Centrifugal Settling Time Calculator
Estimate radial sedimentation time of a small dense sphere in a rotating liquid under creeping-flow Stokes drag.
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Result
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Calculation steps
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How to calculate
Integrate the radius-dependent Stokes terminal velocity while keeping the angular speed and properties constant.
dr/dt=(ρp−ρf)d²ω² r/(18μ); time=18μ ln(r2/r1)/((ρp−ρf)d²ω²)
Worked example
Doubling particle diameter quarters the ideal settling time; doubling rotor speed also quarters time in this low-Reynolds-number model.
Assumptions and input details
Require outward travel and particle density greater than liquid. Maximum modeled particle Reynolds number must be ≤0.1. Isolated spherical particles, no Brownian diffusion, hindered settling, transient slip or rotor-specific geometry; not a centrifuge operating recommendation.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
One revolution is 2π radians or 360 degrees. One minute is 60 seconds, so 1 rpm = 2π/60 rad/s. Rotational frequency in hertz counts revolutions per second.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
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Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
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