function U0=Nikuradse(Ub,Re)

R = [4e3;2.3e4;1.1e5;1.1e6;2.0e6;3.2e6];

exp = [6.0;6.6;7;8.8;10;10];

n = interp1(R,exp,Re,'spline');


%U_mean (U0) is calculated with U_bulk. We should have used U_center in
%sted.

U0 = Ub.*(n+1).*((2.*n)+1)./(2.*n.*n);