Transient CFD: How Valuable is it for Catalyst Design?

The design of the hot-end exhaust system dictates the performance of the exhaust system in terms of emissions, power loss and durability. The engine-out flow is highly transient and hot, and may place tremendous thermal and inertial loads on a catalyst. Therefore, time-dependent and detailed flow and thermal field simulation may be crucial. This study is geared towards assessing the value of transient flow simulations for close-coupled and underbody converters. For this purpose key parameters are defined and compared for similar sized close-coupled and underbody catalysts via transient and steady flow simulations.