Need help with an integral interval
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hey i have this matlab script that work fine, but i found out that my interval is wrong now i integrate from -d to a. in real i need from -d to a*sin(w*t) where d,a and w is known but t is variable or linspace from 0 to 30. see script bellow: PS need to change F at the bottom.
clear all
clear variables
clc
H100 = 28.6083; % Intermediate Water
C100 = 17.8718;
Tmin = 13.6365;
Tmax = 17.7395;
Tmean = 15.6880;
%--------------------------------------------------------------------------
d = 100; % water depth
T = Tmin; % wave period
a = H100/2; % or C100 % wave amplitude
g = 9.81; % acceleration of gravity
% x = direction of propagation
% t = time
w = 2*pi/T; % wave frequency
syms k
k1 = solve(g*k*tanh(k*d)-w^2 == 0, k);
k = sqrt(k1.^2); % wave number
L = simple(((g*T.^2)*tanh(k*d))/(2*pi)); % wave length
% Morison equation data
D = 1; % Diameter on column: D = 1m= drag, D = 5m= drag/mass, and D = 20m= mass
p = 1025;
Cm = 2;
Cd = 1.1;
%--------------------------------------------------------------------------
% Velocity = V % Acceleration = A
t = linspace(0,30);
x = 0;
syms z
V1 = (((a*k*g*cosh(k*(z+d)))/(w*cosh(k*d)))*sin(w*t-k*x)); % Extrapolation above free surface
V2 = ((a*k*g*cosh(k*(((z-a)/(1+a/d))+d)))/(w*cosh(k*d))*sin(w*t-k*x)); % Wheeler stretching
V3 = (((a*k*g*cosh(k*(0+d)))/(w*cosh(k*d)))*sin(w*t-k*x)); % z = 0 constant value used for surface
A1 = ((a*k*g*cosh(k*(z+d)))/(cosh(k*d)))*cos(w*t-k*x); % Extrapolation above free surface
A2 = ((a*k*g*cosh(k*(((z-a)/(1+a/d))+d)))/(cosh(k*d)))*cos(w*t-k*x); % Wheeler stretching
A3 = ((a*k*g*cosh(k*(0+d)))/(cosh(k*d)))*cos(w*t-k*x); % z = 0 constant value used for surface
%--------------------------------------------------------------------------
% Tmin for H100
Fm = (pi*p*Cm*A1*D.^2)/4;
Fd = ((p*Cd*D)/2)*V1.*(abs(V1));
F = int(Fm,z,-d,a*t)+int(Fd,z,-d,a*t);
[MaxValue_H100_Tmin_Extr, Index_At_F] = max(double(F))
t_Position_of_MaxValue_H100_Tmin_Extr = t(Index_At_F)
% i need to write somthing like( see bellow): but this makes an error.
%a1 = a*sin(w*t);
%F = int(Fm,z,-d,a1)+int(Fd,z,-d,a1);
4 Comments
Konstantinos Sofos
on 19 Mar 2015
What is the error? May you have to debug your script, so that you can understand what is going wrong with the dimensions...
ekko ekkosen
on 19 Mar 2015
Konstantinos Sofos
on 19 Mar 2015
To eval symbolic expressions to specific values of the symbolic variables you can try
F = eval('int(Fm,z,-d,a1)+int(Fd,z,-d,a1)')
ekko ekkosen
on 19 Mar 2015
Answers (0)
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