Post on 06-Jul-2018
8/17/2019 Fin Program
1/2
n=input('Enter number of grid points');h=1/(n-1);M=zeros([1,n]);l=input('Enter length of fin');h=input('Enter convection coeeficient');k=input('Enter thermal conductivity');disp('1 Variable area fin');disp('2 constant area rectangular fin');disp('3 constant area traingular fin');op=input('Enter option number');switch op case 1 A=input('Enter area values for each grid point in a row vector'); P=input('Enter perimeter values for each grid point similarly'); disp('The reference values for area and perimeter is same as that'); disp('of the first grid point'); for i=1:n Astar(i)=(A(i)*P(1))/(A(1)*P(i)); end M(1)=(-Astar(3)+4*Astar(2)-3*Astar(1))/(2*h); M(n)=(3*Astar(n)-4*Astar(n-1)+Astar(n-2))/(2*h); for i=2:n-1 M(i)=(Astar(i+1)-Astar(i-1))/(2*h); end
beta=(h*P(1)*l*l)/(k*A(1)); fprintf('value of beta is %f',beta); case 2 b=input('Enter breadth of fin'); w=input('Enter width of fin'); peri=2*(b+w); for i=1:n Astar(i)=1; end beta=(h*peri*l*l)/(k*b*w); fprintf('Value of beta is %f',beta); case 3 area=input('Enter area of traingular fin');
side=((4*area)/3^0.5)^0.5; beta=(h*l*l*3*side)/(k*area); for i=1:n Astar(i)=1; endendfor i=1:n X(i)=Astar(i)/(h^2)-M(i)/(2*h);endY=-((2*Astar)/(h*h)+beta);Z=Astar/(h*h)+M/(2*h);Tf=zeros([1,n-1]);disp('T at first grid point is given to be 1');
Ti=1;lamda=zeros(n-1);d=zeros([1,n-1]);d(1)=-X(2);lamda(1,1)=Y(2);lamda(1,2)=Z(2);lamda(n-1,n-2)=X(n)+Z(n);lamda(n-1,n-1)=Y(n);j=1;for i=2:n-2
8/17/2019 Fin Program
2/2
lamda(i,j)=X(1+i); lamda(i,j+1)=Y(1+i); lamda(i,j+2)=Z(1+i); j=j+1;endB=diag(lamda);A1=diag(lamda(2:n-1,1:n-2));A=zeros([1,n-1]);for i=2:n-1 A(i)=A1(i-1);endC1=diag(lamda(1:n-2,2:n-1));C=zeros([1,n-1]);for i=1:n-2 C(i)=C1(i);endgamma=zeros([1,n-1]);phi=zeros([1,n-1]);gamma(1)=d(1)/B(1);phi(1)=B(1);for i=2:n-1 phi(i)=B(i)-(A(i)*C(i-1))/phi(i-1);endfor i=2:n-1
gamma(i)=(d(i)-(A(i)*gamma(i-1)))/(B(i)-(A(i)*C(i-1))/phi(i-1));endTf(n-1)=gamma(n-1);for i=n-2:-1:1 Tf(i)=gamma(i)-(C(i)*Tf(i+1))/phi(i);endT=[Ti,Tf];h=1/(n-1);x=zeros([1,n]);for i=1:n x(i)=(i-1)*h;enddisp(T)