Linear basal drag law
= Linear basal drag law
{title2=$\sigma_b=\mu\beta u_b$}
A linear basal drag law has resisting traction $-\mu\beta u_b$, with $\beta>0$ of dimension inverse length. It idealizes lubrication by <subglacial till> and is equivalent to a <Navier slip boundary condition> of <slip length> $1/\beta$ when the ice is a <Newtonian fluid>. It is a constitutive idealization, not a universal sliding law.