fix the error please . AS SOON AS POSSIBLE !!1 PLEASE

Question

Vetrichelvan Pugazendi 2018-4-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397341-fix-the-error-please-as-soon-as-possible-1-please

编辑： Walter Roberson 2018-4-26

HERES THE CODE

% TO CALCULATE MOMENTUM AND THERMAL BOUNDARY LAYER OVER A FLAT PLATE
%BY SHOOTING TECHNIQUE AND 4TH ORDER RUNGA KUTTA METHOD
Etta_max = 10;
h = 0.01;           %the step size
n_max = Etta_max/h;
f = zeros(n_max,1);
G = zeros(n_max,1);
H = zeros(n_max,1);
Error = 0.000001;
H_I =zeros (2,1);
H_I(2) =5;
G_steady = zeros(2,1);
i = 0;
%SOLUTION OF MOMENTUM BOUNDARY LAYER
while (abs(G(size(G))-1)>Error), %For shooting
    if i == 1,
        G_steady(1)= G(n_max);
        H(1) = H_I(2);
    end
    else
        H(1)=(H_I(1)+H_I(2))/2;
end
for n    =  1:n_max     %Runga Kutta 4
    k1    =  h*G(n);
    l1    =  h*H(n);
    m1    =  -(h/2)*f(n)*H(n);
    %
    k2    =  h*(G(n)+l1/2);
    l2    =  h*(H(n)+m1/2);
    m2    =  -(h/2)*(f(n)+ k1/2)*(H(n)+ m1/2);
    k3    =  h*(G(n)+ l2/2);
    l3    =  h*(H(n)+ m2/2);
    m3    =  -(h/2)*(f(n)+ k2/2)*(H(n)+ m2/2);
    k4  =   h*(G(n)+ l3);
    l4    =  -h*(H(n)+ m3) ;
    m4    =  -(h/2)*(f(n)+ k3)*(H(n)+ m3);
      f  (n+1)  =    f (n)  +  (l/6) * (k1 + 2* k2  + 2* k3 +  k4);
      G (n+1)  =    G (n)  +    (1/6) * (l1 + 2* l2  + 2* l3 +  l4);
      H (n+1)  =    H (n)  +    (l/6) * (m1 + 2* m2  + 2* m3 +  m4);
  end
  i = i+1;
  if  i>l,
      if G(n_max)<1,
          G_steady(1)=G(n_max);
          H_I(1)=H(1);
      else
          G_steadv(2)=G(n_max);
          H_I(2)=H(1);
      end
  end
  end
  plot(G,' r ' ) ;
  hold on;
  %-------------------------------------------------------------------
%SOLUTION OF THERMAL BOUNDARY LAYER
fprintf('Enter lamda = 0 for constant wall temperature.\n');
fprintf('Enter lamda = 0.5 for constant wall heat flux.\n');
lamda = input('Enter the value of lamda: ');
nue = input('Enter the value of kinematic viscocity of fluid (in SI unit):');
alpha = input('Enter the value of thermal diffusivity of fluid (in SI unit):');
Pr = nue/alpha;
theta = ones(n_max,1);
Y  = zeros(n_max,1);
theta_steady = zeros(2,1);
Y_I = ones(2,1);
Y_I(1) = -5; %INITIAL GUESS
Y(1) = Y_I(1);
i = 0;
while (abs(theta(n_max))>Error), %Shooting
    if i == 1,
        theta_steady(1)= theta(n_max);
        Y(1) = Y_I(2);
    end
    if i>1
        Y  (1) = (Y_I (1)+Y_I (2) ) /2;
    end
    for n = 1:n_max    %Runga Kutta 4
        p1 = h*Y(n);
        q1 = h*(lamda*Pr*G(n)*theta(n) - (Pr/2)*f (n)*Y(n));
          p2 = h*(Y(n)+q1/2);
          q2 = h*(lamda*Pr*G(n)* (theta(n)+p1/2) - (Pr/2)*f(n)*(Y(n)+ql/2))
          p3 = h*(Y(n)+ q2/2);
          q3 = h*(lamda*Pr*G (n)* (theta(n)+p2/2) - (Pr/2)*f(n)*(Y(n)+q2/2))
          p4 = h*(Y(n)+ q3);
          q4 = h*(lamda*Pr*G(n)* (theta(n)+p3) - (Pr/2)*f (n)*(Y(n)+q3));
          theta (n+1)  = theta (n)+ (1/6) * (p1+ 2*p2+ 2*p3+ p4);
          Y  (n+1) = Y(n)+ (1/5) * (q1+ 2*q2+ 2*q3+ q4) ;
      end
      i = i+1;
      %theta(n_max)
      if i>1,
          if theta(n_max)<0,
              theta_steady (1)=theta(n_max);
              Y_I(1)=Y(1);
          else
              theta_steady(2)=theta(n_max) ;
              Y_I(2)=Y(1);
          end
      end
  end
  %-----------------------------------------------------------------------
  theta_star = 1 - theta;
  plot(theta_star,'m');
  %---------------------------------------------------------------------
U_inf = input ('Enter the value of free stream velocity (in m/s) :');
u = U_inf*G;
% Checking correlation
if lamda ==0,
    T_w = input('Enter the wall temperature (in degree celcius):');
    T_inf = input('Enter the free stream temperature (in degree elecius):')
    T = T_inf + theta*(T_w - T_inf);
    A = abs(Y(1))
    B = 0.332*(Pr) ^ (1/3)
end
%------------------------------------------------------------------
%File printing and output segment
fid1 = fopen ('data1.txt' , 'w');
fprintf (fid1, 'SL.No.\t\tEtta\t\t f \t\t\t G \t\t\t H \t\t\tVelocity\n');
fid2 = fopen ('data2. txt' , 'w');
if lamda ==0,
    fprintf (fid2,'SL.No.\t Etta\t\t Theta\t\t\tY \t\t Temp\n');
else
    fprintf (fid2,'SL.No.\t Etta\t\t Theta\t\t\tY \n');
end
for i=1:40
    Etta = etaa_max/40* (i -1) ;
    k = Etta/h+1;
    fprintf (fid1, '%d \t\t %f \t\t %f \t\t %f \t\t %f \t\t %f \n', i , Etta, f(k), G(k) , H(k),u(k));
      if lamda==0,
          fprintf (fid2,' %d \t\t %f \t\t %f \t\t %f \t\t %f \n', i, Etta, theta(k), Y(k), T(k));
      else
          fprintf (fid2,' %d \t\t %f \t\t %f \t\t %f \n', i, Etta, theta(k), Y(k));
      end
  end
  fclose ('all');
  hold off;

2 个评论
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per isakson 2018-4-25

See TUTORIAL: how to ask a question (on Answers) and get a fast answer

John D'Errico 2018-4-25

编辑：Walter Roberson 2018-4-26

YES SIR! We will jump right to solving your problem. As soon as you give people a clue as to what the problems is, and as soon as someone feels like answering it.

If you want help, then make it easy for someone to help you. Tell people what the problem is. If you had an error, then show the COMPLETE text of the error.

https://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency

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Answer 1

Image Analyst 2018-4-25

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397341-fix-the-error-please-as-soon-as-possible-1-please#answer_317223

在 MATLAB Online 中打开

What's going on here:

%SOLUTION OF MOMENTUM BOUNDARY LAYER
while (abs(G(size(G))-1)>Error), %For shooting
    if i == 1,
        G_steady(1)= G(n_max);
        H(1) = H_I(2);
    end
    else
        H(1)=(H_I(1)+H_I(2))/2;
end