# Items tagged with pdepde Tagged Items Feed

23 hours ago
0 0

### Error, (in pdsolve/numeric/process_PDEs) can only ...

Yesterday at 1:15 AM
0 7

hi .may every one help me for pdsolve this differential equations?

all initial boundary condition are zero

thanks...

pdeSol_(1).mw

 > # # Define some parameters #   sigma := 10; N := 0; beta := 1; alpha := 1; PDE1 := diff(w(X, theta, t), X, X, X, X)+2*alpha^2*(diff(w(X, theta, t), theta, theta, X, X))+alpha^4*(diff(w(X, theta, t), theta, theta, theta, theta))-N*(diff(w(X, theta, t), X, X))+diff(w(X, theta, t), t, t)-beta*w(X, theta, t)-sigma = 0
 (1)
 > # # Define the PDES #   PDEs:= { diff(w(X, theta, t), X, X, X, X)+2*alpha^2*(diff(w(X, theta, t), theta, theta, X, X))+alpha^4*(diff(w(X, theta, t), theta, theta, theta, theta))-N*(diff(w(X, theta, t), X, X))+diff(w(X, theta, t), t, t)-beta*w(X, theta, t)-sigma = 0    };
 (2)
 > # # Set of boundary conditions at x=1. #    bcs1:= { D[1](w)(1,theta, t) = 0,               w(1,theta, t) = 0          };
 (3)
 > # # Set of boundary conditions at x=0 #   bcs2:= {    w(0,theta, t)=0,            D[1](w)(0,theta, t)=0          };
 (4)
 > # # Set of boundary conditions at t=0 #   bcs3:= { w(x,theta,0)=0,                       D[2](w)(x,theta,0)=0 };
 (5)
 >
 > pdsolve( PDEs, union(bcs1, bcs2, bcs3), numeric);
 >

### Nonlinear Coupled PDE...

August 17 2016
1 4

Hy Prof.

pde[1] := diff(u(x, t), t)-D(diff(u(x, t), x, x)) = alpha*u(x, t)*(1-v(x, t))

pde[2] := diff(v(x, t), t)-E(diff(v(x, t), x, x)) = beta*v(x, t)*(1-u(x, t))

### Problem with PDE...

August 12 2016
0 3

i have 2 PDE equations with some boundary conditions,maple get me errors, what should i do ? please help
how can i make correction in my system or boundary to have a solution ?

### How to convert PDE to ODE using Lie group...

July 28 2016
1 1

Can some one help me for converting three or two coupled pdes to odes using Lie group or any other method in maple

### Symmetries of strange PDE...

June 29 2016
2 11

I thought about the following PDE:

EDIT: The u(0,t) is not a typo! It is really meant to be part of the PDE!

Latex/Matjax: $$\dfrac{\partial u(x,t)}{\partial t}=\alpha \dfrac{\partial^2 u(x,t)}{\partial x^2}+u(x=0,t).$$

Maple: diff(u(x,t),t)=alpha*diff(u(x,t),x$2)+u(0,t) How can i determine the symmetries of this PDE with Maple? ### How to write boundary condition in pdsolve?... June 21 2016 1 4 I have the PDE u_{xx}+u_{yy} = 1 with BC: u|_{x^2+y^2=1} =0 ; how to write down the command of the BC in solving this PDE?, btw can I make maple show me how to solve this PDE analytically? Thanks in advance. Here are the lines that I wrote so far: pde := diff(u(x, y), x, x)+diff(u(x, y), y, y) = 1; ans := pdsolve(pde) how to add the BC correctly to pdsolve? I am not sure how to write the condition x^2+y^2=1 and that u will get a value on this boundary. ### Solve PDE by Maple... June 20 2016 0 6 Hi all, Please help me with this question. I want to solve a PDE by Maple.  (1)  (2)  (3)  (4) ### How to solve this PDE system?... June 19 2016 0 6 hi .please help me for solve this equations. bbb2.mw  (1)  (2)  (3)  (4)  (5) if former equations are not solvable , please help me for another way, in which at first two equation solve..in this way in equation [J and B] assume that q[311]=e[311]=0 and dsolve perform to find Φ and ψ after by finding Φ and ψ is use for detemine w and u0 please see attached file below[bbb2_2.mw] bbb2_2.mw Download bbb2.mw ### Problem with PDE solution ... June 08 2016 1 8 vz := 2*(-eta^2+1); D_im := .22; r0 := 1; pde := diff(vz*Y(eta, z), z)-D_im*((diff(eta*(diff(Y(eta, z), eta)), eta))/eta+diff(Y(eta, z), $(z, 2)))/r0 = 0;

pde := expand(%);

ibc := [Y(1, z) = 0, (D[1](Y))(0, z) = 0, Y(eta, 0) = 1, (D[2](Y))(eta, 0) = 0];

sol := pdsolve(pde, ibc, numeric, time = z, range = 0 .. 1);

pds := sol:-value(z = 0, output = listprocedure);

sol:-plot(z = 0.1e-3, numpoints = 50, color = blue, view = 0 .. 1)

So I was trying to solve this conservation equation for the radial coordinate eta and the z coordinate being treated as time. The flow is in z direction. Now unfortunately it is diverging. Not sure why though. What am I doing wrong?

