Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!cleary
From: cleary@cpsc.ucalgary.ca (John Cleary)
Newsgroups: comp.parallel
Subject: Re: scalability of n-cubes, meshes (was: IPSC Communications)
Summary: 3D meshes and heat
Message-ID: <7480@hubcap.clemson.edu>
Date: 18 Dec 89 14:00:44 GMT
Sender: fpst@hubcap.clemson.edu
Lines: 26
Approved: parallel@hubcap.clemson.edu

In article <7427@hubcap.clemson.edu>, landman@hanami.Eng.Sun.COM (Howard A. Landman x61391) writes:
> >In article <7274@hubcap.clemson.edu> gene@cs.bu.edu (Gene Itkis) writes:
> >%One problem with 3D mesh is that as the processors work the heat is
> >%generated(*).....
> 
It worth noting however that the temperature of a 3D cube rises very slowly
with the number of nodes.  The heat lost by radiation (probably the only
feasible mechanism in the limit) is porportional to A*T^4 where A is the
surface area and T is the temperature.  If the radius of the 3D body is R then
A scales as R^2 and the number of processors (N) and hence the total heat (per
unit time) as R^3.  The result is that T scales as N^(1/12) pretty slow.

Of course if you could carry some of the heat away with neutrinos then 
you could build a big one before the temperature got too high :-)


	John G. Cleary
	Department of Computer Science
	University of Calgary
	2500 University Drive 
	N.W. Calgary
	Alberta T2N 1N4
	Canada

	cleary@cpsc.UCalgary.ca
	Phone: (403)282-5711 or (403)220-6087