CFD Calculator Tools | Vaibhav Hiwale

Reynolds Number

Determines the flow regime — laminar, transitional, or turbulent.

Re = ρ U L / μ = U L / ν

Fluid preset

Velocity U (m/s)

Length / Diameter L (m)

Kinematic viscosity ν (m²/s)

Geometry

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Reynolds number

Y⁺ First Cell Height

Estimates the wall-adjacent cell size required to achieve a target y⁺ value. Uses flat-plate Schlichting friction correlation.

Δy = y⁺ · μ / (ρ · u_τ) | u_τ = √(τ_w / ρ) | C_f ≈ 0.026 Re^−1/7

Fluid preset

Target y⁺

Freestream velocity U (m/s)

Reference length L (m)

Density ρ (kg/m³)

Dynamic viscosity μ (Pa·s)

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first cell height

Mach Number

Computes Mach number and classifies the compressibility regime.

Ma = V / a | a = √(γ R T)

Velocity V (m/s)

Temperature

Temperature unit

Gas

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Mach number

Hydraulic Diameter

Used as the characteristic length for non-circular ducts in Reynolds number calculations.

D_h = 4A / P_wet

Cross-section shape

Diameter D (m)

Width W (m)

Height H (m)

Outer diameter D_o (m)

Inner diameter D_i (m)

Side length a (m)

—

hydraulic diameter (m)

Engineering Unit Converter

Common unit conversions for CFD pre- and post-processing.

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