RND_EDGE_SCREEN

Overview

Calculate the loss coefficient for a round edged wire screen or bar screen.

Excel Usage

=RND_EDGE_SCREEN(alpha, Re, angle)

• alpha (float, required): Fraction of screen open to flow, [-]
• Re (float, required): Reynolds number of flow through screen (D = space between rods), [-]
• angle (float, optional, default: 0): Angle of inclination (0 = straight, 90 = parallel to flow), [degrees]

Returns (float): Loss coefficient K, [-], or error message (str) if input is invalid.

Examples

Example 1: Basic case (alpha=0.5, Re=100)

Inputs:

alpha	Re
0.5	100

Excel formula:

=RND_EDGE_SCREEN(0.5, 100)

Expected output:

2.1

Example 2: With angle (alpha=0.5, Re=100, angle=45)

Inputs:

alpha	Re	angle
0.5	100	45

Excel formula:

=RND_EDGE_SCREEN(0.5, 100, 45)

Expected output:

1.05

Example 3: Low Reynolds number (Re=20)

Inputs:

alpha	Re
0.3	20

Excel formula:

=RND_EDGE_SCREEN(0.3, 20)

Expected output:

13.1444

Example 4: High Reynolds number (Re=400)

Inputs:

alpha	Re
0.7	400

Excel formula:

=RND_EDGE_SCREEN(0.7, 400)

Expected output:

0.5412

Python Code

from fluids.filters import round_edge_screen as fluids_round_edge_screen

def rnd_edge_screen(alpha, Re, angle=0):
    """
    Calculate the loss coefficient for a round edged wire screen or bar screen.

    See: https://fluids.readthedocs.io/fluids.filters.html#fluids.filters.round_edge_screen

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

    Args:
        alpha (float): Fraction of screen open to flow, [-]
        Re (float): Reynolds number of flow through screen (D = space between rods), [-]
        angle (float, optional): Angle of inclination (0 = straight, 90 = parallel to flow), [degrees] Default is 0.

    Returns:
        float: Loss coefficient K, [-], or error message (str) if input is invalid.
    """
    try:
      # Validate and convert alpha
      try:
        alpha = float(alpha)
      except (ValueError, TypeError):
        return "Error: alpha must be a number."

      # Validate and convert Re
      try:
        Re = float(Re)
      except (ValueError, TypeError):
        return "Error: Re must be a number."

      # Validate and convert angle
      try:
        angle = float(angle)
      except (ValueError, TypeError):
        return "Error: angle must be a number."

      # Validate ranges
      if alpha < 0.05 or alpha > 0.8:
        return "Error: alpha must be between 0.05 and 0.8."
      if Re <= 0:
        return "Error: Re must be positive."
      if angle < 0 or angle > 90:
        return "Error: angle must be between 0 and 90 degrees."

      result = fluids_round_edge_screen(alpha=alpha, Re=Re, angle=angle)
      if result != result or result in (float('inf'), float('-inf')):
        return "Error: Result is not finite."
      return float(result)
    except Exception as e:
      return f"Error: {str(e)}"

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