--- Welcome to the official ADCIRCWiki site! The site is currently under construction, with limited information. ---

# Difference between revisions of "NOLIBF"

NOLIBF is a parameter in the fort.15 file controlling the type of bottom stress parameterization used in a 2DDI ADCIRC run. This parameter must be specified but is ignored in a 3D run.

## Parameter Summary

The following table is a summary of possible NOLIBF values, description, details, and other necessary input parameters and files.

NOLIBF Value Description Details Other Required Inputs
0 linear bottom friction law uses a spatially constant linear bottom friction, ${\displaystyle \tau _{b}}$ of dimensions [1/T] FFACTOR
1 quadratic bottom friction law can specify a spatially constant or spatially varying dimensionless coefficient, ${\displaystyle C_{f}}$; in which ${\displaystyle \tau _{b}=C_{f}|U|/H}$ FFACTOR
2 hybrid nonlinear bottom friction law In deep water, the friction coefficient is constant and a quadratic bottom friction law results. In shallow water the friction coefficient increases as the depth decreases (e.g. as in a Manning-type friction law). The friction coefficient is determined as: FFACTOR=FFACTORMIN*[1+(HBREAK/H)**FTHETA]**(FGAMMA/FTHETA) FFACTORMIN, HBREAK, FTHETA, FGAMMA

## Usage Notes

In the NWP section, if the user selects quadratic_friction_coefficient_at_sea_floor, mannings_n_at_sea_floor, or chezy_friction_coefficient_at_sea_floor, then NOLIBF must be 1 (nonlinear friction formulation) since all those formulations are nonlinear. If the NOLIBF were anything other than 1, it is an error that will cause ADCIRC to stop.

For 3D ADCIRC runs, spatially varying bottom friction should be specified using the bottom_roughness_length fort.13 file nodal attribute.