Verified calculation capability

Sudden contraction Calculation Capability

Vena-contracta h=(1/C_c−1)² v2²/(2g). Default C_c=0.62. Not expansion (v1−v2)², not minor-loss K given, not orifice C_d, not Q=Av. · Physics · Fluid

Capability ID physics.fluid.sudden_contraction · version 1.0.0

Open calculator REST API MCP Evidence Evidence JSON Review policy

Model

Head loss

Head loss: h = (1/C_c − 1)² v2² / (2g)
Loss coefficient: K = (1/C_c − 1)²
Vena-contracta speed: v_c = v2 / C_c
Pressure drop: Δp = ρ K v2² / 2

Solve modes: head · pressure · velocity · coefficient

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`v2`	Downstream speed in m/s. Required except velocity invert. Alternative: v2_m_s.	—	input / output
`v2`	Downstream speed in m/s (query/UI). REST may send v2.	m/s	input
`C_c`	Vena-contracta coefficient in (0, 1). Optional; default 0.62. Required except coefficient invert. Alternatives: Cc, vena.	—	input / output
`h`	Head loss in m. Required for velocity and coefficient invert. Alternatives: hm, h_m.	—	input / output
`h`	Head loss in m (query/UI). REST may send h.	m	input
`rho`	Density in kg/m³. Optional; default 1000.	—	input / output
`g`	Gravity in m/s². Optional; default 9.80665.	—	input / output
`K`	—	—	output
`v_c`	—	—	output
`dP`	—	—	output
`model`	—	—	output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

Vena-contracta sudden contraction: h = (1/C_c − 1)² v2² / (2g); default C_c=0.62; K = (1/C_c − 1)² is reported, not an input
Default g=9.80665 m/s²; default ρ=1000 kg/m³ for Δp = ρ K v2² / 2; incompressible; C_c in (0, 1)
Not sudden expansion (v1−v2)², not minor-loss K given, not Darcy f, not orifice C_d, not Q=Av

Not supported

sudden expansion (v1−v2)²
catalog minor-loss K
Darcy f
orifice C_d
Q=Av

Example

One numerical check. The calculator page holds worked steps and FAQ.

C_c=0.62 v2=1 → h=(1/0.62−1)²/(2g) K=(1/0.62−1)²

Open this example in the calculator

Trust

Review-policy: engine tested — automated tests, sources, version lock, and evidence published. Supplemental to CVP; not Domain Expert Review. See CVP and Review policy.

Tier: Engine tested — catalog token engine_tested
Calculation version: 1.0.0
Evidence tests: 18/18 calculation tests · golden 2/2 · boundary 11/11 · property 5/5
Engine tested: Yes
Source checked: Yes
Supplemental domain review: Not performed
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.0.0 (workspace artifacts agree)

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

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 3/3.

Tool id: sudden-contraction
Engine: sudden-contraction
REST: POST /api/v1/calc/sudden-contraction
MCP: execute_calculation with capability_id: "physics.fluid.sudden_contraction"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.0.0)
Versioned output schema: Immutable pin (1.0.0)

References

Human-readable sources plus CVP reference evidence classes.

Sources

ISO 80000-4 — Mechanics — Length, speed, pressure
Borda–Carnot equation — Sudden contraction / vena contracta

Try with an agent

Inspect this capability via same-origin MCP, then call execute_calculation.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"physics.fluid.sudden_contraction"}}}'

Inspect the trust tier and required assurance level before execution. Pin calculation_version (1.0.0) when reproducibility matters. Full protocol notes: MCP docs.