Unsaturated flow, constitutive curves and coupling
Research context
research method · conditional · As of 2026-10-10
Richards flow conserves water in a variably saturated porous medium while Darcy flux uses saturation-dependent permeability.
Key knowledge
Richards flow conserves water in a variably saturated porous medium while Darcy flux uses saturation-dependent permeability. Retention and relative-permeability curves are constitutive inputs; coupling reactive changes in porosity to flow requires consistent accumulation and flux updates.
Values and equations
∂(φ s η)/∂t + div(η q) = Qw
- φ
- Porosity 1
- s
- Water saturation 1
- η
- Molar water density kmol m^-3
- q
- Darcy volume flux m s^-1
- Qw
- Molar source density kmol m^-3 s^-1
Conditions and scope
- The specified PFLOTRAN Richards mode is single-phase, isothermal; multiphase or thermal effects need additional equations.
- Test time/mesh refinement, boundary fluxes and mass residuals; implicit solves still have splitting and truncation error.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
PFLOTRAN Richards mode: Governing mass-conservation equation, Darcy flux and constitutive functions (selected source body inspected). PFLOTRAN method of solution: Finite-volume accumulation, implicit solves and operator splitting (selected source body inspected).
2026-10-10 · Bounded source check of the recorded statement and conditions. This does not certify a unique physical model, reproduce the cited study or replace independent branch review.
Entry details
Permanent link to this entry ↗- Record identity
- research-earth-unsaturated-conservation
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference