The Oregonator

The Oregonator is a series of ODE’s describing a chemical reaction for ions. The general form of the ODE’s are (ref: Haiere, Norsett & Wanner, Solving ODE’s, part I):

 

 

 

 The Oregonator is a set of stiff ODE’s that have significantly different settling times for each of the variables, thus making it numerically challenging to solve. The W-method with the error estimate and the adaptive step-size control was put to test to solve the Oregonator problem with the following values:

 

The initial values used were y1(0)=y3(0)=400, y2(0)=1. The solution is shown below with a log-scale for the ordinate.