Help with this Integration problem

clear; clc; close all
 
% Part A: water 
 
R = .5; %ft
L = 30; %ft
cP = 1.32/12; %psi/ft
mu = 578/12; %lbm/(ft*s)
r = linspace(0,R,100); %m^3*atm/(kg-mol*K)
v_r = ((-R^2)/(4*mu))*(cP/L)*(1-((r.^2)/(R^2)));
 
% integration 
 
Iv_r = (trapz(R,v_r.*r));
Vtop_avg= 2*pi*Iv_r;
Vbot_avg= pi*R^2;
V_avg= (Vtop_avg)/(Vbot_avg)
 
% Part B: for MIL-M-5606 hydraulic fluid 
 
R = .5; %ft
L = 30; %ft
cP = 1.32/12; %psi/ft
mu = 6.95e7/12; %lbm/(ft*s)
r = linspace(0,R,100); %m^3*atm/(kg-mol*K)
v_r = ((-R^2)/(4*mu))*(cP/L)*(1-((r.^2)/(R^2)));
 
% integration 
 
Iv_r = (trapz(R,v_r.*r));
Vtop_avg= 2*pi*Iv_r;
Vbot_avg= pi*R^2;
V_avg= (Vtop_avg)/(Vbot_avg)

The avgs should be 304 and .0025 but I am not getting those values

[Jan]

All we see is the code, which does not produce the wanted result. There is no chance to find a problem, because we do not have any information about what you want to solve. I do not even know, what "The avgs" are.

So curently the question is equvalent to:

a = 2;
b = 3;
c = a+ b;
% I get the result 5, but I need to get 17.3.

So please edit the question and provide the details.

[Star Strider]

If you have a PDF of the equations you’re using and the integrations, attaching it would help. Your code runs without error, so that means you haven’t coded your equations correctly.

[Torsten]

Iv_r = trapz(r,v_r.*r);

instead of

Iv_r = (trapz(R,v_r.*r));

Best wishes

Torsten.