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Dear All,

i am solving a system of pde with boundar conditons then i got this error...

Error, (in pdsolve/numeric/plot) unable to compute solution for tau>HFloat(0.0):

Thank.

jeffrey_fluid.mw

restart

with(plots):

``

Pr := .71;

.71

 

1

 

1

 

1

(1)

PDE := {(diff(theta(eta, tau), eta, eta))/Pr+f(eta, tau)*(diff(theta(eta, tau), eta))-theta(eta, tau)*(diff(f(eta, tau), eta))-a*(diff(theta(eta, tau), tau)) = 0, diff(f(eta, tau), eta, eta, eta)+f(eta, tau)*(diff(f(eta, tau), eta, eta))-(diff(f(eta, tau), eta))^2-a*(diff(f(eta, tau), eta, tau))-K*(a*(diff(f(eta, tau), eta, eta, eta, tau))+2*(diff(f(eta, tau), eta))*(diff(f(eta, tau), eta, eta, eta))-(diff(f(eta, tau), eta, eta))^2-f(eta, tau)*(diff(f(eta, tau), eta, eta, eta, eta)))+lambda*(1+epsilon*cos(Pi*tau))*theta(eta, tau) = 0};

{1.408450704*(diff(diff(theta(eta, tau), eta), eta))+f(eta, tau)*(diff(theta(eta, tau), eta))-theta(eta, tau)*(diff(f(eta, tau), eta))-(diff(theta(eta, tau), tau)) = 0, diff(diff(diff(f(eta, tau), eta), eta), eta)+f(eta, tau)*(diff(diff(f(eta, tau), eta), eta))-(diff(f(eta, tau), eta))^2-(diff(diff(f(eta, tau), eta), tau))-K*(diff(diff(diff(diff(f(eta, tau), eta), eta), eta), tau)+2*(diff(f(eta, tau), eta))*(diff(diff(diff(f(eta, tau), eta), eta), eta))-(diff(diff(f(eta, tau), eta), eta))^2-f(eta, tau)*(diff(diff(diff(diff(f(eta, tau), eta), eta), eta), eta)))+(1+cos(Pi*tau))*theta(eta, tau) = 0}

(2)

IBC := {f(0, tau) = 0, f(10, tau) = 0, f(eta, 0) = 0, theta(0, tau) = 1, theta(10, tau) = 0, theta(eta, 0) = 0, (D[1](f))(0, tau) = 1, (D[1](f))(10, tau) = 0};

{f(0, tau) = 0, f(10, tau) = 0, f(eta, 0) = 0, theta(0, tau) = 1, theta(10, tau) = 0, theta(eta, 0) = 0, (D[1](f))(0, tau) = 1, (D[1](f))(10, tau) = 0}

(3)

L := [1]

[1]

(4)

for i to 1 do K := L[i]; pds := pdsolve(PDE, IBC, numeric, spacestep = 1/100); p[i] := plots[display]([seq(pds:-plot(f, tau = 1, eta = 0 .. 1, legend = L[i]), j = 5)]) end do

1

 

module () local INFO; export plot, plot3d, animate, value, settings; option `Copyright (c) 2001 by Waterloo Maple Inc. All rights reserved.`; end module

 

Error, (in pdsolve/numeric/plot) unable to compute solution for tau>HFloat(0.0):
Newton iteration is not converging

 

display({p[1]})

Error, (in plots:-display) expecting plot structures but received: {p[1]}

 

``

 

Download jeffrey_fluid.mw

test.mw

In this file, I tried my best to solve the pde. But the answer is still rather non-informative. I need some help to simplify it.

I did notice that my Maple might need reinstallation, due to a "bug" in the 18.02 update.

 

My ultimate aim is try to use some similar techniques to solve this, test2.mw, which has a similar type pde.

 

The standard pdsolve(pde) would just not work.

 

UPDATE:

I used the same file in Maple 17 on a differnt Machine, which can be solved by pdsolve. So I guess it's just that  the 18.02 update package is broken itself. I have tried to uninstall and reinstall twice.

 

 

Thanks,

 

casper

PD := [diff(Th(z, t), t) = 7.1428*(diff(Th(z, t), z))-1397941.885*(279-Tw(z, t))-0.2160487e-1*(diff(Th(z, t), z, z)), diff(Tc(z, t), t) = -7.1428*(diff(Tc(z, t), z))+1298990.852*(Tw(z, t)-291)+0.189366e-1*(diff(Tc(z, t), z, z)), diff(Tw(z, t), t) = 3.3024901*(Th(z, t)-2*Tw(z, t)+Tc(z, t))+8.0029*10^(-4)*(diff(Tw(z, t), z, z))]

BCI := {Tc(0, t) = 275, Tc(z, 0) = 275, Th(1, t) = 296, Th(z, 0) = 296, Tw(0, t) = 0, Tw(z, 0) = 0, (D[1](Tc))(1, t) = 0, (D[1](Th))(0, t) = 0, (D[1](Tw))(1, t) = 0}

pds := pdsolve(PD, BCI, numeric)

Hello,

Since I was working in Matlab with Galerkin method which implies periodic boundary conditions I was wondering how to implement this in maple.

