Verified calculation capability

Darcy–Weisbach Calculation Capability

Pipe head loss hf = f L v²/(2 g D) and Δp = ρ g hf from a given Darcy friction factor. Does not solve Colebrook for f. · Physics · Fluid

Capability ID physics.fluid.darcy_weisbach · version 1.0.0

Open calculator REST API MCP Evidence Evidence JSON Review policy

Model

Head loss

Head loss: hf = f L v² / (2 g D)
Pressure drop: Δp = ρ g hf

Inputs / Outputs

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

Symbol	Quantity	Unit	Role
`f`	Darcy friction factor. Not solved from Re on this page.	—	input / output
`L`	Pipe length in metres.	—	input / output
`v`	Mean velocity in m/s.	—	input / output
`D`	Pipe inner diameter in metres.	—	input / output
`rho`	Fluid density in kg/m³.	—	input / output
`g`	Gravity in m/s². Default 9.80665.	—	input / output
`hf`	—	m	output
`dP`	—	Pa	output
`model`	—	—	output

Assumptions / Validity

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

Assumptions

Incompressible
Constant Darcy friction factor
Circular full-flow pipe
g = 9.80665 m/s² unless given
Does not solve Colebrook for f
Not Hazen–Williams or minor-loss K

Not supported

Colebrook solve for f
laminar 64/Re
Hazen–Williams
minor-loss K
compressible flow
Q=Av

Example

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

f=0.02 L=10 v=2 D=0.1 rho=1000 → Δp=4000 Pa

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: 11/11 calculation tests · golden 1/1 · boundary 5/5 · 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Production attestation: Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status PASS (0 stale; 164 CURRENT) @ 2026-09-16T06:44:24.909Z
Semantic contract: PASS
Evidence attested at: 2026-09-16T06:44:24.203Z
Last production check: 2026-09-16T06:44:24.203Z
Public / cache: —
Origin: —

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 4/4.

Tool id: darcy-weisbach
Engine: darcy-weisbach
REST: POST /api/v1/calc/darcy-weisbach
MCP: execute_calculation with capability_id: "physics.fluid.darcy_weisbach"
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 — Pressure and hydraulic head
White, F.M. Fluid Mechanics — pipe flow — Darcy–Weisbach equation

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.darcy_weisbach"}}}'

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