Terminal Settling Velocity Calculator
This tool helps cleanroom process engineers quickly estimate dust fallout rates and vertical transport times for preliminary contamination control planning. It calculates the simplified Stokes settling velocity for micrometer particles in still air without complex slip correction parameters.
Formula Details:
The simplified Stokes settling velocity (V) is calculated using the formula:
V = (D_m² * ρ * g) / (18 * μ)
Where:
D_m= Particle Diameter in meters (input μm * 1e-6)ρ= Particle Density (kg/m³)g= Acceleration due to gravity (9.81 m/s²)μ= Dynamic viscosity of air (1.81e-5 Pa·s)
How To Use This Calculator
- Input the particle diameter in micrometers.
- Input the material density in kilograms per cubic meter.
- View the calculated settling velocity appear instantly.
- Note the gravity constant (9.81 m/s²) and viscosity (1.81e-5 Pa·s) used in the calculation below the result.
FAQ
Q: What exactly does this tool calculate?
A: It calculates the terminal settling velocity of a spherical particle in stagnant air assuming laminar flow conditions governed by Stokes Law.
Q: Does this tool apply Cunningham slip correction factors?
A: No, it intentionally uses the simplified Stokes equation without slip correction parameters to provide rapid preliminary estimations rather than high-precision CFD modeling.
Q: At what particle size does this calculation become unreliable?
A: Stokes Law generally starts to lose accuracy for particles larger than 100 μm due to turbulence; this tool includes a visual warning when you enter diameters beyond that threshold.
Q: How does settling velocity relate to ISO class limits?
A: While settling rate determines how fast particles drop out of suspension, you should use our ISO Cleanroom Particle Concentration Limit Calculator to verify compliance against standard Class 10/100 or ISO 14644 thresholds.