Particles have no radius, they are not volumes... particles are nodal points were quantities are computed However a volume is associated to the particles, that is dp*dp*dp being dp the initial distance between particles when they are created at t=0

Thanks. But if it has no radius, what is this “ const float over_lap=1.0f*float(Dp)-rad; //-(ri+rj)-|dij| if(over_lap>(-tensip/kn)){ //-Contact.” in in file JSphCpu.cpp. The over_lap was cauculated by particles radius. Could you explain the "float(Dp)" and "rad" to me in above equation.

Thanks, Ahsry. The rad is the direct distance, which is the center distance of the two particles, right? The dp is equal to the sum of the radius of the two particles, right?

dp is the initial distance between particles introduced in the xml file (the initial resolution). The SPH particles have no radius, but have smoothing length (radius of influence, h) as the Prof. told you.

You might have seen some runs for SPH on youtube that represent the particles as spheres. this is just a visualization which is useful in case of multi resolution problems. DualSPHysics uses single resolution for all particles.

## Comments

However a volume is associated to the particles, that is dp*dp*dp being dp the initial distance between particles when they are created at t=0

Regards

“ const float over_lap=1.0f*float(Dp)-rad; //-(ri+rj)-|dij| if(over_lap>(-tensip/kn)){ //-Contact.” in in file JSphCpu.cpp.

The over_lap was cauculated by particles radius. Could you explain the "float(Dp)" and "rad" to me in above equation.

over_lap = dp - rad

You might have seen some runs for SPH on youtube that represent the particles as spheres. this is just a visualization which is useful in case of multi resolution problems. DualSPHysics uses single resolution for all particles.