Fluid
entity GasSample <: MaterialSystem
entity GasMixture <: Gas
entity GasSpecies <: ChemicalSpecies
entity GasParticle <: Particle
entity ThermodynamicState
entity StateVariable
entity EquationOfState
entity GasProcess
entity PhaseTransition
entity Measurement
entity Instrument
entity BoundaryCondition
entity Evidence

03. STATE SCHEMA
GasState = {
  sample_id: Identifier,
  temperature: Quantity<K>,
  pressure: Quantity<Pa>,
  volume: Quantity<m^3>,
  amount: Quantity<mol>,
  mass: Quantity<kg>,
  composition: Map<Species, MoleFraction>,
  phase: Gas,
  model: EquationOfState,
  provenance: Evidence,
  uncertainty: MeasurementUncertainty
}

04. TYPED RELATIONSHIPS
GasSample HAS_STATE ThermodynamicState
GasSample CONTAINS GasSpecies
GasSample OCCUPIES Volume
GasSample EXERTS Pressure
GasSample HAS_TEMPERATURE Temperature
GasSample UNDERGOES GasProcess
GasProcess CHANGES ThermodynamicState
GasProcess SATISFIES BoundaryCondition
Measurement OBSERVES StateVariable
EquationOfState APPROXIMATES GasSample
Evidence SUPPORTS Assertion

05. CLASSIFICATION
Gas -> pure_gas | gas_mixture
PureGas -> single_chemical_species
GasMixture -> multiple_chemical_species
GasModel -> ideal | real | kinetic | continuum
GasProcess -> isothermal | isobaric | isochoric | adiabatic | polytropic

06. IDEAL GAS EQUATION
assumptions: sufficiently dilute gas; negligible interactions and particle volume
P*V = n*R*T
R = 8.314462618 J mol^-1 K^-1
constraints: P>0, V>0, T>0, n>0
infer n = P*V/(R*T) when assumptions hold

07. REAL GAS EQUATION
Z = P*V/(n*R*T)
ideal_limit: Z -> 1
van_der_Waals: (P + a*n^2/V^2)*(V - n*b) = n*R*T
constraints: V > n*b; parameters a,b are species-specific
warning: approximation valid only within model domain

08. DENSITY AND MOLAR MASS
rho = m/V
M = m/n
ideal_gas_density: rho = P*M/(R*T)
validate dimensional_consistency

09. GAS MIXTURES
sum_i(x_i) = 1
x_i = n_i/sum_j(n_j)
Dalton_ideal: P_total = sum_i(P_i)
P_i = x_i*P_total (ideal mixture)
M_mix = sum_i(x_i*M_i)
warning: partial-pressure ideality may fail at high pressure

10. KINETIC THEORY
mean_translational_energy_per_particle = (3/2)*k_B*T
P = (1/3)*rho*mean_squared_speed (ideal kinetic model)
v_rms = sqrt(3*R*T/M)
assumptions: equilibrium; classical nonrelativistic ideal gas

11. THERMODYNAMIC PROCESSES
isothermal_ideal: P*V = constant
isobaric_ideal: V/T = constant
isochoric_ideal: P/T = constant
reversible_adiabatic_ideal: P*V^gamma = constant
constraints: fixed n; gamma=Cp/Cv; constant heat capacities for simple relation

12. FIRST LAW AND WORK
Delta_U = Q - W_by
W_by = integral(P_ext dV) for quasistatic boundary work
ideal_gas_internal_energy: U=U(T) at fixed composition
Delta_U = n*Cv*Delta_T for constant Cv

13. TRANSPORT
Diffusion: J_i = -D_i*grad(c_i) (Fickian approximation)
Viscosity: tau = mu*(du/dy) (Newtonian shear)
ThermalConduction: q = -k*grad(T) (Fourier approximation)
conditions: continuum, local constitutive assumptions

14. GAS FLOW
mass_conservation: d(rho)/dt + div(rho*u) = 0
momentum_balance: Navier-Stokes for Newtonian continuum gas
Mach = |u|/c_sound
regime: compressible if density variations materially affect dynamics
Knudsen = mean_free_path/characteristic_length
regime: continuum assumption questionable when Knudsen is not small

