Modelling Fluid-Solid Interaction using SPH

I am a newbie here, so I apologize if my question seems weird. This is about my SPH simulator, which not be able to handle 开发者_运维知识库fluid-solid interaction yet. My simulator can simulate fluid well, but I got confused when I want to add a solid object during the simulation.

I've read many paper, and I got several conclusion in my mind, please correct me if I'm wrong,

1. Both of solid and fluid object are modeled with single particle system, which each object particle has own parameter value, like mass, mass density, artificial viscosity, etc.
2. In each time step, SPH loop procedure is computed as usual in both of object, means that each particle object can contribute to another particle object if they are in radius of h, regardless what kind is that particle.
3. The difference with system that contains only fluid particles, is in fluid-solid system, exists Elastic Force that computed only between solid object. This force is not computed for fluid particle.

That is. At last, the questions.

What about SPH specific parameters like smoothing length, radius of particle, etc? Are these different between solid and fluid when computing forces for each particle? What actually correct way when calculating forces for both kind of particle? Is it just compute it in single looping?

The papers I've read tells me the formula, but I think I need the basic idea first.

Thanks.