# Svaerd200711

### From NA-Wiki

Implicit-explicit schemes for flow equations with stiff source terms

Many problems in flow physics require models that take chemical reactions into account. This poses a fundamental problem when the models are discretized and solved numerically. The reaction time scale is typically many orders of magnitude smaller than the time scale of the flow. For such equations explicit schemes are ruled out due to the small time step requirements. We propose and analyze an implicit-explicit scheme for a benchmark model problem. The scheme is generalized to the reactive Euler equations and tested on a detonation shock wave. We conclude that the scheme efficiently computes the correct result.