Study quality improvement suggestions

What to do next

Check the mesh: one run on a coarser mesh shows how much the cell size moves the result. check_mesh
2.5× fewer cells than this run, about 9 min; this run stays as it is. Then optionally a finer one for the full check (Verify ×3).
Make the cells next to the walls smaller (a finer mesh level). Run on the Fine mesh
y⁺ is about 1 285 on average: the first cell is too far from the wall for the wall model.

Convergence

●Precision ?PrecisionGood enough for engineering use. The drag (Cd) is steady within ±0.1 % (last 200 iterations). The remaining unsettledness is at the part itself: its forces may still change a little.good enough for engineering use
●StoppedStopped at iteration 302: converged (Cd steady within ±0.1 % over 200 iterations, residuals low).
●Drag (Cd) ?The ± on a resultHow much it moved over the last 200 iterations. ≤ ±1 %: good enough for engineering use · ±1–3 %: trends · above ±3 %: not settled yet.How much it moved over the last 200 iterations. ≤ ±1 %: good enough for engineering use · ±1–3 %: trends and comparisons · above ±3 %: not settled yet.±0.14 %
●Where it is still settling ?Where it is still settlingThe part of the flow that still changes between iterations; the 3D view colours it (Colour → Where still settling).the 3D view colours it: Colour → Where still settlingThe remaining unsettledness is at the part itself: its forces may still change a little.
●Residuals at the end ?ResidualsHow much the solver's equations are still out of balance, scaled. Low (below 10⁻³) or no longer falling, with steady key results, means the run is done. A hint; the ± on the key results is the measure that counts.Residuals measure how far the solver's equations are from being exactly satisfied in each cell; they shrink as the solution settles. Here they levelled off below the usual 10⁻⁴, so the flow field has settled. The key result moved by ±0.1 % over the last 200 iterations, so it is settled.pressure 1.1e-05 · velocity 1.1e-05
1e-61e-51e-41e-31e-21e-11e00.3650.364iterationpUCd (right axis)

Mesh

●Cells ?CellsThe number of cells the flow was computed on. More cells: finer detail and less mesh error, but a longer run. Draft is for set-up checks and trends, Standard for numbers you report, Fine to confirm them.380 900
●Mesh level ?Mesh levelDraft and quick look give trends; Standard is for numbers you report; Fine confirms them.Standard
●Max non-orthogonality ?Non-orthogonalityHow far the line between two cells' centres leans away from the face between them (0° = square on). Below 65°: good. 65–75°: fair, the solver corrects for it. Above 75°: poor: less accurate gradients, slower to settle, sometimes a blow-up. If poor: a finer mesh where it happens (sharp edges, thin gaps), or fewer wall layers there.below 65° good, above 75° poor (less accurate, slower to settle)54°
●Max skewness ?SkewnessHow far the face between two cells sits from the midpoint of the line between their centres, relative to the cell size. Below 4: good. 4–8: fair. Above 8: poor: values on the faces are interpolated wrongly. If poor: a finer mesh near curved walls and small features, or smooth tiny details away in Inventor.2.269
●Mesh checksall passed
●Wall layers ?Wall layersThin cells stacked along the walls, where the velocity changes fastest. Fewer than planned show up at sharp edges and complex corners: friction and heat transfer there are less accurate.thin cells along the walls; fewer than planned where the surface is sharp or complex3.0 of 3 on average
●y⁺ on the walls (mean) ?y⁺ on the wallsThe first cell's distance from the wall in viscous units. The wall functions used here want about 30–300; below 5 also works with k-ω SST; 5–30 is the least accurate band.the wall functions used here want about 30 to 300; below 5 also works with k-ω SST; 5 to 30 is the least accurate band1 285 (min 279.9, max 7 841)

Fluid region

●Fluid regionsized by Laminaro (COST 732 guidance: about 5 heights upstream, 15 downstream, blockage below 3 %)
●Backflow at outlet ?Backflow at an outletFlow coming back in over part of an outlet: the outlet is too close to a change of section or to a wake, and its condition distorts the result.flow coming back in at the outlet means the outlet is too close to a change of section or to the wake0 % of its area

Physics

●Simulated as ?Simulated asyour choice in 6 Run: the solver looks for one time-averaged flowsteady
●Flow found ?Flow foundfrom the run: the residuals fell low and the key results settledsteady
●Turbulence model ?Turbulence modelLaminar below Re ≈ 2 000 in a duct; k-ω SST the general choice for turbulent flow; k-ε realizable a robust older model. Between 2 000 and 4 000 every model is uncertain.Re ≈ 4.9·10⁶: turbulentk-ω SST (automatic)
●Inlet turbulencesuggested by Laminaro (5 % in ducts, 1 % in free air)

Every check on this page is made by Laminaro's code from this run's own files (solver logs, the mesh report, the saved fields); the guidance values are common CFD practice.