CAVITATION

Overview

The CAVITATION function calculates the Cavitation number (Ca), a dimensionless number used in fluid dynamics to characterize the potential for cavitation in a flowing fluid. Cavitation occurs when the local pressure in a fluid drops below its vapor pressure, leading to the formation of vapor bubbles. The Cavitation number is defined as:

where:

• $P$ is the local (internal) pressure (Pa)
• $P_{sat}$ is the vapor pressure of the fluid (Pa)
• $\rho$ is the fluid density (kg/m³)
• $V$ is the fluid velocity (m/s)

A lower Cavitation number indicates a higher likelihood of cavitation. This parameter is important in the design of pumps, turbines, and propellers to avoid damage from cavitation.

For more information, see the fluids.core documentation  and the fluids GitHub repository .

This example function is provided as-is without any representation of accuracy.

Usage

To use the function in Excel:

=CAVITATION(P, Psat, rho, V)

• P (float, required): Internal pressure in Pascals (Pa).
• Psat (float, required): Vapor pressure in Pascals (Pa).
• rho (float, required): Fluid density in kilograms per cubic meter (kg/m³).
• V (float, required): Fluid velocity in meters per second (m/s).

The function returns a single value (float): the Cavitation number (dimensionless), or an error message (string) if the input is invalid or out-of-range.

Examples

Example 1: Standard Water Flow

In Excel:

=CAVITATION(200000, 10000, 1000, 10)

Expected output:

Example 2: High Velocity

In Excel:

=CAVITATION(250000, 15000, 950, 20)

Expected output:

Example 3: Low Pressure

In Excel:

=CAVITATION(120000, 10000, 998, 8)

Expected output:

Example 4: High Vapor Pressure

In Excel:

=CAVITATION(300000, 50000, 1020, 15)

Expected output:

Python Code

import micropip
await micropip.install('fluids')
from fluids.core import Cavitation as fluids_cavitation
 
def cavitation(P, Psat, rho, V):
    """
    Calculate the Cavitation number (Ca) for a flowing fluid.
 
    Args:
        P: Internal pressure in Pascals (Pa).
        Psat: Vapor pressure in Pascals (Pa).
        rho: Fluid density in kilograms per cubic meter (kg/m³).
        V: Fluid velocity in meters per second (m/s).
 
    Returns:
        Cavitation number (dimensionless) as a float, or an error message (str) if input is invalid.
 
    This example function is provided as-is without any representation of accuracy.
    """
    try:
        P = float(P)
        Psat = float(Psat)
        rho = float(rho)
        V = float(V)
    except Exception:
        return "Invalid input: could not convert arguments to float."
    if V == 0 or rho == 0:
        return "Invalid input: velocity and density must be nonzero."
    try:
        result = fluids_cavitation(P, Psat, rho, V)
    except Exception as e:
        return f"Error: {str(e)}"
    return round(result, 5)

Live Notebook

Edit this function in a live notebook .

Live Demo