init_impl update WeertmanSliding ~WeertmanSliding

update() void pism::stressbalance::WeertmanSliding::update ( const Inputs &  inputs, bool  full_update  ) virtual Compute sliding velocity using a Weertman-style parameterization from [Tomkin2007], equation 5. \[ u_s = \frac{2 A_s \beta_c (\rho g H)^{n}}{N - P} \cdot |\nabla h|^{n-1} \cdot \nabla h, \] where \( A_s \) is the sliding parameter, \( \beta_c \) is a parameter capturing the effect of the presence of valley walls (set to 1 in this implementation), \( \rho \) is the ice density, \( H \) is the ice thickness, \( h \) is the ice surface elevation , \( n \) is the flow law exponent (usually 3), \( g \) is the acceleration due to gravity, \( N \) is the ice overburden pressure, \( P \) is the basal water pressure. With these modifications and noting that \( N = \rho g H \), the formula above becomes \[ u_s = \frac{2 A_s}{1 - k} \cdot (N |\nabla h|)^{n-1} \cdot \nabla h, \] where \( N = \rho g H \), \( P = k N \) (we assume that basal water pressure is a given fraction of overburden) This parameterization is used for areas of grounded ice where the base of the ice is temperate. Implements pism::stressbalance::ShallowStressBalance. Definition at line 74 of file WeertmanSliding.cc. References pism::Geometry::cell_type, pism::ParallelSection::check(), pism::array::diff_x_p(), pism::array::diff_y_p(), pism::stressbalance::Inputs::enthalpy, pism::ParallelSection::failed(), pism::stressbalance::Inputs::geometry, pism::array::Array3D::get_column(), pism::Geometry::ice_surface_elevation, pism::Geometry::ice_thickness, pism::k, pism::Component::m_config, pism::stressbalance::ShallowStressBalance::m_EC, pism::stressbalance::ShallowStressBalance::m_flow_law, pism::Component::m_grid, pism::stressbalance::ShallowStressBalance::m_velocity, pism::Vector2d::magnitude(), and n.