How to add a new baryon field ============================= If you wish to add a new BaryonField array -- for instance, to track the Oxygen fraction -- you'll need to do a few things. #. Add it to the ``field_type`` structure #. Define it in your problem type. :ref:`AddingANewTestProblem`. #. Do something with it. :ref:`NewLocalOperator`. #. If you need to advect a species as a color field, you will have to investigate how that works. Specifically, the means of conservation -- by fraction of by density -- as well as the inputs into the hydro solver.