Boundary Layer Thickness Calculator

How the Boundary Layer Thickness Calculator Works

This calculator estimates the boundary layer thickness for fluid flow over a flat plate, a crucial concept in fluid mechanics and aerodynamics.

Steps to Calculate Boundary Layer Thickness

1. Select a fluid from the dropdown menu or enter a custom kinematic viscosity.
2. Input the distance from the leading edge of the plate (x in meters).
3. Input the free-stream velocity of the fluid (U∞ in m/s).
4. Click "Calculate Thickness" to determine the boundary layer thickness.
5. The calculator will indicate whether the flow is laminar or turbulent and provide the transition point.

Common Fluids and Their Kinematic Viscosity Values

Fluid	Kinematic Viscosity (ν in m²/s)
Water (20°C)	1.0 x 10-6
Air (20°C)	1.5 x 10-5
Ethanol	1.1 x 10-6
Glycerin	0.89 x 10-6
Olive Oil	1.0 x 10-3
Vegetable Oil	0.9 x 10-3

Boundary Layer Thickness Equations

The boundary layer thickness (δ) can be calculated using the following equations:

1. Laminar Flow

For laminar flow, the boundary layer thickness is given by:

δ_laminar = 5 * √(ν * x / U_∞)

Where:

• δ_laminar = boundary layer thickness for laminar flow (m)
• ν = kinematic viscosity of the fluid (m²/s)
• x = distance from the leading edge of the plate (m)
• U_∞ = free-stream velocity of the fluid (m/s)

2. Turbulent Flow

For turbulent flow, the boundary layer thickness is approximated as:

δ_turbulent = 0.37 * x * (Re_x)^-1/5

Where:

• δ_turbulent = boundary layer thickness for turbulent flow (m)
• Re_x = Reynolds number, calculated as Re_x = (U_∞ * x) / ν

Note: This boundary layer thickness calculator is specifically designed for flow over a flat plate.