Hi Arash, Sorry for a slow response. Has anyone sent you any comments. Are you sure that it is your chemical reaction that is running slowly or is it the 3D run. Typically we have to use better preconditioner to make the 3D code run better. Could that be the issue? Cheers, Spencer. On 27 Mar 2019, at 00:13, Arash Nouri <nouri.aarash@gmail.com<mailto:nouri.aarash@gmail.com>> wrote: Hi all, I've added an equation of state and a chemical reaction to the compressible flow solver via couple of FORTRAN subroutines. In my 2D simulations, everything is cool and I've almost linear scalability up to 2K processors. However, my 3D simulations are surprisingly slow. Do you have any idea about probable reasons? What I basically do for the chemical reaction is: I call a FORTRAN subroutine in DoOdeRhs to get the required forcing terms for energy and species equations. Best, Arash --------------------------------- Arash G. Nouri Research Scientist Computational Modeling & Simulation (http://cmsp.pitt.edu/) 1127 Benedum Hall University of Pittsburgh Pittsburgh, PA 15261, USA E-mail: arn36@pitt.edu<mailto:arn36@pitt.edu> _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users Spencer Sherwin FREng, FRAeS Head, Aerodynamics, Director of Research Computing Service, Professor of Computational Fluid Mechanics, Department of Aeronautics, s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> South Kensington Campus, Phone: +44 (0)20 7594 5052 Imperial College London, Fax: +44 (0)20 7594 1974 London, SW7 2AZ, UK http://www.imperial.ac.uk/people/s.sherwin/