I tried this:

restart;

pde2 := diff(u(x, t), t)+3*(diff(u(x, t)^2, x))+diff(u(x, t),x$3) = 0

IBC := {u(0, t) = u(2, t), u(x, 0) = sech(50*(x-1/2))^2+2*sech(30*(x-1))^2, (D[1](u))(0, t) = (D[1](u))(2, t), (D[2](u))(0, t) = (D[2](u))(2, t)}

pds := pdsolve(pde2, IBC, numeric, time = t, range = 0 .. 2)

But it's telling me: 

Error, (in pdsolve/numeric/process_IBCs) initial/boundary conditions can only contain derivatives which are normal to the boundary, got (D[2](u))(0, t)

So what's wrong?

declare(W(x, y), Z(x, y));

 

sys := [-A*kappa3-`∂`(`∂`(W(x, y))/`∂`(x))*(2*G-A)/`∂`(x)-2*G*(`∂`(`∂`(W(x, y))/`∂`(y))/`∂`(y)+`∂`(`∂`(Z(x, y))/`∂`(x))/`∂`(y))+A*`∂`(`∂`(Z(x, y))/`∂`(x))/`∂`(y) = 0, `∂`(`∂`(Z(x, y))/`∂`(y))*(A-4*G)/`∂`(y)+`∂`(`∂`(W(x, y))/`∂`(x))*(A-2*G)/`∂`(y)-2*G*`∂`(`∂`(Z(x, y))/`∂`(x))/`∂`(x) = 0];

 

I have this system of coupled PDE and I wish to solve it using Maple.

It gives me error of this kind:

 

pdsolve(sys, [[W(x, y)], [Z(x, y)]]);


Error, (in pdsolve/sys) found functions depending on different variables in the given DE system: [`∂`(x), `∂`(y)]

 

Thanks a lot for help

I'm taking my first steps with maple and pdsolve, trying to run the example in the maplesoft support page:

http://www.maplesoft.com/support/help/Maple/view.aspx?path=examples/pdsolve_boundaryconditions

which reads

>
> restart; with(PDEtools);
> U := diff_table(u(x, t));
>

and I get a solution that is different from the web page, and when i run

Im using maple 13. Any tips about what's wrong?

 

regards

restart:with(plots):with(PDEtools):

 pde:=1/r*diff(r*diff(U(r,z),r),r)+1/b^2*diff(U(r,z),z,z)=0;

ans := pdsolve(pde);

ics:=(D[1](U))(0, z) = 0,(D[2](U))(r, 0)-B*U(r,0) = 0;

bcs:=(D[2](U))(r, 1)+B*U(r,1) = B,(D[1](U))(1, z)+B*U(1,z) = 0;

B:=1:b:=1:

S:= pdsolve(pde, {bcs, ics}, numeric);

Error, (in pdsolve/numeric) unable to handle elliptic PDEs

anyway around this?

 

RIZPDE.mw

Dear all,

I tried to use pdsolve to solve the parabolic pde but get the unexpected answer:

Is it the PDESolStruc or the other structure? Where can I find the description about this kind of structure.

Thanks.

Hello everyone,

i'm trying to simulate a diffusion problem. It contains two connected regions in which a species is diffusing at different speeds. In one region (zeta) one boundary is set to be constant whereas in the other region (c) there is some oscillation at the boundary.The code i try to use is as follows:

sys1 := [diff(c(x, t), t) = gDiffusion*10^5*diff(c(x, t), x$2), diff(zeta(x, t), t) = KDiffusion*10^6*diff(zeta(x, t), x$2)]

pds := pdsolve(sys1, IBC, numeric, time = t, range = 0 .. 3000, spacestep = 3)

However the main problem are my boundary conditions:

IBC := {c(0, t) = 0, c(x > 0, 0) = 0, zeta(0, t) = .4, zeta(x > 0, 0) = .4, (D[1](c))(3000, t) = sin((1/100)*t), (D[1](zeta))(0, t) = 0}

Like this it principally works (however it is apparently ill-posed).

Now what i do like is that the two equations are coupled at x=2000 with the condition that c(2000,t)=zeta(2000,t). This however i dont seem to be able to implement.

