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The Kinematic Viscosity Converter converts between all major units of kinematic viscosity — the ratio of dynamic viscosity to fluid density. Kinematic viscosity is crucial for fluid flow analysis, Reynolds number calculations, lubricant specification, and heat transfer modeling.
The SI unit is square meters per second (m²/s), but the CGS unit stokes (St) and its sub-unit centistokes (cSt) are far more common in practice. The relationship is: 1 St = 1 cm²/s = 10⁻⁴ m²/s and 1 cSt = 1 mm²/s = 10⁻⁶ m²/s. Water at 20°C has a kinematic viscosity of approximately 1.004 cSt (mm²/s).
Kinematic viscosity is essential for lubricant classification. The ISO viscosity grade (VG) system uses kinematic viscosity in cSt at 40°C: ISO VG 32 oil has 32 cSt, ISO VG 68 has 68 cSt, etc. Motor oil grades (SAE) are also defined by kinematic viscosity ranges. Understanding and converting these values is critical for selecting appropriate lubricants for machinery.
The Reynolds number — which determines whether flow is laminar or turbulent — uses kinematic viscosity: Re = vL/nu, where nu is kinematic viscosity in m²/s. This makes kinematic viscosity a key parameter in fluid dynamics, pipeline design, and aerodynamics.
The converter normalizes to m²/s. Key factors: 1 St = 10⁻⁴ m²/s, 1 cSt = 10⁻⁶ m²/s = 1 mm²/s, 1 ft²/s = 0.09290304 m²/s.
Water at 20°C: 1.004 cSt = 0.01004 St = 1.004×10⁻⁶ m²/s. Motor oil (SAE 30) at 100°C: ~9.3-12.5 cSt. Air at 20°C: ~15.1 cSt (air is kinematically more viscous than water due to its low density).
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10⁻⁶ m²/s = 1 cSt (water ~20°C)
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100 cSt = 1 St
Kinematic viscosity = dynamic viscosity / density. It measures how quickly a fluid flows under gravity. Units: m²/s or centistokes (cSt). Higher values mean slower flow.
Multiply by 10⁻⁴. 1 stokes = 1 cm²/s = 10⁻⁴ m²/s. Example: 5 St = 5×10⁻⁴ m²/s.
Yes, exactly. 1 cSt = 1 mm²/s = 10⁻⁶ m²/s. These terms are used interchangeably.
At 20°C: ~1.004 cSt. At 25°C: ~0.893 cSt. At 40°C: ~0.658 cSt. At 100°C: ~0.295 cSt.
Re = velocity × length / kinematic viscosity. For pipe flow, Re < 2300 is laminar, Re > 4000 is turbulent. Kinematic viscosity must be in m²/s for SI calculations.
ISO VG grades match kinematic viscosity in cSt at 40°C: VG 32 = 32 cSt, VG 46 = 46 cSt, VG 68 = 68 cSt. Select based on equipment manufacturer's recommendation, operating temperature, and load.
It determines oil film thickness, pumping ability, and heat dissipation. Too thick: excessive friction and poor flow at startup. Too thin: inadequate protection under load.
Dynamic viscosity = kinematic viscosity × density. Example: oil with 100 cSt and density 0.88 g/cm³ → dynamic viscosity = 100 × 0.88 = 88 cP.
Saybolt Universal Seconds (SUS) is an older US viscosity unit measured by timing fluid flow through a calibrated orifice. It is approximately related to cSt by: cSt ≈ 0.226 × SUS - 195/SUS (for SUS > 100).
Yes, surprisingly. Air at 20°C: ~15.1 cSt vs water: ~1.0 cSt. Air's dynamic viscosity is much lower, but its very low density makes kinematic viscosity higher. This matters for aerodynamic Reynolds numbers.
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