can it be possible to use odeVectorField

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MINATI
MINATI on 22 May 2020
Commented: MINATI on 25 May 2020
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 Comments
MINATI PATRA
MINATI PATRA on 23 May 2020
Dear Darova that M gives wrong code as you can compare and another question is how to include in bvp 4c code
MINATI
MINATI on 24 May 2020
Please anybody invest some time here to help me.

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Answers (1)

darova
darova on 24 May 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
  1 Comment
MINATI
MINATI on 25 May 2020
No dear Darova, its not matching. You can compare also

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