This was a 2-year long project funded by a life-long national program for new researchers (EDBM34). The research team included:

• Assoc. Prof. Onoufrios Haralampous – Principal investigator
• Dr Chris Dritselis – Senior researcher
• Dr Marios Mastrokalos – New researcher
• Dr Fotini Tzorbatzoglou – New researcher

The project dealt with with the performance of partially Failed Particulate Filters, often found in older vehicles due to inadequate maintenance or tampering of the exhaust system. Experimental and computational methods were applied at the smallest relevant scale to clarify the necessary flow and filtration phenomena and furthermore to quantify the effects in terms of diminished filtration efficiency. Interestingly additional filtration phenomena were identified in the intact and damaged DPFs, besides the prevailing deep-bed and surface filtration mechanism due to wall flow, while it was shown that prediction of pressure drop and filtration efficiency in an intact/damaged DPF under real-driving conditions is possible despite the difficulties.

The project involved the development of crossfire, a software library, which facilitates the coupling of OpenFOAM with other CAE tools. In this case OpenFOAM was coupled with exothermia suite (formerly axisuite) in order to model for exhaust aftertreatment systems. Specifically the following functionalities were implemented:

• Preprocessing
  • 3d mesh generation of exhaust system using simple geometrical parameters for standard components (cylindrical substrates, axisymmetric cones, curved or straight cylindrical pipes)
  • Definition of physicochemical model and numerical method parameters in OpenFOAM files
• Transient simulation with a customized OpenFOAM solver taking into account
  • momentum balance using an equivalent porous medium for the substrates (flow-through or wall-flow)
  • energy balance with pipe heat losses and source terms for the convection and chemical reactions in the substrates
  • mass balances of gaseous and solid species (soot and ash) with source terms for chemical reactions, absorption and filtration in the monoliths
• Post-processing
  • Reading and analysis of OpenFOAM results

The project was funded by Exothermia SA. The development of the library and the management of the project was undertaken by Onoufrios Haralampous with the assistance of Dimitrios Mastellos. On behalf of Exothermia SA, Dr Theodoros Atmakidis was responsible for the collaboration and integration in exothermia suite.