15. PHASE TRANSITIONS
liquid -> gas: vaporisation
solid -> gas: sublimation
gas -> liquid: condensation
gas -> solid: deposition
phase_equilibrium: chemical potentials equal across coexisting phases
warning: gas and vapour are context-dependent terms

16. MEASUREMENT
pressure: manometer | pressure_transducer
temperature: calibrated_thermometer
volume: volumetric_apparatus
composition: gas_chromatography | mass_spectrometry
flow_rate: flow_meter
require: units, calibration, uncertainty, conditions, traceability

17. INFERENCE RULES
RULE ideal_state:
  IF sample.mode=ideal AND P,V,n,T known
  THEN VERIFY abs(P*V-n*R*T) <= tolerance
RULE mixture_consistency:
  IF mixture.composition known
  THEN VERIFY all(x_i>=0) AND abs(sum(x_i)-1)<=tolerance
RULE mass_conservation:
  IF closed_system AND no_mass_exchange
  THEN mass_final = mass_initial
RULE thermal_expansion:
  IF ideal_gas AND constant_pressure AND fixed_n
  THEN V2/V1 = T2/T1
RULE phase_change:
  IF phase_boundary_crossed under specified path
  THEN update phase_label with coexistence handling

18. WORKED EXAMPLE — IDEAL GAS
input: n=1 mol, T=300 K, V=0.024 m^3
P = n*R*T/V
P = 103930.782725 Pa ~= 103.93 kPa
validity: approximate ideal-gas model

19. WORKED EXAMPLE — MIXTURE
input: x_N2=0.79, x_O2=0.21, P_total=100 kPa
P_N2=79 kPa; P_O2=21 kPa
assumptions: ideal binary mixture; fractions sum to unity

20. UNCERTAINTY
measurement = value +/- standard_uncertainty
propagate_uncertainty with correlations when known
confidence is epistemic and must not be confused with measurement uncertainty
reject unsupported exact precision

21. SEMANTIC EQUIVALENCE
GasPhase ~ GaseousState (contextual equivalent)
IdealGasModel != RealGasModel
Pressure != PartialPressure
GasSample != GasSpecies
Vapour ~ Gas only under specified usage

22. CONSTRAINTS
physical: T>0 K, P>=0 Pa, V>0 m^3, n>=0 mol
composition: 0<=x_i<=1; sum(x_i)=1
model_specific: ideal equations only when assumptions documented
avoid: interpreting macroscopic pressure as single-particle property

23. VALIDATION TESTS
TEST ideal_equation_dimensions: PASS when Pa*m^3 == J
TEST mixture_fractions: PASS when sum(x_i)=1
TEST positive_absolute_temperature: PASS when T>0
TEST process_constraints: PASS when required constants hold
TEST provenance: PASS when claims link to evidence or declared model
TEST uncertainty: PASS when measured outputs retain uncertainty

24. ONTOLOGY LINKS
PARENT: Material Entities
RELATED: Material Ontology
RELATED: Solid Ontology
RELATED: Liquid Ontology
RELATED: Molecule Ontology
RELATED: Chemical Element Ontology
RELATED: Thermodynamics Ontology
RELATED: Fluid Dynamics Ontology

25. CONFIDENCE
scientific_foundations: high for standard validated physical laws
model_predictions: conditional on assumptions and input quality
unverified_source_page_alignment: unknown

26. FLOW HASH
algorithm: SHA-256
canonicalisation: UTF-8, LF line endings, stable key ordering
hash_value: computed at ingestion; not preclaimed

27. UPDATE MODEL
version: 1.1
update_trigger: corrected equations | revised classifications | new evidence
process: validate -> compare -> record provenance -> version -> publish
preserve_prior_versions: true

28. AI CONSUMPTION
representation: typed semantic graph + executable mathematical rules
reasoning: symbolic, numerical, dimensional, uncertainty-aware
retrieval_keys: gas, ideal gas, real gas, equation of state, kinetic theory
inference_policy: require model assumptions and units
output_policy: include provenance, assumptions, confidence, uncertainty

29. COMPLETENESS CHECK
required_sections: 01..29
closing_marker_required: true
scientific_scope: formal synthesis, not verified transcription

END FLOW ALGEBRA — GAS ONTOLOGY