I have developed a code for thrombosis modeling, which involves a lot of Advection-Diffusion-Reaction (ADR) equations under influence of flow. For the Navier-Stokes calculations I use the Oasis solver, the rest of the model is implemented in a problem specific function. For solving the ADR equations I use NonLinearVariationalSolvers. I tried to speed up my simulations by running them in parallel, but they seem to slow down instead? The computer I use has 8 cores, but the simulation time becomes longer as I add cores. I run the simulations with:
mpirun -n 8 NSfracStep.py problem=thrombosis_model
Does anyone know what the cause could be of the slowing down simulation when they are performed in parallel?