1. What is a Pressure Coefficient?

Definition: The pressure coefficient (C_p) is a dimensionless number that describes the relative pressure throughout a flow field in fluid dynamics.

Purpose: It's used to compare pressure distributions in different flow situations, particularly in pipe flow and aerodynamics.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( C_p \) — Pressure coefficient (dimensionless)
• \( P \) — Static pressure at the point of interest (Pa)
• \( P_0 \) — Reference pressure (Pa)
• \( \rho \) — Fluid density (kg/m³)
• \( v \) — Flow velocity (m/s)

Explanation: The numerator represents the pressure difference from reference, while the denominator is the dynamic pressure of the flow.

3. Importance of Pressure Coefficient

Details: C_p helps engineers analyze pressure distributions, predict flow separation points, and design efficient piping systems and aerodynamic surfaces.

4. Using the Calculator

Tips: Enter the absolute pressure, reference pressure (often freestream or static pressure), fluid density (1000 kg/m³ for water), and flow velocity. Density and velocity must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a negative C_p mean?
A: Negative values indicate pressure lower than the reference pressure, common in high-velocity regions.

Q2: What reference pressure should I use?
A: Typically use the freestream or static pressure. For pipe flow, often use atmospheric pressure (101325 Pa) or upstream pressure.

Q3: What's a typical C_p range?
A: Values typically range from -3 to +1, but can vary widely depending on flow conditions.

Q4: Can I use this for compressible flow?
A: This formula is for incompressible flow. For compressible flow, additional factors must be considered.

Q5: Why is density important in this calculation?
A: Density affects the dynamic pressure component, which normalizes the pressure difference in the coefficient.