findBoundaryConditions

R2026b

Find boundary condition assignment for a geometric region

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Syntax

BCregion = findBoundaryConditions(BCs,RegionType=RegionID)

Description

BCregion = findBoundaryConditions(BCs,RegionType=RegionID) returns boundary condition BCregion assigned to the specified region.

example

Examples

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Open Live Script

Create a PDE model and import a simple block geometry. Plot the geometry displaying the face labels.

model = createpde(3);
importGeometry(model,"Block.stl");
pdegplot(model,FaceLabels="on",FaceAlpha=0.5)

Figure contains an axes object. The axes object contains 6 objects of type quiver, text, patch, line.

Set zero Dirichlet conditions on faces 1 and 2 for all equations.

applyBoundaryCondition(model,"dirichlet",Face=1:2,u=[0,0,0]);

On face 3, set the Neumann boundary condition for equation 1 and Dirichlet boundary condition for equations 2 and 3.

applyBoundaryCondition(model,"mixed",Face=3, ...
    h=[0 0 0;0 1 0;0 0 1], ...
    r=[0;3;3], ...
    g=[10;0;0], ...
    q=[1 0 0;0 0 0;0 0 0]);

Set Neumann boundary conditions with opposite signs on faces 5 and 6 for all equations.

applyBoundaryCondition(model,"neumann",Face=4:5,g=[1;1;1]);
applyBoundaryCondition(model,"neumann",Face=6,g=[-1;-1;-1]);

Check the boundary condition specification on face 1.

findBoundaryConditions(model.BoundaryConditions,Face=1)
ans = 
  BoundaryCondition with properties:

           BCType: 'dirichlet'
       RegionType: 'Face'
         RegionID: [1 2]
                r: []
                h: []
                g: []
                q: []
                u: [0 0 0]
    EquationIndex: []
       Vectorized: 'off'
       InternalBC: []

Check the boundary condition specification on face 3.

findBoundaryConditions(model.BoundaryConditions,Face=3)
ans = 
  BoundaryCondition with properties:

           BCType: 'mixed'
       RegionType: 'Face'
         RegionID: 3
                r: [3×1 double]
                h: [3×3 double]
                g: [3×1 double]
                q: [3×3 double]
                u: []
    EquationIndex: []
       Vectorized: 'off'
       InternalBC: []

Check the boundary condition specification on face 5.

findBoundaryConditions(model.BoundaryConditions,Face=5)
ans = 
  BoundaryCondition with properties:

           BCType: 'neumann'
       RegionType: 'Face'
         RegionID: [4 5]
                r: []
                h: []
                g: [3×1 double]
                q: []
                u: []
    EquationIndex: []
       Vectorized: 'off'
       InternalBC: []

Input Arguments

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Boundary conditions of a PDE model, specified as the BoundaryConditions property of PDEModel.

Example: model.BoundaryConditions

Geometric region type, specified as Face for 3-D geometry or Edge for 2-D geometry.

Example: findBoundaryConditions(model.BoundaryConditions,Face=3)

Data Types: char | string

Geometric region ID, specified as a vector of positive integers. Find the region IDs by using pdegplot with the FaceLabels (3-D) or EdgeLabels (2-D) value set to "on".

Example: findBoundaryConditions(model.BoundaryConditions,Face=3)

Data Types: double

Output Arguments

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Boundary condition for a particular region, returned as a BoundaryCondition object.

Version History

Introduced in R2016b

See Also

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