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# Difference between revisions of "AliDispersionControl"

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− | '''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]]. | + | '''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]]. It should be used with the sixth-digit of [[IM]] equal to 3 (fully implicit gravity wave term). |

== Version == | == Version == | ||

− | {{ | + | {{Version support box|version=55|relation=+|support=tp}} |

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

==Controlling Dispersive Behavior== | ==Controlling Dispersive Behavior== | ||

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For the following equation: | For the following equation: | ||

− | <math>Correction = 1 - Ma^2 | + | <math>Correction = 1 - \frac{Ma^2}{4} - {A_d}H^{B_d}</math> |

− | where Ma is the Mach number (<math>Ma = \frac{\sqrt | + | where Ma is the Mach number (<math>Ma = \frac{\sqrt{gH}}{Cs}</math>) and H is the total water depth. |

## Latest revision as of 21:46, 10 July 2020

**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. It should be used with the sixth-digit of IM equal to 3 (fully implicit gravity wave term).

## Version

ADCIRC version: | ≥ 55 |

Tech 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:

where Ma is the Mach number () and H is the total water depth.