Euler 's Method for falling velocity ode..

Mass = 100/6*pi*0.04^3;
g=9.8;
A=0.25*pi*0.04^2;
U=0.0001;
dt = 0.01;
for t=0:dt:15-dt
    Re = 1.25*0.04*U/0.000015;
    CD=24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6);
    dUdt = g - (0.5*1.25*U(end)^2*A*CD)/Mass
    U(end+1)=U(end)+dUdt*dt
end
plot(0:dt:15, U)

error occurs in "U(end+1)=U(end)+dUdt*dt" sentence

I can't find any problem... Could you find problem in this code? I think 'Re' and 'CD' also looks doubtful..

Thanks for reading my quenstion

Answer 1

[Sugar Daddy]

Mass = 100/6*pi*0.04^3;
g=9.8;
A=0.25*pi*0.04^2;
U=0.0001;
dt = 0.01;
for t=0:dt:15-dt

Error is in this line as the U size increase Re size increases so put U(end) here too

%     Re = 1.25*0.04*U/0.000015; % Error 
Re = 1.25*0.04*U(end)/0.000015; % Correct

    CD=24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6);
    dUdt = g - (0.5*1.25*U(end)^2*A*CD)/Mass
    U(end+1)=U(end)+dUdt*dt
end
plot(0:dt:15, U)

[James]

thank you so much for giving me a reason!!