1. What is Turbulent Boundary Layer Thickness?

Turbulent Boundary Layer Thickness is the distance normal to the wall to a point where the flow velocity has essentially reached the 'asymptotic' velocity, or 99 percent of freestream velocity in turbulent flow conditions.

2. How Does the Calculator Work?

The calculator uses the turbulent boundary layer thickness formula:

Where:

• \( \delta_T \) — Turbulent boundary layer thickness (m)
• \( x \) — Distance on X-axis from leading edge (m)
• \( Re_T \) — Reynolds Number for turbulent flow

Explanation: This empirical formula describes the growth of turbulent boundary layer thickness along a flat plate, where the thickness increases with distance from the leading edge and decreases with increasing Reynolds number.

3. Importance of Boundary Layer Calculation

Details: Accurate boundary layer thickness calculation is crucial for predicting flow separation, heat transfer rates, drag forces, and overall aerodynamic performance in engineering applications involving turbulent flows.

4. Using the Calculator

Tips: Enter the distance from leading edge in meters and the Reynolds number for turbulent flow. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between laminar and turbulent boundary layers?
A: Laminar boundary layers have smooth, orderly flow with lower thickness growth rate, while turbulent boundary layers have chaotic, mixing flow with faster thickness growth but better resistance to separation.

Q2: At what Reynolds number does flow become turbulent?
A: For flow over a flat plate, transition to turbulence typically occurs around Reynolds number 5×10⁵, though this can vary with surface roughness and flow disturbances.

Q3: How does boundary layer thickness affect drag?
A: Thicker boundary layers generally result in higher skin friction drag, though turbulent boundary layers can sometimes reduce pressure drag by delaying flow separation.

Q4: Are there limitations to this formula?
A: This formula is empirical and works best for zero-pressure-gradient turbulent boundary layers on smooth flat plates. It may not be accurate for curved surfaces or flows with significant pressure gradients.

Q5: How does surface roughness affect boundary layer thickness?
A: Surface roughness typically increases boundary layer thickness and can trigger earlier transition from laminar to turbulent flow, affecting both the growth rate and characteristics of the boundary layer.