
can it be possible to use odeVectorField
    9 vues (au cours des 30 derniers jours)
  
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syms f(x) g(x) h(x) Pr Nb Nt Le
[V] = odeToVectorField( diff(f,3) - diff(f)^2 + f * diff(f,2) == 0,diff(g,2) + Pr * ( f * diff(g) + Nb * diff(g)* diff(h)+ Nt * diff(g)^2) == 0,...
                                       diff(h,2) + Le * f * diff(h) + ( Nt/Nb ) * Pr * ( f * diff(g) + Nb * diff(g)* diff(h)+ Nt * diff(g)^2)== 0)
%%  I want to incorporate the expression of [V]  into below code, but I am getting wrong expression (not as  dydx  below) 
%%%  can it be used in   bvp 4c  code  and  in which  style
function main
Pr=10; Le=10; Nt=.1;Nb=.1;
xa=0;xb=6;solinit=bvpinit(linspace(xa,xb,1000),[0 1 1 1 0 0 0]);options=[];
sol=bvp4c(@ode,@bc,solinit,options);xint=linspace(xa,xb,100);S=deval(sol,xint);
function res=bc(ya,yb)
res=[ya(1); ya(2)-1; ya(4)-1; ya(6)-1; yb(2); yb(4); yb(6)];        
end 
function dydx=ode(x,y)    
dydx=[y(2);  y(3);  y(2)^2 - y(3)*y(1);    y(5);          - Pr*(y(1)*y(5) + Nb*y(5)*y(7) + Nt*y(5)^2);
           y(7);    - Le*y(7)*y(1) + (Nt/Nb)*Pr*(y(1)*y(5) + Nb*y(5)*y(7) + Nt*y(5)^2)];             
end
end
3 commentaires
  MINATI PATRA
 le 23 Mai 2020
				Dear Darova that M gives wrong code as you can compare and another question is how to include in bvp 4c code
Réponses (1)
  darova
      
      
 le 24 Mai 2020
        Try this
clc,clear
syms f(x) g(x) h(x) x Y
Pr=10;
Le=10;
Nt=.1;
Nb=.1;
[V,y1] = odeToVectorField( diff(f,3) - diff(f)^2 + f * diff(f,2) == 0,...
    diff(g,2) + Pr * ( f * diff(g) + Nb * diff(g)* diff(h)+ Nt * diff(g)^2) == 0,...
    diff(h,2) + Le * f * diff(h) + ( Nt/Nb ) * Pr * ( f * diff(g) + Nb * diff(g)* diff(h)+ Nt * diff(g)^2)== 0)
F = matlabFunction(V,'vars', [x Y]);
bc = @(ya,yb) [ya(1)    % g
    ya(2)-1 % Dg
    ya(4)-1 % f
    ya(6)-1 % Df
    yb(2)   % D2f
    yb(4)   % h
    yb(6)]; % dh
xa=0;
xb=6;
solinit = bvpinit(linspace(xa,xb,1000),[0 1 1 1 0 0 0]);
options = [];
sol = bvp4c(F,bc,solinit,options);
plot(sol.x,sol.y)
Change boundary conditions if needed
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