Community Profile

photo

Bill Greene


Last seen: 1 dag ago
52 total contributions since 2014

Contact

Bill Greene's Badges

  • Knowledgeable Level 3
  • 3 Month Streak
  • Revival Level 1
  • First Answer

View details...

Contributions in
View by

Answered
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...

28 dagen ago | 1

| accepted

Answered
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 ...

29 dagen ago | 0

| accepted

Answered
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...

ongeveer een maand ago | 0

| accepted

Answered
Gas-Solid Reaction Modeling with Random Pore Model. Pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.
Your right-end boundary conditions are invalid. Possibly you want: pr=[ur(1)-1 0]'; qr =[0 1]' ;

ongeveer 2 maanden ago | 1

| accepted

Answered
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...

ongeveer 2 maanden ago | 0

Answered
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...

ongeveer 2 maanden ago | 0

| accepted

Answered
Problem about mixture of ode-pde
I have developed a PDE solver, pde1dM, that Ibelieve can solve your coupled PDE/ODE system. The solver runs in MATLAB and is s...

3 maanden ago | 1

| accepted

Answered
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...

4 maanden ago | 0

| accepted

Answered
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...

4 maanden ago | 0

Answered
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,...

4 maanden ago | 1

| accepted

Answered
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...

4 maanden ago | 0

| accepted

Answered
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...

4 maanden ago | 0

| accepted

Answered
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; ...

5 maanden ago | 0

Answered
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...

6 maanden ago | 0

Answered
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...

11 maanden ago | 0

| accepted

Answered
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 ...

12 maanden ago | 0

| accepted

Answered
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...

ongeveer een jaar ago | 0

Answered
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 ...

ongeveer een jaar ago | 1

| accepted

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

meer dan een jaar ago | 0

| accepted

Answered
Solving advection diffusion pde
The only problem I see with your code is in the boundary conditions. I corrected your bcfun function and have attached my versio...

bijna 2 jaar ago | 1

Answered
Moving boundary problem with Stefan condition (modeling mass and heat transfer for sublimation front)
I think you may be able to solve this problem using the |pdepe| function. The idea is that you model both phases as a single re...

ongeveer 2 jaar ago | 0

Answered
Error using pdepe - Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.
The fundamental cause of your problem is that your initial conditions are inconsistent with your boundary condition at |x=0|. M...

meer dan 2 jaar ago | 0

| accepted

Answered
How to rewrite a PDE equation and set the parameters for solving the temperature changes?
I think you can use |pdepe| to solve this but you need to include both the equation for Ts and the one for Tg; in your pde funct...

meer dan 2 jaar ago | 0

Answered
How do I solve fourth order PDE numerically?
I have created an example, which might be of help, showing how to use the |pdepe| function to solve the beam equation : <https:...

meer dan 2 jaar ago | 1

| accepted

Answered
How to speed up LU decomposition in ode15s solver?
You didn't provide any details of exactly how you are using |ode15s| but I suspect you can substantially improve the performance...

meer dan 2 jaar ago | 0

| accepted

Answered
what is wrong in my pdepe code ?
The problem you have described is ill-posed. The source term must be prescribed over some finite length of the domain, not simp...

meer dan 2 jaar ago | 0

Answered
Error in using MATLAB PDEPE function - incorrect matrix sizing
The line f = [DuDx-Pe.*u(1); 0]; is creating a variable |f| with three rows rather than the correct two rows because |Du...

meer dan 2 jaar ago | 0

Answered
Implicit formulation of finite difference with ode15s
I am still unclear on many aspects of your problem. And I am unable to access the paper you reference so that is of no help to...

meer dan 2 jaar ago | 0

| accepted

Answered
issue with pdepe: "Spatial discretization has failed."
Beyond the problems already mentioned by Torsten, the reason for the error message is that you have listed the returned argumen...

meer dan 2 jaar ago | 0

Answered
Step Function as Input Boundary Condition to MATLAB PDEPE solver
I suggest you smooth the sharp corners in your boundary condition profile using a Heaviside function similar to the code below. ...

meer dan 2 jaar ago | 1

| accepted

Load more