Description
Return Stokes settling speed and its particle Reynolds number.
Particle and droplet terms depend on size representation, weights, density, drag and logarithmic-bin conventions. A spherical growth or low-Reynolds approximation is a local model term rather than a measured size distribution, composition or health/exposure assessment.
Return Stokes settling speed and its particle Reynolds number.
When to use this tool
Use Cloud Droplet Terminal Drag Regime Term when checking the stated particle, droplet, drag, growth or bin-basis convention.
How to use the tool and how it works
- Enter radius, dropletDensity, airDensity, gravity, dynamicViscosity. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read stokesSpeed, reynolds. Use the output convention below.
Return Stokes settling speed and its particle Reynolds number. Require radius >= 0, dropletDensity >= airDensity >= 0, gravity/viscosity > 0; speed = 2*(rhoDrop-rhoAir)*g*r²/(9*mu), Reynolds = 2*r*rhoAir*speed/mu.1
Stokes drag describes a sphere in an appropriate viscous-flow regime. The low-Reynolds assumption must be checked separately before using a derived transport scale.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| radius | Radius | Required. Finite number; minimum 0. |
| dropletDensity | Droplet Density | Required. Finite number. |
| airDensity | Air Density | Required. Finite number; minimum 0. |
| gravity | Gravity | Required. Finite number; strictly above 0. |
| dynamicViscosity | Dynamic Viscosity | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| stokesSpeed | Stokes Speed | Required. Finite number. |
| reynolds | Reynolds | Required. Finite number. |
{
"input": {
"radius": 0.01,
"dropletDensity": 1000,
"airDensity": 1,
"gravity": 10,
"dynamicViscosity": 1
},
"output": {
"stokesSpeed": 0.222,
"reynolds": 0.004440000000000001
}
}Limitations and assumptions
- Stokes drag requires a suitably small Reynolds number and ideal spherical creeping flow; no regime correction or actual cloud observation is supplied.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use verified particle measurements and an appropriate complete distribution/transport model with justified material, shape and flow assumptions for atmospheric inference.
References
Similar or alternative tools
- Cloud Droplet Effective Area Term
Return weighted projected area and effective droplet radius.
- Aerosol Stokes Relaxation Time Term Tool
Calculate aerosol stokes relaxation time term from explicit caller-supplied inputs.