On the dynamics of NaCl‐H2O fluid convection in the Earth's crust

摘要: [1] Numerical simulations of transient porous media thermohaline convection including phase separation into a high-density, high-salinity brine and low-density, low-salinity vapor at pressures temperatures well above the critical point pure H2O are presented. Using novel finite element–finite volume (FEFV) solution technique new equation state for binary NaCl-H2O system, fluid in an open top square box 4 × km is studied geologically realistic pressure p, temperature T, salinity X conditions. In simulations, basal varied systematically from 200 to 600°C 3.2 40 or 60 wt % NaCl, permeabilities 10−15 10−14 m2 hydrostatic Resulting flow patterns diffusive, steady convective, oscillatory. Single-phase occurs below 400°C. Between 400 450°C, can occur during buoyant rise heat salt if permeability high low. Above boundary coexisting with phase. this case, dominated by transport vapor. Convection sets almost instantaneously these 570°C, nearly coexists solid boundary. driven exclusively applied gradient. Since properties change highly nonlinear functions X, parameters such as Rayleigh number buoyancy ratio, which classically used quantify different regimes convection, not meaningful context. This implies that parametric studies make use Boussinesq approximation assume incompressibility representative geologic environments. We concept local fluxibility parameter provide better insight onset evolution convective systems.