Class containing physical constants and the constitutive relation describing till for SSA. More...

#include <basal_resistance.hh>

Inheritance diagram for IceBasalResistancePlasticLaw:

Public Member Functions
	IceBasalResistancePlasticLaw (PetscScalar regularizationConstant, bool pseudoPlastic, PetscScalar pseudoExponent, PetscScalar pseudoUThreshold)
virtual PetscErrorCode	printInfo (int verbthresh, MPI_Comm com)
virtual PetscScalar	drag (PetscScalar tauc, PetscScalar vx, PetscScalar vy)
	Compute the drag coefficient for the basal shear stress.
virtual void	dragWithDerivative (PetscReal tauc, PetscScalar vx, PetscScalar vy, PetscScalar drag, PetscScalar ddrag) const
virtual	~IceBasalResistancePlasticLaw ()
Public Attributes
PetscReal	plastic_regularize
PetscReal	pseudo_q
PetscReal	pseudo_u_threshold
bool	pseudo_plastic

Detailed Description

Class containing physical constants and the constitutive relation describing till for SSA.

This pseudo -plastic type can actually describe anything from linearly viscous till to purely plastic till.

Definition at line 29 of file basal_resistance.hh.

Constructor & Destructor Documentation

IceBasalResistancePlasticLaw	(	PetscScalar	regularizationConstant,
		bool	pseudoPlastic,
		PetscScalar	pseudoExponent,
		PetscScalar	pseudoUThreshold
	)

Definition at line 23 of file basal_resistance.cc.

References plastic_regularize, pseudo_plastic, pseudo_q, and pseudo_u_threshold.

virtual ~IceBasalResistancePlasticLaw ( ) [inline, virtual]

Definition at line 39 of file basal_resistance.hh.

Member Function Documentation

PetscScalar drag	(	PetscScalar	tauc,
		PetscScalar	vx,
		PetscScalar	vy
	)		`[virtual]`

Compute the drag coefficient for the basal shear stress.

The basal shear stress term $\tau_b$ in the SSA stress balance for ice is minus the return value here times (vx,vy). Thus this method computes the basal shear stress as

$\tau_b = - \frac{\tau_c}{|\mathbf{U}|^{1-q} U_{\mathtt{th}}^q} \mathbf{U}$

where $\tau_b=(\tau_{(b)x},\tau_{(b)y})$ , $U=(u,v)$ , $q=$ pseudo_q, and $U_{\mathtt{th}}=$ pseudo_u_threshold. Typical values for the constants are $q=0.25$ and $U_{\mathtt{th}} = 100$ m/a.

The linearly-viscous till case pseudo_q = 1.0 is allowed, in which case $\beta = \tau_c/U_{\mathtt{th}}$ . The purely-plastic till case pseudo_q = 0.0 is also allowed; note that there is still a regularization with data member plastic_regularize.