Public evidence

physics.fluid.gradual_contraction

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

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Verification

17/17 calculation tests · Production surface contract 3/3

Golden tests 2 / 2
Boundary tests 10 / 10
Property tests 5 / 5
Production surface contract 3 / 3
Engine tested Yes
Source checked Yes
Artifact integrity PASS
Production attestation Embedded snapshot: STALE · Last attested schema matched 1.0.0 snapshot / local build · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · Public/cache ✓ · Origin ✓ · Live production status PASS (0 stale; 163 CURRENT) @ 2026-09-17T13:12:27.589Z
Semantic contract PASS
Evidence attested at 2026-09-17T13:12:26.751Z
Last production check 2026-09-17T13:12:26.751Z
Public / cache PASS
Origin PASS
Supplemental domain review Not performed
Named expert review Not performed

release artifacts aligned PASS
schema valid input executes PASS
engine success output validates schema PASS

Fingerprint sha256:8c949a2cd78f6bdb29996178dab05dc8a10ba51f1e81fd21849416b8adaa04f9

Input schema sha256:0a98a436c7ed1874662c57bbc57d7b0c8b8ea185ac938829de8b6e4821ae7cf2 · Output schema sha256:be306b8b13ebad159fcb431f1d9ba3cdfacf9249ee684ec496d558e55a43da25 · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: gradual-contraction
Engine: gradual-contraction
Engine build: 2026-09-17
Evidence core: 2026-09-17T11:28:31.444Z
Rendered: 2026-09-17T12:57:09.950Z
Last reviewed: —

Assumptions

Conical contraction: h = K v2² / (2g); K = 0.5 sin(α) (1 − v1/v2); α wall half-angle; k and K reported, not inputs
Require 0 < α < 90°; α=90° is sudden contraction; default g=9.80665 m/s²; default ρ=1000 kg/m³; incompressible; v2 > v1
Not sudden contraction (C_c), not gradual expansion (v1−v2)², not minor-loss K given, not Darcy f, not orifice C_d, not Q=Av

Limitations

Conical contraction: h = K v2² / (2g); K = 0.5 sin(α) (1 − v1/v2); α is wall half-angle; k and K are reported, not inputs
Require 0 < α < 90°; α=90° is sudden contraction, not this page; default g=9.80665; default ρ=1000 for Δp; v2 > v1
Not sudden contraction (C_c), not gradual expansion (v1−v2)², not minor-loss K given, not Darcy f, not orifice C_d, not Q=Av

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

ISO 80000-4 — Mechanics — Length, speed, pressure, plane angle
Supports: h is a head; v is a speed; Δp is a pressure; α is a plane angle
Idelchik — Handbook of Hydraulic Resistance — Conical contractions
Supports: ζ = 0.5 sin(α) (1 − A2/A1) for a conical reducer, α wall half-angle from the axis

Published checks

Golden, boundary, and property cases included in this evidence build.

ID	Kind	Status	Detail
`golden-gct-h`	golden	pass	Expected h=0.006213607266760182 · v1=1 · v2=2 · k=0.06093467170257374 · K=0.03046733585128687 · dP=60.93467170257374 · mode=head · model=conical_contraction · Actual mode=head · h=0.006213607266760182 · v1=1 · v2=2 · k=0.06093467170257374 · K=0.03046733585128687 · alpha=0.12217304763960307 · alpha_deg=7
`golden-gct-dP`	golden	pass	Expected dP=60.93467170257374 · model=conical_contraction · Actual mode=pressure · h=0.006213607266760182 · v1=1 · v2=2 · k=0.06093467170257374 · K=0.03046733585128687 · alpha=0.12217304763960307 · alpha_deg=7
`boundary-gct-v2`	boundary	pass	Expected v2=2 · model=conical_contraction · Actual mode=velocity · h=0.006213607266760182 · v1=1 · v2=2 · k=0.06093467170257374 · K=0.03046733585128687 · alpha=0.12217304763960307 · alpha_deg=7
`boundary-gct-alpha`	boundary	pass	Expected alpha_deg=7 · model=conical_contraction · Actual mode=angle · h=0.006213607266760182 · v1=1 · v2=2 · k=0.06093467170257374 · K=0.03046733585128687 · alpha=0.12217304763960307 · alpha_deg=7
`boundary-gct-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-gct-K`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`boundary-gct-k`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`boundary-gct-Cc`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`boundary-gct-Q`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`boundary-gct-mode`	boundary	pass	Expected INVALID_MODE · Actual INVALID_MODE
`boundary-gct-zero`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`boundary-gct-wide`	boundary	pass	Expected VALUE_OUT_OF_RANGE · Actual VALUE_OUT_OF_RANGE
`property-gct-h`	property	pass	h=K v2²/(2g)
`property-gct-K`	property	pass	K=0.5 sin(α)(1−v1/v2)
`property-gct-roundtrip-v2`	property	pass	v2 invert
`property-gct-roundtrip-a`	property	pass	α invert
`property-gct-model`	property	pass	conical_contraction