Source: https://guthlabs.ai/docs/instruments/stokes-law-settling-velocity-calculator/implementation/

instrument implementation / implementation-contract

# Stokes' Law Settling Velocity Calculator implementation

A source-bound implementation contract for Stokes' Law Settling Velocity Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-011

**Effect**: Computation or source lookup only

## Input and validation requirements

Zero viscosity produces division by zero in the settling-velocity formula and Reynolds-number calculation. The instrument specification does not state an input-rejection rule, so this case must be handled as undefined rather than converted to a numeric result.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "particle_radius_m": 0.00001,
    "particle_density_kg_per_m3": 2650,
    "fluid_density_kg_per_m3": 1000,
    "dynamic_viscosity_Pa_s": 0.001,
    "g_m_per_s2": 9.80665
  },
  "expected_outputs": {
    "settling_velocity_m_per_s": 0.0003595771667,
    "reynolds_number": 0.007191543333,
    "stokes_valid": true
  },
  "working": "Delta rho = 2650 - 1000 = 1650 kg/m³. r² = (0.00001)² = 1.0×10^-10 m². V = (2/9)×1650×9.80665×1.0×10^-10/0.001 = (2/9)×1.61809725×10^-6/0.001 = 3.595771667×10^-4 m/s. Re = 2×1000×3.595771667×10^-4×0.00001/0.001 = 0.007191543333. Since Re<1, the Stokes check passes."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/stokes-law-settling-velocity-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/stokes-law-settling-velocity-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/stokes-law-settling-velocity-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`