Re: Nonlinear models

mw wrote:

Chaos theory & bifurcations may be of use. The alternative would be to
look at research work in the Financial field. There will surely be a
few appropriate non-linear pde's under research.

This area is called Econometrics.

http://en.wikipedia.org/wiki/Econometrics
http://en.wikipedia.org/wiki/Modeling_and_analysis_of_financial_markets
.