### How to solve this PDE problem?...

May 22 2016
0 5

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hai All,

i have problem to soilve pde in the maple

can anyone suggest / idea to solve in maple?

### PDE system ...

May 07 2016
0 3

I am currently working on FDM ,i have 2 coupled nonlinear pde ,i need help in solving these equation using maple code.

> restart:

> alias(f=f(tau,eta), theta=theta(tau,eta));

>

> PDE1:=S*diff(f,tau,eta)=eta^2*diff(f,eta)^2+(6*eta^2-2*f*eta)*diff(f,eta)+(6*eta^3-f*eta)*diff(f,eta,eta)-eta^4*diff(f,eta,eta,eta);

> PDE2:=eta^4*diff(theta,eta,eta)+2*eta^3*diff(theta,eta)-Pr*(f*eta^2*diff(theta,eta)+S*diff(theta,tau))=0;

### Error when using pdsolve...

May 04 2016
1 7

I'm trying to solve a 2nd order system of pde's with couplded BC but it gives me the following error

Error, (in pdsolve/numeric) initial/boundary conditions must be defined at one or two points for each independent variable

Here is the code

> T01 := 273; T02 := 26; L1 := .1; L2 := .2; h1 := 100; h2 := 200; k1 := 1; k2 := 2; rho1 := 1000; rho2 := 2000; c1 := 0.1e6; c2 := 0.2e6; alpha1 := 1; alpha2 := 2

> PDE := {diff(T1(x, t), t) = (diff(T1(x, t), x, x))/alpha1, diff(T2(x, t), t) = (diff(T2(x, t), x, x))/alpha2}

> IBC:={k1*(D[1](T1))(L1, t) = k2*(D[1](T2))(L1, t), T1(L1, t) = T2(L1, t), T1(x, 0) = T02, T2(x, 0) = T02, (D[1](T1))(0, t) = -h1*(T1(0, t)-T01)/k1, (D[1](T2))(L1+L2, t) = h2*(T2(L1+L2, t)-T02)/k2}

> pds := pdsolve(PDE, IBC, numeric)

Its basically a 1D heat equation in a 2 layers plate with conduction BC on both sides

### How to solve a nonlinear PDE system?...

April 16 2016
0 3

I am currently working on FDM ,i have 2 coupled nonlinear pde ,i need help in solving these equation using maple code.

> restart:

> alias(f=f(tau,eta), theta=theta(tau,eta));

>

> PDE1:=S*diff(f,tau,eta)=eta^2*diff(f,eta)^2+(6*eta^2-2*f*eta)*diff(f,eta)+(6*eta^3-f*eta)*diff(f,eta,eta)-eta^4*diff(f,eta,eta,eta);

> PDE2:=eta^4*diff(theta,eta,eta)+2*eta^3*diff(theta,eta)-Pr*(f*eta^2*diff(theta,eta)+S*diff(theta,tau))=0;

### Modelling solitons...

March 29 2016
1 6

Hi guys, I'm currently having a lot of trouble with Maple and can't seem to get stuff to work. I have the task of solving and modelling the Klien Gordon equation, with a chosen potential. The equation I'm trying to solve is:

> KGE := diff(psi(x, t), x, x)-(diff(psi(x, t), t, t))-12*psi(x, t)^5+10*psi(x, t)^4+6*psi(x, t)^3-3*psi(x, t)^2-psi(x, t) = 0

I'm doing this by changing the pde into an ode via a transformation

>tr := {t = tau, x = c*tau+z, psi(x, t) = U(z)}

>ode1 := dchange(tr, KGE, [z, tau, U(z)])

>ode1 := collect(ode1, diff(U(z), z, z))

>c := 1/4

>ode2 := subs({U(z) = U, diff(U(z), z, z) = V(U)*(diff(V(U), U))}, ode1)

>sol := dsolve({ode2, V(0) = 0}, V(U))

>sol1:= sol[2]

>z := -c*t+x = int(1/rhs(sol2), U)

>solwave := psi(x, t) = solve(z, U)

I then checked if my solution, solwave actually solved the pde via pdetest(solwave,KGE) and it did. Hence this is what I took as one of the kinks. Although the kink solution looks hideous and I have no idea how to try and take the limit as x goes to infinity, as to show it tends to a vacuum of the potential. I've tried taking the limit but all Maple does is replace all the x with infinity signs...

I then tried animating it to see if it worked, but it just looks wrong, there are breaks within the curve and also very random spikes which I cannot explain at all..

I tried this code exactly for the Sine Gordon equation and it works perfectly, it just all goes wrong when I try to change the potential.

Here is a picture of the frame:

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Another issue I had was with dealing with the potential on it's own, every time I try inputting

>1/2(u^2)(1-u)^2(1+2u)^2

into maple it changes the expression into something completely different and wrong, it somehow comes out with an exponential of 8.. This is what I get:

(1/2)*(u(1-u))(1+2*u)^8

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I also have a problem integrating, I try and plug in a value, i.e.

>int(1/(x(1-x))(1+2*x), x)

but all this does is show me what I inputted but with a integral sign...

I'm very very new to Maple and have spent over a week doing this, but it just isn't working out at all :( Please help!!

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