Community Profile Bill Greene

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Why does pdepe throw an error depending on boundary condition parameters?
Interesting. The ODE solver(ode15s) is numerically approximating the iteration matrix for the PDE and, due to roundoff er...

14 hours ago | 0

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How to deal these type of errors from pdepe? "Error in pdepe/pdeodes (line 359)"
Yes, in my example, the M-matrix was constant but the same idea applies if M is a function of x or the dependent variables. The ...

2 months ago | 0

How to deal these type of errors from pdepe? "Error in pdepe/pdeodes (line 359)"
pdepe does not accept a non-diagonal mass matrix. But often you can deal with this by calculating the inverse of the mass matrix...

2 months ago | 0

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Why does solving the heat equation with MATLAB (pdepe) yield a completely different result than the Heisler chart (analytical solution)?
I referred to section 5.5 of Bergman (the source of your pdf file) and wrote a function that computes the solution the Heisler c...

3 months ago | 0

Submitted

pde1dM
pde1dm is a 1D PDE solver that supports high order interpolation functions, coupled ODE and is compatible with pdepe input synta...

PDEPE: Unable to meet integration tolerances without reducing the step size below the smallest value allowed
I have occasionally seen similar problems with pdepe in the past. I have written a PDE solver that has input similar to pdepe...

10 months ago | 0

Solving a system a coupled ODE and PDE
The error message is caused by your definition of the ode function: function [dydt] = ode_syst2(t, Tg, Ts, Fig, Fis) The defin...

11 months ago | 0

Appropriate method for solving coupled pdes
Yes, although it is true that the documentation for pdepe describes it as a solver for parabolic systems, it can often obtain...

1 year ago | 2

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Solving PDEs with mass conservation
I don't know how to integrate the dependent variables using pdepe. However, I have written a PDE solver with an input syntax sim...

1 year ago | 0

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Pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.
The boundary conditions for your second PDE are invalid. These should work: pl = [0; 0]; ql = [1; 1]; pr = [ur(1)-cAO; 0]; q...

1 year ago | 1

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A system of PDEs which have one PDE with a spatial variable fixed term, u(x0, t)
pdepe is not really designed to handle systems of coupled PDE and ODE. However, I have written a PDE solver for MATLAB that has ...

1 year ago | 0

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Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.
Your boundary conditions for u2 (q=0, p=0 at each end) are not valid. The second equation in your system (u2_t=...) is, in fact...

1 year ago | 0

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How to define a step function as input BC in pdepe?
Here is the way you want to define such a BC: if(t>=50) pl = [ul(1);0]; else pl = [ul(1)-10;0]; end One thing you ha...

1 year ago | 0

PDE with time-dependent boundary conditions
I do not believe it is possible to solve this problem with pdepe. However I have written a one-dimensional PDE solver which i...

1 year ago | 0

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I have developed a PDE solver, pde1dM, that Ibelieve can solve your coupled PDE/ODE system. The solver runs in MATLAB and is s...

1 year ago | 1

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Solve heat equation with source term
T and m are referred to as dependent variables, not independent; x and t are the independent variables. This Example shows how t...

1 year ago | 0

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Unable to meet integration tolerances
Your equations have a fundamental error. Just calculate the "s" term along the length at the initial temperature and the problem...

1 year ago | 0

How to solve PDE problem
Your PDE can replaced by these two PDE which is a form acceptable to pdepe. However, pdepe, or in fact any numerical method,...

1 year ago | 1

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Solving second order PDE
The reason that pdepe imposes a boundary condition of the flux equal zero at the center is that this is required for the proble...

1 year ago | 0

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PDEPE: Unable to meet integration tolerances without reducing the step size below the smallest value allowed at time t.
You are trying to solve a system of ODE which is something pdepe is not designed for. Specifically, the pdepe documentation says...

1 year ago | 0

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1D Fourier equation with temperature dependent thermal properties
function [c,f,s] = pdex1pde(x,t,T,dudx,diffr,Tfront) diffr=3.34E-10*T^4 - 9.37E-07*T^3 + 9.38E-04*T^2 - 4.80E-01*T + 2.09E+02; ...

1 year ago | 0

how can I code a system of 2 pdes and an ode for modelling a packed bed
I did some experimentation with your code. Here are a couple of comments related to the changes I made: Because the equations a...

1 year ago | 0

PDE system - pdepe system example - error or incomplete description on Matlab website?
Looks like you have found an error in this documentation page. If you look at equation 3 in the referenced paper you will see th...

2 years ago | 0

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Pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.
Your boundary conditions (BC) are specified incorrectly; a qr(i) value of zero and pr(i)=constant is not a valid BC. Since you ...

2 years ago | 0

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PDEPE: Unable to meet integration tolerances for large values of Ra
The convergence problem you are seeing is due to the strong boundary layer effect near , i.e. the solution is undergoing a shar...

2 years ago | 0

How to define stepchanges, variable BC for different timeintervalls using pdepe?
The reason that your code didn't show a change in the BC with time is due to the programming error that Torsten pointed out. If ...

2 years ago | 1

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Euler-Bernoulli's beam ODE or PDE
Take a look at this example: beam dynamics with pdepe

3 years ago | 0

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