Glen-type ice deformation law
An isotropic incompressible Glen-type model relates deviatoric stress τ to strain rate by ε̇ᵢⱼ=Aτ_e^(n−1)τᵢⱼ, where τ_e=√(τ:τ/2),A>0 and n>0.
Key knowledge
An isotropic incompressible Glen-type model relates deviatoric stress τ to strain rate by ε̇ᵢⱼ=Aτ_e^(n−1)τᵢⱼ, where τ_e=√(τ:τ/2),A>0 and n>0. This nonlinear viscous closure quantifies internal ice deformation. Its material factor depends on temperature and other ice-state properties; the common choice n≈3 is a calibrated approximation rather than a universal exponent.
Values and equations
ε̇ᵢⱼ=Aτ_e^(n−1)τᵢⱼ; τ_e=√(τ:τ/2)
- ε̇ᵢⱼ
- strain-rate tensor components s⁻¹
- τᵢⱼ,τ_e
- deviatoric stress tensor and effective stress Pa
- A
- Glen material factor on the stated time-unit convention Pa⁻ⁿ s⁻¹
- n
- empirical stress exponent 1
Conditions and scope
- Use the same effective-stress/strain-rate convention and the isotropic coaxial rheology. The displayed coefficient form applies forτ_e>0; setε̇=0 atτ=0 by continuous extension for all n>0. A has units Pa⁻ⁿs⁻¹ for SI strain rates.
- Fabric anisotropy, impurities, water content, damage and alternative creep mechanisms can require adapted laws. This bulk deformation law does not by itself predict basal sliding or calving.
Sources · 1
References
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Evidence and review
Read actual tensor/effective-invariant and Glen relationships, including ε̇_e=(τ_e/B)^n; substituted A=B⁻ⁿ and checked dimensions. The exponent is explicitly empirical, not an immutable property of all natural ice. No whole110-page source inspection claim.
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Entry details
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- uni-earth-glen-ice-rheology
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- core.1
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