糖心原创

Project description

 

Peat bogs grow very slowly, and a core drilled through one is read like a diary: the deeper you go, the older the peat and the further back in climate history. The standard model behind this is a simple ODE. New plant material arrives at the surface and then slowly decays. But a bog is soft and wet, and over thousands of years it can also creep. If it does, the diary gets rewritten. A short calculation already shows that a bog creeping uniformly produces exactly the same core as one whose growth rate changed over time, so the two cannot be told apart. Whether it creeps at all may depend on a threshold. Like toothpaste, peat can hold its shape until it is pushed hard enough, and only then flow. The project starts from ODE and PDE models you can analyse by hand. It asks which histories a core can reveal and which it hides, and builds up to models of peat as a wet solid that yields and slowly flows.