How can I resolve the error "PDE coefficients cannot be function of solution or time." in a static solution of a PDE.

Hi

I am trying to solve a general PDE system with size 2. I have 2 set of dispalcement data at boundaries (shown as Disdata in code ) of model, which have been interpolated using interp1 function. The displacement function obtained from interpolation is employed as a boundary condition function to the model. While I am solvoing this problem using command

FEM = assembleFEMatrices(model,'nullspace') ;

I am getting a error "PDE coefficients cannot be function of solution or time" for 1 set data of dispacement but I am getting results for 2 set of data.

As I am solving a static linear problemsolving , why am I getting this error?

This a one portion of my code.

% specify PDE cofficient

specifyCoefficients(model,'m',0,'d',0,...

'c',[C11, 0 , 0 ,G,0 ,C12,G,0 ,0 ,G,C12,0 ,G,0 ,0 ,C11]',...

'a',[0; 0; 0; 0 ],'f',[ 0; 0 ]);

% Call displcement interpolation function

[UVdispB, UVdispT, UVdispL, UVdispR]=InterpolateDisplacement(Disdata);

%Apply a displcement on respective boundary Edges in x and y-directions

applyBoundaryCondition(model,'dirichlet','Edge',EdgeB,'u',@UVdispB,'Vectorized','on');

applyBoundaryCondition(model,'dirichlet','Edge',EdgeT,'u',@UVdispT,'Vectorized','on');

applyBoundaryCondition(model,'dirichlet','Edge',EdgeL,'u',@UVdispL,'Vectorized','on');

applyBoundaryCondition(model,'dirichlet','Edge',EdgeR,'u',@UVdispR,'Vectorized','on');

% Generate Mesh and Solve

meshsize=0.02*Lx;

grad=1.5;

generateMesh(model,'Hgrad',grad,'Hmax',meshsize,'GeometricOrder','quadratic');

%Plot the mesh.

figure (7)

pdemesh(model.Mesh.Nodes,model.Mesh.Elements);

%Assemble finite element matrices

FEM = assembleFEMatrices(model,'nullspace') ;

model.SolverOptions.ReportStatistics='on';

Answer 1

[Ravi Kumar]

What are the output arguments in you function call InterpolateDisplacement?

[UVdispB, UVdispT, UVdispL, UVdispR]=InterpolateDisplacement(Disdata);

Since you input them as applyBoundaryCondition(model,'dirichlet','Edge',EdgeB,'u',@UVdispB,'Vectorized','on'); etc, it might be telling the solvet that boundary conditions are nonlinear, that is, they depenend on the solution itself.

Regards,

Ravi

[Puneet Kumar]

Actually I was having dispalcement vectors at the boundaries, so I tried to interpolate using

UVdispB= @(z) interp1(x,Ub,z,'linear');

Ub is dispalcement vector at boundary and x is samples points. But I don't know that these functions are linear or nonlinear.