fluidsim

name	fluidsim
description	Calculate Nusselt number for forced convection heat transfer. Use when computing dimensionless heat transfer coefficient, or analyzing convection heat transfer performance.

FluidSim: Nusselt Number Calculation

Overview

The Nusselt number (Nu) is a dimensionless parameter that characterizes convective heat transfer. It represents the ratio of convective to conductive heat transfer across a fluid boundary.

Formula

Nu = h × D / k

Where:

• h: convective heat transfer coefficient (W/m²·K)
• D: characteristic length (m)
• k: thermal conductivity (W/m·K)

Calculation

# Read input: h (W/m²·K), k (W/m·K), D (m)
with open("/root/input.txt") as f:
    lines = f.read().strip().split("\n")
    h = float(lines[0].strip())   # convective coefficient
    k = float(lines[1].strip())   # thermal conductivity
    D = float(lines[2].strip())   # characteristic length

# Calculate Nusselt number
Nu = h * D / k

# Output
with open("/root/output.txt", "w") as f:
    f.write(f"Nusselt number: {Nu:.2f}\n")

Output Format

Nusselt number: X.XX

Round to 2 decimal places.

Physical Interpretation

Nu Range	Interpretation
Nu ≈ 1	Pure conduction (no convection)
Nu ≈ 2–10	Laminar flow in ducts
Nu > 10	Turbulent forced convection

Key Reference

• Nu = h × D / k
• Units cancel to make Nu dimensionless
• Higher Nu means more effective convective heat transfer