Examples gallery
OpenFLUME ships with fourteen example models, found in the toolbar's Examples ▾ menu in the four groups used below. The descriptions come from each example's canvas notes and the model definitions in src/ui/examples.ts; user manual §7 has a longer write-up of each.
Each Open in browser link loads a fresh copy of the example into the app at https://openflume.github.io/OpenFLUME/. Loading an example replaces the model you have open, so Save your work first. Nothing is uploaded; the model runs in your browser when you click Run.
Every example is an ordinary model. To start your own, open the nearest example and edit it.
Verify-by-inspection
Sanity: orifice hand-calc
Steady · incompressible water
Water flows from a 200 kPa boundary to a 100 kPa boundary through a single orifice (area 1×10⁻⁴ m², Cd = 0.6). The canvas note gives the hand answer, Cd A sqrt(2 ρ ΔP) ≈ 0.849 kg/s, and the solved flow should match it within 0.5 %. It is the smallest model that exercises the whole chain: loading, validation, Newton solve, and reported result.
Demonstrates: a first run after installing or updating, and checking a solver result against a closed form.
Applications
Three-pipe junction
Steady · incompressible water
Water enters at 300 kPa through one pipe and splits into two pipes that discharge to outlets at 200 kPa and 150 kPa, so the split is uneven. The canvas note asks you to check that the two outlet flows sum to the inlet flow. The two downstream pipes take their roughness from the first pipe through a formula binding.
Demonstrates: Darcy–Weisbach pipes with the Swamee–Jain friction factor, junction continuity, and how a diameter change moves the split. Used in Lab 1.
Tank blowdown
Transient · ideal-gas air
A 0.1 m³ tank of air starts at 500 kPa and 300 K and vents through an orifice to 101 kPa outside air. Over the 5 s run (fixed 0.01 s step), tank pressure falls and the gas cools well below 300 K, because the tank stores internal energy while the outflow carries enthalpy.
Demonstrates: transient storage in a tank node, a choked gas orifice, and adiabatic expansion cooling. See the tank blowdown tutorial and Lab 2.
Water distribution network
Steady · incompressible water
A pump pushes water through a main header into three parallel legs, each with a valve that can be part open (positions 0.5, 0.8, and 1.0). One leg rises 3 m and one falls 3 m, and the two return lines discharge at different elevations and pressures. Change the valve settings to move flow between paths. Several pipes and valves are formula-bound to Leg 1, so editing it updates the others.
Demonstrates: a pump operating point on a piecewise-linear curve, elevation sign conventions, valve throttling, and pressure along a flow path. Used in Lab 1.
Heated pipe with radiating wall (conjugate HT)
Steady · incompressible water · conjugate heat transfer
Water flows through two pipe sections and an outlet orifice. Each section is wrapped by a wall node heated at 5000 W. Heat moves into the water by convection, along the wall by conduction, and out to 300 K surroundings by radiation. The convection areas are formulas tied to the pipes' surface area.
Demonstrates: solid and ambient nodes with all three conductor kinds in the smallest model that uses them together, and closing a solid–fluid energy balance. Used in Lab 3.
Spacecraft radiator panel (ammonia loop heat pipe)
Steady · real-fluid ammonia · two-phase · conjugate heat transfer
A wicked evaporator boils ammonia with 350 W of avionics heat. The vapor travels 1.5 m to a flat radiator panel and condenses, and the liquid returns to the compensation chamber. There is no mechanical pump: the wick is modeled as a flow source that passes the liquid the heat can boil (0.32 g/s), and the loop needs only about 68 Pa. The canvas note gives the expected results: vapor quality 0.98 in the vapor line, a condenser that stays at about 306 K, and about 6 K of subcooling in the last strip. The temperature drops occur in the hardware, not the fluid.
Demonstrates: real-fluid two-phase flow, radiation to space, a two-dimensional conduction network in a face sheet, and the 3-D view (the panel lies in the x–y plane).
LOX/RP-1 thruster (combustor)
Steady · reacting junction · compressible nozzle · conjugate heat transfer
LOX and RP-1 injectors discharge into a reacting junction whose hot-gas state comes from a NASA CEA chemical-equilibrium lookup with an enthalpy efficiency of 0.9409. The gas then expands through a choked converging–diverging nozzle with Momentum flux and Kinetic energy on. The RP-1 cools the nozzle through a regenerative jacket with a three-layer copper wall at every station. The exhaust boundary is set to the matched-expansion pressure: a boundary node imposes a static pressure, and any other value would back-propagate into the last station.
Demonstrates: CEA-coupled combustion, quasi-1-D choked nozzle flow, mixed equations of state in one model, and regenerative cooling. Details are in combustion.md and the combustion validation report.
