1. What is the Boundary Layer Height Equation?

The boundary layer height equation calculates the thickness of a boundary layer in fluid dynamics using diffusivity and time. It provides a simplified estimation of how far momentum, heat, or mass has diffused over a given period.

2. How Does the Calculator Work?

The calculator uses the boundary layer height equation:

Where:

• \( h \) — Boundary layer height (m)
• \( K \) — Diffusivity (m²/s)
• \( t \) — Time (s)

Explanation: The equation describes how the boundary layer grows with the square root of time, proportional to the square root of the diffusivity coefficient.

3. Importance of Boundary Layer Height Calculation

Details: Accurate boundary layer height estimation is crucial for analyzing fluid flow behavior, heat transfer rates, and mass diffusion processes in various engineering and environmental applications.

4. Using the Calculator

Tips: Enter diffusivity in m²/s and time in seconds. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What types of diffusivity does this equation use?
A: The equation can be applied to momentum, thermal, or mass diffusivity depending on the context of the boundary layer being analyzed.

Q2: What are typical values for diffusivity?
A: Diffusivity values vary widely: molecular diffusivity ~10⁻⁹ m²/s, thermal diffusivity ~10⁻⁷ m²/s, and momentum diffusivity ~10⁻⁶ m²/s for air/water.

Q3: When is this simplified equation applicable?
A: This equation provides a good approximation for laminar flow conditions and constant property fluids with no pressure gradients.

Q4: What are the limitations of this equation?
A: The equation doesn't account for turbulent flow, pressure gradients, variable properties, or complex boundary conditions.

Q5: How does boundary layer height relate to Reynolds number?
A: Boundary layer thickness decreases with increasing Reynolds number, transitioning from laminar to turbulent flow around Re~5×10⁵.