kyriazis@pawl20.pawl.rpi.edu (George Kyriazis) (04/04/88)
Hello world. I am about to start a project about simulating rigid bodies or fluids made out of particles, and I want to ask some questions before beginning. I think these are the right newsgroups, so that's why I started from here. What I like to know is references on where I can find more info about that subject. The problem is not simply simulating the movements of these particles. What is the problem is that the naive method is of O(n*n) (calculating n-1 forces exerted to every particle). Since I am not into physics very much, what I'd like to find is any simplifications on that. I heard something about calculating the forces from the nearest neighbors only. Are there any more opinions on that? Also calculating closest neighborhood in 2-d or even 3-d for the next time step from the previous neighborhood is difficult. Are there any data structures or algorithms that can (easily) handle this kind of thing? Lastly, what kind of forces (other than the attractive and repulsive forces between atoms) do I have to take into account? Maybe there are any moments also? Thanks in advance for the help.. ******************************************************* *George C. Kyriazis * Gravity is a myth *kyriazis@mts.rpi.edu or kyriazis@rpitsmts.bitnet * \ / *kyriazis@life.pawl.rpi.edu kyriazis@docsun.rpi.edu * \ / *Electrical and Computer Systems Engineering Dept. * || *Rensselear Polytechnic Institute, Troy, NY 12180 * Earth sucks *******************************************************
blob@calgary.UUCP (Brian Wyvill) (04/06/88)
In article <609@imagine.PAWL.RPI.EDU>, kyriazis@pawl20.pawl.rpi.edu (George Kyriazis) writes: > > Hello world. I am about to start a project about simulating rigid > bodies or fluids made out of particles, ........ > What is the problem is that the naive method is of O(n*n) > (calculating n-1 forces exerted to every particle). Since I am not into > physics very much, what I'd like to find is any simplifications on that. If you are worried about calculating the force exterted by every particle on every other particle, try dividing the world uniformly into a 3D grid of voxels. (You may find octree subdivison useful too.) Into each voxel place a reference to all the particles that can affect that volume. Now you only have to consider how particles affect each other within a voxel. Of course you may find that all the particles are placed in every voxel in which case you are back where you started! -- Brian Wyvill ..!{ubc-vision,ihnp4}!alberta!calgary!blob
kyriazis@pawl13.pawl.rpi.edu (George Kyriazis) (04/17/88)
Thanks everybody that sent me information about the particle systems query I posted a few days ago. I am really sorry I didn't reply to someone from SUN that sent me a whole program, but somehow mail couldn't get through to him. I will keep everyone informed with whatever I do on that subject (as many people asked for that). ******************************************************* *George C. Kyriazis * Gravity is a myth *kyriazis@mts.rpi.edu or kyriazis@rpitsmts.bitnet * \ / *kyriazis@life.pawl.rpi.edu kyriazis@docsun.rpi.edu * \ / *Electrical and Computer Systems Engineering Dept. * || *Rensselear Polytechnic Institute, Troy, NY 12180 * Earth sucks *******************************************************