Hello Jie,
If I want to stimulate the binary neutron stars in the gas to see if there are some special phenomenon, such like the collision of two accretion disks, or when a wind blows in the process, what will happen, what should I do? how to modify the parameter file? Please give me some guides.
Sorry for the long delay in response. Your email was stuck in the spam filter.
Basically you will have to write some code to set up a system like this. If your additional matter (eg accretion disks) is tenuous enough to not affect gravity (much) you can just superpose the matter distribution that you want on initial data for binary neutron stars. You would likely do so by scheduling a function in INITIAL AFTER HydroBase_Initial . There are some examples of how to set up initial data on the wiki here: https://docs.einsteintoolkit.org/et-docs/adding_initial_data though it deals with initial data for vacuum simulations.
Yours, Roland