Answered

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...

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...

16 days ago | 2

| accepted

Answered

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...

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...

28 days ago | 0

| accepted

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...

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...

3 months 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 ...

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 ...

4 months 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...

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...

4 months 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]' ;

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]' ;

4 months 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...

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...

4 months 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...

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...

5 months 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...

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...

6 months 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...

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...

6 months 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...

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...

6 months 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,...

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,...

7 months 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...

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...

7 months 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...

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...

7 months 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; ...

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; ...

7 months 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...

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...

9 months 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...

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...

1 year 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 ...

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 ...

1 year 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...

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...

1 year 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 ...

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 ...

1 year ago | 1

| accepted

Answered

Euler-Bernoulli's beam ODE or PDE

Take a look at this example: beam dynamics with pdepe

Euler-Bernoulli's beam ODE or PDE

Take a look at this example: beam dynamics with pdepe

2 years 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...

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...

2 years 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...

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...

2 years 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...

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...

2 years 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...

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...

2 years 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:...

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:...

2 years 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...

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...

2 years 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...

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...

2 years 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...

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...

3 years 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...

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...

3 years ago | 0

| accepted