User Function Budd Sliding Relation

General Informations

  • USF Fortran File: USF_Sliding.f90
  • USF Name: Sliding_Budd
  • Required Input Variable(s): Vertical coord, z

General Description

This is a summary description. See comments in the code module for a more complete description.

Basal shear stress is given by:

tau_b = C.{u_b}^{m - 1} . u_b . Zab^{q}

where Zab is height above bouyancy, C is a friction coefficient, and m and q are exponents.

The parameters to be given (in the bed boundary condition) are:

  • Budd Friction CoefficientC
  • Budd Velocity Exponentm
  • Budd Zab Exponentq
  • Budd Linear Velocityu_{t0}
  • Budd Floatation

If Budd Floatation is set to true then the height above buoyancy will be based on the floatation condition instead of inferred from the effective pressure (i.e. depth is used instead of normal stress). Default is false.

References

Bill Budd's original work:

Budd, W., Keage, P. L., and Blundy, N. A.: Empirical studies of ice sliding, J. Glaciol., 23, 157–170, 1979.

Budd, W., Jenssen, D., and Smith, I.: A 3-dimensional time- dependent model of the West Antarctic Ice-Sheet, Ann. Glaciol., 5, 29–36, 1984.

Recent implementation in Elmer/Ice:

Gladstone, R.M., R.C. Warner, B.K. Galton-Fenzi, O. Gagliardini, T. Zwinger and R. Greve, 2017. Marine ice sheet model performance depends on basal sliding physics and sub-shelf melting, The Cryosphere, 11, 319-329, doi:10.5194/tc-11-319-2017 pdf

userfunctions/budd.txt · Last modified: 2017/11/27 08:27 by gag
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