function fdissip = fDissipJR(phi, e_R)
% This function calculates the normalized dissipation rate from the 
% Jenkins & Richman (1985) theory.
% The normalized dissipation rate is defined as
% 
% fdissip = dissip / [rho_s / d * T^(3/2)]
%
% syntax:
%   fdissip = fDissipJR(phi, e_R)
%
% inputs: volume fraction phi and the coefficient of restitution e_R, 
%
% output: normalized viscosity feta, its size is [length(phi), length(e_R)]
%
Nphi = length(phi);
Ne = length(e_R);
feta = zeros(Nphi, Ne);

chi = chiCS(phi);
phiA = (phi.^2).*chi;

for i=1:Ne
    ei = e_R(i);
    fdissip(:,i) = 12/sqrt(pi)*(1-ei)*phiA;
end
