Add: include new +turbulence subpackage

[AlbertoCuadra]

Summary

This pull request introduces a comprehensive suite of tools to facilitate the analysis and decomposition of turbulent flows. Key additions include:

• The HelmholtzSolver class for performing Helmholtz decomposition.
• The TurbulenceSpectra class for analyzing energy spectra.
• Supporting utilities for handling velocity fields, validating computations, and visualizing results.
• Example demonstrating usage of HelmholtzSolver and TurbulenceSpectra classes.

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Key Features

1. HelmholtzSolver Class

• Implements Helmholtz-Hodge decomposition to separate 3D velocity fields into:
  • Solenoidal Component (divergence-free).
  • Dilatational Component (curl-free).
• Includes validation methods for:
  • Checking divergence-free and curl-free conditions.
  • Ensuring decomposition accuracy (relative error tolerance).
• Configurable properties:
  • tol0: Relative error tolerance.
  • Flags for detailed logging (FLAG_TIME, FLAG_CHECKS, FLAG_RESULTS).

2. TurbulenceSpectra Class

• Computes turbulence energy spectra using:
  • Spherical Averaging.
  • Cross-Plane Averaging (configurable axis selection: x, y, or z).
• Provides functions to:
  • Validate energy cascade properties.
  • Plot and visualize spectra.

3. VelocityField Class

Encapsulates 3D velocity field data (u, v, w) and provides:

• Methods for computing:
  • Magnitude.
• Utilities for:
  • Normalizing velocity fields.
  • Scaling velocity components.