Body face
- study of how materials flow and deform under applied stress
- Newtonian fluid: viscosity independent of shear rate (water, honey)
- non-Newtonian: shear-thinning (paint), shear-thickening (dense particle suspensions)
- yield stress: no flow below a threshold stress (toothpaste)
- viscoelastic: elastic on short timescales, viscous on long ones (Deborah number = relaxation time / observation time)
- e.g. glacier ice, Earth’s mantle (solid for seismic waves, convecting over millions of years)