Class: `PressureDropDarcy`

The PressureDropDarcy class calculates the pressure drop (ΔP) in a pipe using the Darcy–Weisbach equation.
It is part of the ProcessPI Calculations module and inherits from CalculationBase.

📖 Description

The Darcy–Weisbach equation is a fundamental relation in fluid dynamics for estimating pressure loss due to friction in pipes.
It is valid for both laminar and turbulent flows, making it more versatile than empirical formulas like Hazen–Williams.

This method requires knowledge of the Darcy friction factor, which may be obtained from correlations such as Moody chart or the Colebrook–White equation.

📊 Formula

Pressure Drop:

\[ \Delta P = f \cdot \frac{L}{D} \cdot \frac{\rho \cdot v^2}{2} \]

Where:

Symbol	Description	Units
\( \Delta P \)	Pressure drop	Pa
\( f \)	Darcy friction factor	–
\( L \)	Pipe length	m
\( D \)	Pipe diameter	m
\( \rho \)	Fluid density	kg/m³
\( v \)	Fluid velocity	m/s

⚙️ Inputs

friction_factor → Darcy friction factor (dimensionless)
length → Pipe length (m)
diameter → Pipe internal diameter (m)
density → Fluid density (kg/m³)
velocity → Fluid velocity (m/s)

📤 Output

Returns a Pressure object containing the pressure drop in Pascals (Pa).

🛠️ Methods

validate_inputs()
Ensures all required inputs (friction_factor, length, diameter, density, velocity) are provided.
Raises ValueError if any are missing.

calculate()
Performs the Darcy–Weisbach pressure drop calculation:

Retrieves the inputs
Applies the formula
Returns the result as a Pressure object

Returns:
Pressure: The computed pressure drop in Pascals.

💻 Example Usage

Using the PressureDropDarcy

from processpi.calculations import PressureDropDarcy
from processpi.units import Pressure, Length, Diameter, Density, Velocity, Dimensionless

# Define pipe and fluid properties
friction_factor = Dimensionless(0.02)     # Example Darcy friction factor
length = Length(100, "m")                 # Pipe length
diameter = Diameter(0.15, "m")            # Pipe diameter
density = Density(998, "kg/m3")           # Water density
velocity = Velocity(2.5, "m/s")           # Fluid velocity

# Create calculation instance
pd_calc = PressureDropDarcy(
    friction_factor=friction_factor,
    length=length,
    diameter=diameter,
    density=density,
    velocity=velocity
)

# Perform calculation
deltaP = pd_calc.calculate()

print(f"Pressure Drop (Darcy–Weisbach): {deltaP}")

**Using the CalculationEngine

from processpi.engine import CalculationEngine
from processpi.units import Pressure, Length, Diameter, Density, Velocity, Dimensionless

# Initialize engine
engine = CalculationEngine()

# Define pipe and fluid properties
friction_factor = Dimensionless(0.02)
length = Length(100, "m")
diameter = Diameter(0.15, "m")
density = Density(998, "kg/m3")
velocity = Velocity(2.5, "m/s")

# Perform Darcy–Weisbach pressure drop calculation using the engine
deltaP = engine.calculate(
    "pressure_drop_darcy",
    friction_factor=friction_factor,
    length=length,
    diameter=diameter,
    density=density,
    velocity=velocity
)

print(f"Pressure Drop (via Engine): {deltaP}")

Class: PressureDropDarcy