RND_EDGE_MESH
Computes the pressure-loss coefficient K for rounded-edge open mesh and net geometries using empirical subtype-specific correlations based on open-area fraction.
For each supported subtype, K is modeled as a quadratic function of blockage (1-\alpha):
K = a(1-\alpha) + b(1-\alpha)^2
where coefficients (a,b) depend on mesh pattern. An inclination-angle correction is then applied relative to approach flow.
The source correlation is intended for turbulent flow and high-open-area meshes, typically 0.85 \leq \alpha \leq 1, with K referenced to the upstream approach velocity.
Excel Usage
=RND_EDGE_MESH(alpha, mesh_type, angle)alpha(float, required): Fraction of net/screen open to flow, [-]mesh_type(str, optional, default: “diamond pattern wire”): Type of mesh patternangle(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.
Example 1: Diamond pattern wire mesh at alpha 0.96
Inputs:
| alpha |
|---|
| 0.96 |
Excel formula:
=RND_EDGE_MESH(0.96)Expected output:
0.02888
Example 2: Diamond pattern wire mesh inclined at 33 degrees
Inputs:
| alpha | angle |
|---|---|
| 0.96 | 33 |
Excel formula:
=RND_EDGE_MESH(0.96, 33)Expected output:
0.0203133
Example 3: Round bar screen subtype at alpha 0.9
Inputs:
| alpha | mesh_type |
|---|---|
| 0.9 | round bar screen |
Excel formula:
=RND_EDGE_MESH(0.9, "round bar screen")Expected output:
0.097
Example 4: Knotted net subtype at alpha 0.95
Inputs:
| alpha | mesh_type |
|---|---|
| 0.95 | knotted net |
Excel formula:
=RND_EDGE_MESH(0.95, "knotted net")Expected output:
0.04725
Python Code
Show Code
from fluids.filters import round_edge_open_mesh as fluids_round_edge_open_mesh
def rnd_edge_mesh(alpha, mesh_type='diamond pattern wire', angle=0):
"""
Calculate the loss coefficient for a round edged open net or screen mesh.
See: https://fluids.readthedocs.io/fluids.filters.html#fluids.filters.round_edge_open_mesh
This example function is provided as-is without any representation of accuracy.
Args:
alpha (float): Fraction of net/screen open to flow, [-]
mesh_type (str, optional): Type of mesh pattern Valid options: Diamond Pattern Wire, Round Bar Screen, Knotted Net, Knotless Net. Default is 'diamond pattern wire'.
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 angle
try:
angle = float(angle)
except (ValueError, TypeError):
return "Error: angle must be a number."
# Validate ranges
if alpha < 0.85 or alpha > 1:
return "Error: alpha must be between 0.85 and 1."
if angle < 0 or angle > 90:
return "Error: angle must be between 0 and 90 degrees."
# Validate mesh_type
valid_types = ['round bar screen', 'diamond pattern wire', 'knotted net', 'knotless net']
if mesh_type not in valid_types:
return f"Error: mesh_type must be one of {valid_types}."
result = fluids_round_edge_open_mesh(alpha=alpha, subtype=mesh_type, 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)}"