Are there any simulations that can be obtained that use smooth particle hydrodynamics and can be configured to include different initial conditions? I wish to simulate planetary collisions and their impact. I wish to exactly replicate the following link.
I would recommend MPA Garching's Gadget code for cosmological simulations of structure formation. It's primarily gravitational, but I do believe you can include gas effects as well:
I don't know if this is what is commonly used for tasks such as yours, but it might be a place to start looking.