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# AliDispersionControl

**Ali's Dispersion Correction** is a correction to the dispersive behavior of very long waves in a compressible ocean on an elastic Earth. It is intended to be used in lieu of the self-attraction and loading tide prescribed through the fort.24 file.

## Version

ADCIRC version: | ≥ 55: Technical Preview |

This is considered a technical preview in version 55. Theoretical work is still ongoing.

## Controlling Dispersive Behavior

The feature is triggered by the presence of the &AliDispersionControl namelist at the bottom of the fort.15 file. Here is an example of how this line is used (the following floats are the default values):

`&AliDispersionControl CAliDisp=T, Cs=1500.0, Ad = 0.0050189, Bd = 0.23394/`

`CAliDisp`

logical flag to turn Ali's dispersion correction on (F=false by default).`Cs`

is the speed of sound in water [m/s] for the Mach number based dispersive correction. Set Cs to a negative value to turn the Mach number based correction off.`Ad`

the power law constant.`Bd`

the power law exponent.

For the following equation:
**Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle Correction = 1 - \frac{Ma^2}{4} - {A_d}H^{B_d}}**

where Ma is the Mach number (**Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle Ma = \frac{\sqrt{gH}}{Cs}}**
) and H is the total water depth.