Pressure drop 45.6 Pa at 19.5 l/s · Pipe with a sudden expansion v2.ipt: internal flow, inlet 10 m/s, Air (20 °C)
LaminaroCFD · Laminaro add-in v0.41.0 · 2026-10-27 22:57:34Z UTC
Design: Pipe with a sudden expansion v2.ipt as of 2026-10-27 22:30 UTC · a copy is kept with this run (design.ipt)
Pressure drop (total)45.64 Pa
Loss coefficient K = Δp ÷ ½ρv² (v: mean inlet velocity)0.7582
Flow rate19.51 l/s
Good enough for engineering use. The pressure drop is steady within under ±0.1 % (last 200 iterations); mass balance 0.00 %. The remaining unsettledness is mostly next to the walls.
Measurements
| Measurement | Flow | Total p (flow-avg.) | Static p | Temperature | Force | Heat |
|---|
| Inlet | 19.51 l/s | 49.48 Pa | -10.72 ±0.0057 Pa | – | – | – |
| Outlet | 19.51 l/s | 4.015 ±0.021 Pa | 0 Pa | – | – | – |
| Before the step (Ø50) | 19.51 ±0.051 l/s | 42.01 ±0.52 Pa | -21.08 Pa | – | – | – |
| After the step (Ø100) | 19.51 ±0.027 l/s | 4.416 ±0.017 Pa | 0.2422 Pa | – | – | – |
± = how much the value moves between the solver's cell values and the same field smoothed over the cell corners (the mesh's resolution there).
Set-up
| Part | Pipe with a sudden expansion v2.ipt |
| Study | Example · Pipe with a sudden expansion |
| Where the fluid is | Modelled fluid body (flow inside the part) |
| Fluid | Air (20 °C) (ρ 1.204 kg/m³, ν 1.516e-05 m²/s) |
| Inlet | 10 m/s |
| Time behaviour | steady (mean values) |
| Turbulence | k-ω SST (automatic: Re ≈ 3.3·10⁴: turbulent) |
| Mesh level | Standard |
Pictures
What this result rests on
- Good enough for engineering use. The pressure drop is steady within under ±0.1 % (last 200 iterations); mass balance 0.00 %. The remaining unsettledness is mostly next to the walls.
- One mesh only: mesh independence was not checked.
- Steady RANS (k-ω SST): mean values. Vortex shedding, peaks and fluctuating loads are not resolved.
- Stopped at iteration 426: converged (the pressure drop steady within ±0.0 % over 200 iterations, residuals low).
Notes
- Mesh 501889 cells; values = mean of the last 10 % of 427 iterations.
- Δp = area-averaged pressure inlet → outlet; K = Δp_total / (½ρU²) with the inlet velocity; Re = 3.3e+04 (hydraulic diameter 0.05 m).
