turbulence v3.2.3¶

Mercurial revision 5770:c90c3015e72d | 2026-05-22

Description¶

The turbulence program computes the vertical diffusivity associated with a current profile. It supports multiple diagnostic methods to analyze turbulence and diffusion coefficients based on input data.

Usage¶

turbulence -f FILE [OPTIONS]

Options¶

Option	Description
`-h`, `--help`	Print this help and exit.
`-f <file>`	Specify the input LGD file name. Required.
`-o <file>`	Specify the output file name.
`-d <n>`	Specify the time step (`dt`) for explicit time stepping (in seconds).
`-i <n>`	Number of iterations to compute TKE (Turbulent Kinetic Energy). Must be an integer.
`-t <n>`	Specify the diagnostic method (integer):
	`0` : Use a specified/hard-coded linear velocity profile.
	`1` (default) : Read an LGD file and use the Kepsilon turbulence model.
	`2` : Read an LGD file and use the Gaspar scheme.
	`5` : Read real velocity time series (not harmonic coefficients) and use the Kepsilon model.

Examples¶

Default Kepsilon Model¶

Run with default settings (Kepsilon model) on an LGD file:

turbulence -f input.lgd -o output.lgd

Custom Time Step and Iterations¶

Specify a time step of 10.0 seconds and 50 iterations:

turbulence -f input.lgd -o output.lgd -d 10.0 -i 50

Linear Velocity Profile¶

Use a hard-coded linear velocity profile:

turbulence -f input.lgd -o output.lgd -t 0

Gaspar Scheme¶

Use the Gaspar scheme for turbulence modeling:

turbulence -f input.lgd -o output.lgd -t 2

Real Velocity Time Series¶

Process real velocity time series (not harmonic coefficients):

turbulence -f velocity_data.lgd -o output.lgd -t 5 -i 100 -d 5.0

Environment Variables¶

This program does not explicitly rely on environment variables. However, it uses OpenMP for parallelization if compiled with OpenMP support. You can control parallel execution using standard OpenMP environment variables:

Variable	Description
`OMP_NUM_THREADS`	Number of threads to use for parallel execution.

Example:

OMP_NUM_THREADS=4 turbulence -f input.lgd -o output.lgd

Notes¶

Input File Format:

The input file (-f) must be in LGD format (a structured ASCII format for oceanographic data).
For -t 0, the program uses a hard-coded linear velocity profile.
For -t 1 or -t 2, the program reads harmonic coefficients from the LGD file.
For -t 5, the program reads real velocity time series (not harmonic coefficients).

Output:

The output file (-o) contains computed turbulence parameters (e.g., diffusion coefficients, TKE, etc.).
If no output file is specified, results are saved with a default name.

Performance:

For large datasets, adjust -i (iterations) and -d (time step) to balance accuracy and computation time.
Use OMP_NUM_THREADS to optimize performance on multi-core systems.

Diagnostic Methods:

Kepsilon (-t 1 or -t 5): A two-equation turbulence model for computing turbulent kinetic energy and dissipation rate.
Gaspar (-t 2): An alternative turbulence scheme for specific applications.