Gas Dynamics Calculator computes the classical relations of compressible flow — shock waves, expansion fans, flow in ducts with friction or heat addition, and nozzles — and exports the working, not just the answer.
| Module | What it is for |
|---|---|
| Isentropic flow | A Mach number fixes every ratio at a point. Two thermodynamic properties fix the absolute values. |
| Normal shock | One number, M₁, fixes everything across the shock. It is the first result that shows Mach number, not velocity, governs compressible flow. |
| Oblique shock | Every ratio is the normal shock relation evaluated at Mn₁ = M₁ sin(β). The module adds only geometry: which wave angle goes with which deflection. |
| Prandtl-Meyer expansion | A continuous succession of Mach waves, each with Δs = 0, so the whole fan is isentropic -- the sharpest possible contrast with a shock. |
| Rayleigh flow (heat addition) | Heat acts directly on the total temperature and always drives the Mach number towards 1. Enough of it chokes the duct. |
| Fanno flow (friction) | Adiabatic, so total temperature is constant and duct length is the driver. Like heat addition it drives the Mach number towards 1, and a long enough duct chokes. |
| Nozzle at a back pressure | The area ratio fixes only two operating points; the back pressure decides everything between and outside them, including where a shock stands inside. |
59 displayed relations in all. Each solves in both directions and shows the formula it used. Processes can be chained into flow paths, which report what was conserved across the whole sequence and what was lost.
Every relation is exact for a calorically perfect gas: γ and R constant. That is the assumption classical compressible-flow theory is built on, and it is the assumption this software makes everywhere. The application shows a warning when a result leaves the range where it holds.
There is no variable-specific-heat model, no high-temperature chemistry and no CFD. It is not offered for flight safety, for certification, or for critical engineering decisions taken without independent verification.
Write to softwareone.support@gmail.com. Say which module, what you entered and what you expected; if a number looks wrong, the exported worked solution contains everything needed to reproduce it, and pasting one is the fastest way to an answer.
Reports that a result is wrong are taken seriously and checked against the reference sources rather than argued with.
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