LOX/RP-1 thruster (transient startup)
Transient · reacting junction · compressible nozzle
The same thruster, run as a startup. Both propellant tanks ramp from 100 psi to 1000 psi over the first second and then hold for a second. The chamber's energy closure is quasi-steady, but its mass balance has a real storage term, so chamber pressure follows the feed ramp with a lag of about 0.3 ms. The exhaust boundary is fixed at 30 kPa instead of sea level, which keeps the nozzle profile monotone across the whole ramp.
Demonstrates: a transient reacting junction, pressure schedules on boundary nodes, and node volumes on a discretized nozzle.
Capillary circuit (stop + trigger valve)
Transient · incompressible water · capillary channels
A water sample wicks from the inlet into two microchannels with no pump. Short path A ends in a stop valve at the junction and waits there. When the longer delay path B arrives, its liquid meets A's meniscus and releases the valve (a trigger valve). The stream then wicks into a capillary pump while air leaves through the vent. Plot each channel's Liquid fill in Results to see the sequence.
Demonstrates: capillary-driven filling, stop and trigger valves, and event timing in microfluidic circuits. See the microfluidics validation report.
Benchmarks
Water-water counterflow heat exchanger
Steady · incompressible water · conjugate heat transfer
Reproduces Example 5 of NASA's GFSSP manual. Hot water flows left to right and cold water right to left, exchanging heat through a wall split into 12 segments. After Run, the outlet temperatures should be within 0.44 K (hot) and 0.19 K (cold) of the published values.
Demonstrates: a code-to-code conjugate heat-transfer benchmark and the effect of segment count on heat-exchanger accuracy. Case 5 of the thermal network validation report studies the segmentation error.
Entrapped-air line
Transient · incompressible water with a trapped-gas cushion
Reproduces GFSSP Figure 10 (Lee and Martin). Water fills a long pipe with trapped air at the far end. Each pipe segment has fluid inertia, so the flow cannot change instantly. The valve opens at about 0.15 s, and the pressure at node 12 then rises and falls as the air cushion compresses and rebounds.
Demonstrates: lumped fluid inertia and the polytropic gas cushion working together. This is bulk surge; OpenFLUME does not model acoustic wave propagation. See the fluid transient validation report.
Cryogenic line cooldown
Transient · real-fluid hydrogen · two-phase · conjugate heat transfer
The SINDA/FLUINT validation case from NBS Report 9264, Figure 2. Saturated liquid hydrogen enters a warm copper transfer line and chills the wall station by station. Run it and watch the quench front move down the line.
Demonstrates: real-fluid two-phase (HEM) flow, film-boiling heat transfer, temperature-dependent copper properties, and why axial discretization matters for a moving front. See the cryogenic chilldown guide.
Extensibility
Extension: Cryo tank vent control (transient)
Transient · real-fluid nitrogen · logic and controllers
A cold nitrogen tank receives 400 W of heat. The vent opens when tank pressure gets too high and closes once it has dropped far enough; the band is 5 psi wide around about 3.2 bar. Logic rules set a ventOpen register, a controller drives the valve fully open or closed, and other registers count vent events and track the peak pressure.
Demonstrates: registers, declarative logic rules, hysteresis, and a register-following controller, with no component code. The contract is in usercode.md.
LH2 tank no-vent fill
Transient · real-fluid parahydrogen · conjugate heat transfer · logic and controllers
Reproduces SINDA/FLUINT Sample Problem F (TVS): a no-vent fill of a half-full, saturated liquid-hydrogen tank from a 60 psia source. FLUINT's twinned tanks and moveable ties are emulated with registers, logic rules, and controllers, using CoolProp properties read back from the solver. At 15 minutes the note reports fill 73.4 % (deck 73.9 %) and pressure 59.63 psia (59.72). The vapor-cooled shield and internal heat exchanger are carried as thermal mass only, not as flow paths. Read the note and the module header of src/ui/lh2StorageTank.ts before using this example as a template.
Demonstrates: how far registers, logic, and controllers can stretch to emulate features the schema lacks, and how to document what is emulated versus matched.
Limits
The examples stay inside what OpenFLUME models. It has no shock capture, no acoustic or water-hammer wave propagation (fluid inertia is lumped per branch), cavitation only at venturi closure, turbomachinery as a pump curve only, no general junction mixing outside CEA reacting junctions, and homogeneous (HEM) two-phase flow only. Embedded user code is trusted, not sandboxed. A steady closed ideal-gas loop needs a pressure anchor. OpenFLUME is alpha software (0.3.1). The full list is in user manual §1.7.