findBoundaryConditions

Find boundary condition assignment for a geometric region

Syntax

BCregion = findBoundaryConditions(BCs,RegionType,RegionID)

Description

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

Examples

Find Boundary Conditions for Particular Regions

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)

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.

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

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'

Check the boundary condition specification on face 3.

findBoundaryConditions(model.BoundaryConditions,'Face',3)

ans = 
  BoundaryCondition with properties:

           BCType: 'mixed'
       RegionType: 'Face'
         RegionID: 3
                r: [3x1 double]
                h: [3x3 double]
                g: [3x1 double]
                q: [3x3 double]
                u: []
    EquationIndex: []
       Vectorized: 'off'

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: [3x1 double]
                q: []
                u: []
    EquationIndex: []
       Vectorized: 'off'

Input Arguments

BCs — Boundary conditions of a PDE model

BoundaryConditions property of a PDE model

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

Example: model.BoundaryConditions

RegionType — Geometric region type

'Face' for 3-D geometry | 'Edge' for 2-D geometry

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

RegionID — Geometric region ID

vector of positive integers

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

BCregion — Boundary condition for a particular region

BoundaryCondition object

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