Strouhal Number Calculator

What is a Strouhal Number Calculator?

A Strouhal Number Calculator is a tool used to compute the Strouhal number (St), which is a dimensionless number that describes oscillating flow dynamics, particularly in vortex shedding and fluid-structure interactions. It is given by:

where:

• St= Strouhal number (dimensionless)
• f= vortex shedding frequency (Hz)
• L= characteristic length (m) (e.g., diameter of a cylinder in flow)
• U= flow velocity (m/s)

The Strouhal number is critical in analyzing unsteady fluid flows, including vortex shedding, flapping wings, and pulsating flows.

Why Use a Strouhal Number Calculator?

A Strouhal number calculator is useful for:

• Predicting vortex shedding frequency, which affects aerodynamics and fluid-structure interactions.
• Designing structures (e.g., bridges, towers) to avoid resonance and structural vibrations due to wind or water flow.
• Analyzing bio-locomotion (e.g., swimming of fish, flapping of wings in birds and insects).
• Optimizing engineering designs related to fluid dynamics, such as cooling towers, chimneys, and aircraft wings.

How to Use a Strouhal Number Calculator?

1. Input the vortex shedding frequency f (in Hz).

2. Enter the characteristic length L (e.g., the diameter of a cylinder).

3. Input the flow velocity U (in m/s).

4. Compute using the formula:

   

5. Interpret Results:

   • A typical Strouhal number for cylinder flows is around 0.2.
   • If St is too high or too low, it may indicate irregular or unstable flow patterns.

When to Use a Strouhal Number Calculator?

• In fluid mechanics to study vortex-induced vibrations.
• In aerodynamics to analyze airflow over aircraft wings and turbines.
• In structural engineering to prevent wind-induced oscillations in bridges, chimneys, and skyscrapers.
• In bioengineering to study natural movement patterns like fish swimming or insect flapping.