CFD Solvers

rhoPimpleFoam is a transient solver for compressible, density-dependent flows using the PIMPLE algorithm. It solves the energy equation and computes density from thermophysical properties. SIMD Agent selects it for unsteady compressible problems including pressure waves, acoustics, and cryogenic flows.

When the agent selects this solver

• Compressible flow (Mach > 0.3, large pressure differentials)
• Transient solution needed
• Gravity is not the dominant driving force
• Cryogenic single-phase liquids in transient simulations

Typical applications include shock-tube problems, transient high-speed flows with heat transfer, pressure wave propagation, acoustic simulations, and cryogenic fluid handling. For fluids not natively supported by OpenFOAM, the agent generates polynomial-fitted properties automatically. See Custom Fluid Properties.

Required files

Pressure field

Absolute pressure in Pascals [1 -1 -2 0 0 0 0]. Temperature in Kelvin. Same as rhoSimpleFoam.

Time control

endTime and deltaT are in physical seconds, not iteration counts.

application  rhoPimpleFoam;
startTime    0;
endTime      0.5;     // physical seconds
deltaT       1e-5;    // physical time step

PIMPLE settings

Requires outer correctors for pressure-density-energy coupling. The rho solver entry is mandatory in fvSolution/solvers even though no 0/rho file exists.

PIMPLE
{
    nOuterCorrectors    2;
    nCorrectors         1;
    nNonOrthogonalCorrectors 1;
}

solvers
{
    rho
    {
        solver  diagonal;
    }
    // ... other solvers
}

Energy equation

Solves for he (sensible enthalpy or internal energy). The energy variable must be consistent across all configuration files. Generate 0/alphat with compressible::alphatWallFunction when both turbulence and energy are active.

GAMG smoother

The GAMG smoother must be set to GaussSeidel.

Files never generated

• 0/rho, density is computed at runtime
• 0/h, 0/e, enthalpy via he
• constant/g, no gravity