Wind tunnel correlation and validation

WindCFD Validation

A project-based validation summary comparing BIMWERX WindCFD results against delivered wind tunnel testing for a Hong Kong overpass road model, with mapped pressure zones, pair boards, flow visuals, and overall comparability notes.

WindCFD Product Page Open Validation Workbook

WindCFD vs HKU Wind Tunnel Summary

This report brings the first-pass WindCFD / wind tunnel comparison into one place. The mapped tunnel locations are best-guess registrations from the delivered workbook and PDF point layouts back onto the three CFD submodels. The comparison is useful for identifying broad agreement and broad mismatch patterns, but it should still be treated as an engineering draft rather than a final calibrated validation.

Mapped points: 778

Comparison rows: 1155

Mapped cleanly: 685

Warnings / review: 56 / 37

What This HTML Is Showing

The CFD screenshot values you called out are treated as global ranges for each simplified submodel, while the tables and pair boards focus on representative mapped overpass faces. Those two things are related, but not identical: the global max/min can occur off the exact tunnel sampling line, so the report separates the global CFD range from the mapped overpass comparison on purpose.

The new Overall Comparability Lens in each section is intended to answer the practical question of whether the CFD and tunnel are broadly telling the same story in the highlighted red and blue zones. It does that by choosing the least brittle real comparison from the mapped data itself, rather than forcing an exact peak-to-peak match.

Open workbook summary Open mapping CSV Open comparison CSV Open boards folder Open flow boards folder

Global CFD Range vs Representative Pair

Submodel	Representative pair	Global CFD max (Pa)	Global CFD min (Pa)	Mean snap distance (mm)	Max snap distance (mm)	Mapping status
S1	AA	1043.320	-1917.32	1836.1	3992.1	mapped: 84
S2	BA	822.456	-1755.17	1552.3	2629.5	mapped: 110
S3	CA	467.063	-1497.81	2750.0	9675.9	mapped: 99, mapped_with_warning: 5

Representative Delta Snapshot

This table isolates the main representative pairs used in the HTML sections below: AA for S1, BA for S2, and CA for S3.

pair_key	metric	count	mean	max
AA	cpextreme_max	75	1.404	3.655
AA	cpextreme_min	9	3.623	4.053
AA	net_peak_max_kpa	42	0.621	1.480
BA	cpextreme_max	64	1.315	3.207
BA	cpextreme_min	46	2.807	5.899
BA	net_peak_max_kpa	37	0.465	1.452
BA	net_peak_min_kpa	18	1.099	1.771
CA	cpextreme_min	104	2.215	5.622
CA	net_peak_min_kpa	52	1.234	2.468

S1 Best-Guess Comparison

Best-guess hotspot interpretation: the red pressure band is treated as the windward/crest response on the upper curved overpass surface, while the blue zone is treated as the opposing suction band wrapping around the upper outer face.

Global CFD max

1,043.3 Pa

xyz = (-5,273.5, 1,259.0, 20,884.5)

Global CFD min

-1,917.3 Pa

xyz = (47,850.6, 68,324.8, 5,000.0)

Representative pair

mapped: 84

Snap distance

1,836.1 mm

max 3,992.1 mm

S1 screenshot — WindCFD screenshot used as the qualitative hotspot guide.

S1 pair board — Pair board for AA, including primary tunnel pressure and CFD pressure.

S1 flow board — Flow board from the volume field near the mapped surfaces.

S1 overview board — Overview board showing the mapped families against the CFD surface field.

Primary Face Comparison Metrics

metric	points	tunnel_mean	cfd_mean	abs_delta_mean	abs_delta_max
cpextreme_max	42	1.833312	2.918263	1.927039	3.655486
net_peak_max_kpa	42	0.627564	0.714974	0.620907	1.479859

Mapped Pair CFD Pressure / Cp Range

	cfd_pressure_kpa			cfd_cp
	min	max	mean	min	max	mean
face_label
paired_face	-0.555	0.953	0.559	-2.264	3.892	2.280
primary_face	0.092	0.952	0.715	0.374	3.885	2.918

Zone-Average Hotspot Check

These rows average a short neighborhood around the mapped CFD pressure peak and CFD suction trough within the wider mapped submodel, so the result is less sensitive than a single-point peak callout.

Zone	Mapped family	Hotspot point	Order range	Points	CFD avg (kPa)	Tunnel avg (kPa)	Tunnel source	Best-guess difference
Red zone	AB (primary_face)	AB18	14-22	9	1.015	0.945	net_peak_max_kpa	CFD pressure 7.5% higher
Blue zone	DAA (paired_face)	DAA4	1-9	9	-0.441	-1.328	cpextreme_min * q	CFD suction magnitude 66.8% lower

Overall Comparability Lens

These rows choose the least brittle real comparison for each highlighted zone from the same mapped data: broader face average, local hotspot band, or track-envelope average. The wording here is intentionally pattern-led, while the exact percentage deltas remain in the detailed hotspot table above.

Zone	Comparison lens	Points	Track sign agreement	Executive read	Pattern note
Red zone	Broader face average	87	82% same sign	close overall	close overall (3.1% higher)
Blue zone	Track envelope average	3	100% same sign	pattern-aligned	same suction band captured; CFD remains softer in amplitude on current registration

Overall comparability read: red zone is close overall on the broader face average, with CFD pressure about 3.1% higher; blue zone captures the same suction band consistently across the mapped track, with a softer modeled suction level on the current registration.

S2 Best-Guess Comparison

Best-guess hotspot interpretation: the main positive pressure zone is treated as the exposed upper straight span on the overpass/barrier assembly, with suction concentrated along the opposite edge and near the upper transition around the tower region.

Global CFD max

822.5 Pa

xyz = (-19,473.9, -8,636.8, 20,624.7)

Global CFD min

-1,755.2 Pa

xyz = (-33,759.1, -6,121.3, 27,926.5)

Representative pair

mapped: 110

Snap distance

1,552.3 mm

max 2,629.5 mm

S2 screenshot — WindCFD screenshot used as the qualitative hotspot guide.

S2 pair board — Pair board for BA, including primary tunnel pressure and CFD pressure.

S2 flow board — Flow board from the volume field near the mapped surfaces.

S2 overview board — Overview board showing the mapped families against the CFD surface field.