STOKES_NUMBER

Excel Usage

=STOKES_NUMBER(V, Dp, D, rhop, mu)
  • V (float, required): Characteristic velocity [m/s]
  • Dp (float, required): Particle diameter [m]
  • D (float, required): Characteristic diameter [m]
  • rhop (float, required): Particle density [kg/m^3]
  • mu (float, required): Fluid viscosity [Pa*s]

Returns (float): Stokes number [-]

Examples

Example 1: Example from docstring

Inputs:

V Dp D rhop mu
0.9 0.00001 0.001 1000 0.00001

Excel formula:

=STOKES_NUMBER(0.9, 0.00001, 0.001, 1000, 0.00001)

Expected output:

0.5

Example 2: Higher velocity increases Stokes number

Inputs:

V Dp D rhop mu
1.8 0.00001 0.001 1000 0.00001

Excel formula:

=STOKES_NUMBER(1.8, 0.00001, 0.001, 1000, 0.00001)

Expected output:

1

Example 3: Larger particle diameter increases Stokes number

Inputs:

V Dp D rhop mu
0.9 0.00002 0.001 1000 0.00001

Excel formula:

=STOKES_NUMBER(0.9, 0.00002, 0.001, 1000, 0.00001)

Expected output:

2

Example 4: Denser particles increase Stokes number

Inputs:

V Dp D rhop mu
0.9 0.00001 0.001 2000 0.00001

Excel formula:

=STOKES_NUMBER(0.9, 0.00001, 0.001, 2000, 0.00001)

Expected output:

1

Python Code

from fluids.core import Stokes_number as fluids_Stokes_number

def stokes_number(V, Dp, D, rhop, mu):
    """
    Calculate the Stokes number.

    See: https://fluids.readthedocs.io/fluids.core.html#fluids.core.Stokes_number

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

    Args:
        V (float): Characteristic velocity [m/s]
        Dp (float): Particle diameter [m]
        D (float): Characteristic diameter [m]
        rhop (float): Particle density [kg/m^3]
        mu (float): Fluid viscosity [Pa*s]

    Returns:
        float: Stokes number [-]
    """
    try:
        V_val = float(V)
        Dp_val = float(Dp)
        D_val = float(D)
        rhop_val = float(rhop)
        mu_val = float(mu)
    except Exception:
        return "Error: All parameters must be numeric values."

    if D_val == 0 or mu_val == 0:
        return "Error: D and mu must not be zero."

    try:
        result = fluids_Stokes_number(V_val, Dp_val, D_val, rhop_val, mu_val)
        return float(result)
    except Exception as e:
        return f"Error: {str(e)}"

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