implements BasalFrictionRelation to provide a power law More...

#include <BasalFrictionRelation.H>

Inheritance diagram for BasalFrictionPowerLaw:

Collaboration diagram for BasalFrictionPowerLaw:

Public Member Functions
	BasalFrictionPowerLaw (Real a_m, Real a_fastSlidingSpeed=-1.0, Real a_highThickness=-1.0, bool a_includeEffectivePressure=false)

virtual	~BasalFrictionPowerLaw ()

virtual void	computeAlpha (FArrayBox &a_alpha, const FArrayBox &a_basalVel, const FArrayBox &a_C, const Real &a_scale, const LevelSigmaCS &a_coords, const DataIterator &a_dit, int a_level, const Box &a_box) const
	Computes cell-centered effective basal friction coeffcient $\alpha$ such that $\tau_b = \alpha (u_b, C) u_b$ . More...

BasalFrictionRelation *	getNewBasalFrictionRelation () const
	creates a new copy of subclass objects. More...

virtual Real	power () const

Public Member Functions inherited from BasalFrictionRelation
virtual	~BasalFrictionRelation ()

virtual void	updateThermodynamics (Vector< LevelData< FArrayBox > * > *a_tillWaterDepth)

virtual void	computeDissipation (FArrayBox &a_dissipation, const FArrayBox &a_basalVel, const FArrayBox &a_C, const Real &a_scale, const LevelSigmaCS &a_coords, const DataIterator &a_dit, int a_level, const Box &a_box) const
	Compute cell-centered dissipation rate . More...

Additional Inherited Members
Static Public Member Functions inherited from BasalFrictionRelation
static BasalFrictionRelation *	parse (const char *a_prefix, int a_recursion)
	Run-time configuration of BasalFrictionRelation objects. More...

Detailed Description

implements BasalFrictionRelation to provide a power law

$\tau_b = - C h_{ab}^n |u_b|^{m-1} u_b$

where $tau_b$ is the basal traction, $C$ is a coefficient not dependent on velocity, $h_{ab}$ is the thickness above flotation, $u_b$ is the basal velocity, and $n,m$ are exponents. Typically $m \leq 1$ .

gives a linear viscous sliding law
is often used (e.g in the MISMIP tests)

An optional factor $(|u_b|/|u_r| + 1)^{-m} )$ is available (see Joughin 2019) that lead $d|T_b|/d|u| \rightarrow -> 0$ as $|u| \rightarrow \infty$

An alternate version of the above, $N (N_r^{1/m} |u_b|/|u_r| + N^{1/m} )^{-m} )$ is available

Run-time configuation is carried out in BasalFrictionRelation::parse. If the string A.B.basalFrictionRelation = powerLaw is found, the expected form is

BasalFrictionPowerLaw.m = <float. e,g 0.3333 for m = 1/3>
BasalFrictionPowerLaw.includeEffectivePressure = <bool>
BasalFrictionPowerLaw.fastSlidingSpeed = <float. e.g 300 for Joughin 2019>
BasalFrictionPowerLaw.highThickness = <float. e.g 1e2 for ~100 kPa>

if includeEffectivePressure, $n = m$ so that there is a dependence on the thickness over flotation $h_ab$ . Otherwise, $n = 0$ . Do not use this option!

Constructor & Destructor Documentation

◆ BasalFrictionPowerLaw()

BasalFrictionPowerLaw::BasalFrictionPowerLaw	(	Real	a_m,
		Real	a_fastSlidingSpeed = `-1.0`,
		Real	a_highThickness = `-1.0`,
		bool	a_includeEffectivePressure = `false`
	)

inline

◆ ~BasalFrictionPowerLaw()

virtual BasalFrictionPowerLaw::~BasalFrictionPowerLaw ( )

inlinevirtual

References BasalFrictionRelation::computeAlpha().

Member Function Documentation

◆ computeAlpha()

void BasalFrictionPowerLaw::computeAlpha	(	FArrayBox &	a_alpha,
		const FArrayBox &	a_basalVel,
		const FArrayBox &	a_C,
		const Real &	a_scale,
		const LevelSigmaCS &	a_coords,
		const DataIterator &	a_dit,
		int	a_level,
		const Box &	a_box
	)		const

virtual

Computes cell-centered effective basal friction coeffcient $\alpha$ such that $\tau_b = \alpha (u_b, C) u_b$ .

Parameters

a_alpha	effective basal friction coefficient based on the local velocity field.
a_basalVel	Cell-centered basal velocity field.
a_C	Cell-centered coefficient field
a_coords	whole level geometry data
a_dit	index needed to retrieve data from a_coords
a_box	cell-centered box over which to do this computation