function vs = setvel(r,rv)
% calculate settling velocity of an array
%     input- r rms radius   cm
%            rv cons volume radius, cm
%            setcon   constant with all terms calc in tcalc.m
%     output- v settling velocity cm/s 
%  use formulation calculated on 18 july 1994 
%                           
global setcon
vs = setcon * rv .^ 3 ./ r;