I appreciate your comments

Goon

why system inconsistent 

when only want to obtain a equation H

in terms of a1 , a3, b2, b3, c1, c2, x1, x2, lambda

pdsolve([
Diff(H(x1,x2,lambda), x1) = a1*x1 + a3*lambda,
Diff(H(x1,x2,lambda), x2) = b2*x2 + b3*lambda,
Diff(H(x1,x2,lambda), lambda) = c1*x1 + c2*x2
], H(x1,x2,lambda));

Hi! 

When trying to find the fundamental solution of the Heat equation using Maple (software), I get the following Error message which seems to have no documentation available (?) :

Using :

          PDE := -(diff(f(x, t), t))+(diff(f(x, t), x, x))*Di = 0

assume(epsilon > 0);

pdsys := [PDE, f(x, 0) = Dirac(x-epsilon)];

pdsolve(pdsys, build)

"Error, (in casesplit/K) this version of casesplit is not yet handling the function: Dirac"

Anybody has an idea what that is? (Using Maple 17) . How can I solve this problem ? 

 

http://en.wikipedia.org/wiki/Heat_equation

 

Thanking you on Advance, 

Erez . 

Hi,

I need your help to fix the error in this code.  many thinks
restart:
pde:=diff(u(t,x),t$2)=diff(u(t,x),x$2)-sin(u(t,x)):
f:=x->x^2:
IBC := {u(0,x)=f(x),u(t,-50)=0,D[2](u)(t, 50)=0,D[1](u)(0, x)=-diff(f(x),x)}:

pds := pdsolve(pde, IBC, numeric):

p1 := pds:-plot(t = 0);
p2 := pds:-plot(t = 1/10);
p3 := pds:-plot(t = 1/2);
p4 := pds:-plot(t = 1);
p5 := pds:-plot(t = 2);
plots[display]({p1, p2, p3, p4, p5}, title = `Sine Gordaon at t=0,0.1,0.5,1,2`);

Hi,

I try to solve this equation using pdsolve but there is no results.
restart:
with(PDEtools):
with(plots):

Eq:=diff(u(t,x), t$2) =diff(u(t,x),x$2)+sin(u(t,x));

pdsolve(Eq);

Thank you for your help.

 

I'm trying to analytically solve for a Laplace's equation in a unit square with the following BCs: u(x,0) = 0, u(y,0) = 0, u(1,y) = 0, u(x,1) = 1

The series solution to this problem is well-known, where u(x,y) is solved with separation of variables to obtain u in terms of sin and sinh series.

I try to recreate the solution with pdsolve but am stuck with it.

My attempt:

 

lap2d := diff(u(x,y), x, x) + diff(u(x,y), y, y) = 0

sol := pdsolve(lap2d, HINT = X(x)*Y(y), build)  % saw this in mapleprimes

With this I managed to get an expression for u(x,y). My trouble is with the coefficients: _C1, _C2, _C3, _C4, _c_1

_C1 .. _C4 are clearly from integrations, but I am not clear about _c_1?

To solve for the constants of integrations, I tried to set up simultaneuous equations with the BCs.

For example,

eq1 := eval( rhs(sol), x=0) = 0

Similarly, repeat for the other 3 BCs to get eq2, eq3, eq4

I tried to solve these simultaneous eqns with:

solve({eq1, eq2, eq3, eq4}, {_C1, _C2, _C3, _C4})

but Maple does not output anyting.

Need your advice if this is the right way and I just goofed up with the syntax, or there are better ways to construct the series solution of the problem. Should I use linearsolve to find the C's?

I use Maple 17.

 

Thanks in advance

 

 

Hi, everyone!

I need help.

There are a system of 2 pde's: 

diff(Y(x, t), x$2) = exp(-2*x*b)*(A(x, t)-Y(x, t)), diff(A(x, t), t) = exp(-2*x*b)*(Y(x, t)-A(x, t)) 

and initial and boundary conditions: 

A(x, 0) = 0, Y(0, t) = 0.1, (D[1](Y))(0, t) = 0. 

Goal: 
For each b = 0, 0.05, 0.1. 
1)to plot 3-d  Y(x,t): 0<=x<=20,0<=t<=7. 
2)to plot  Y(x,4). 

Are there any methods with no finite-difference mesh?


I realized the  methods such as  pds1 := pdsolve(sys, ibc, numeric, time = t, range = 0 .. 7)  can't help me:

Error, (in pdsolve/numeric/match_PDEs_BCs) cannot handle systems with multiple PDE describing the time dependence of the same dependent variable, or having no time dependence 

I found something, that can solve my system analytically: 
pds := pdsolve(sys), where sys - my system without initial and boundary conditions. At the end of the output: huge monster, consisted of symbols and numbers :) And I couldn't affiliate init-bound conditions to it.

I use Maple 13. 

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