can't run applyBoundaryCondition

I'm trying to run the following code to solve 3D PDE on a unit cube usind pdetool functions. I've got two error messeges

1- Error using pde.ThermalMaterialAssignment/checkThermalConductivitySize

Incorrect ThermalConductivity size.

2- Unrecognized function or variable 'applyBoundaryCondition'.

% 1. Define the Geometry of the Unit Cube
model = createpde('thermal', 'steadystate');
L = 1; % Length of the unit cube
gm = multicuboid(L, L, L); % Create a unit cube geometry
model.Geometry = gm;
pdegplot(model,"FaceLabels","on","FaceAlpha",0.5)

% 2. Define the Anisotropic Poisson Equation
% Define anisotropic conductivity matrix (3x3 tensor)
K = [2 1 0; 1 3 0; 0 0 1]; % Example anisotropic conductivity tensor

% Define the source term f(x, y, z)
f = @(location, state) 1; % Constant source term for simplicity

% Set thermal properties for the Poisson equation
thermalProperties(model, 'ThermalConductivity', K);

% Solver options
model.SolverOptions.RelativeTolerance = 1e-6;
model.SolverOptions.AbsoluteTolerance = 1e-6;

% 3. Apply Boundary Conditions (Dirichlet u = 0 on all boundaries)
% 3. Apply Boundary Conditions (Dirichlet u = 0 on all boundaries)
applyBoundaryCondition(model,"dirichlet", ...
                             "Face",1:6,"u",0);

Unrecognized function or variable 'applyBoundaryCondition'.

% 4. Mesh the Geometry
generateMesh(model, 'Hmax', 0.1); % Adjust Hmax for finer or coarser mesh

% 5. Solve the Poisson Equation
result = solve(model);

% 6. Postprocessing and Visualization
u = result.NodalSolution
figure
pdeplot3D(model, 'ColorMapData', u);
title('Solution to the 3D Anisotropic Poisson Equation');
xlabel('X');
ylabel('Y');
zlabel('Z');
colorbar;

Answer 1

[Torsten]

"applyBoundaryConditions" is used for general PDE models. You want to use the "thermal" model.

The available properties and object functions are listed here:

https://uk.mathworks.com/help/pde/ug/pde.thermalmodel.html

I think the keyword is "thermalBC" in this case.