BoundaryCondition Properties

Boundary condition for PDE model

A BoundaryCondition object specifies the type of PDE boundary condition on a set of geometry boundaries. A PDEModel object contains a vector of BoundaryCondition objects in its BoundaryConditions property.

Specify boundary conditions for your model using the applyBoundaryCondition function.

Properties

BCType — Type of boundary condition

'dirichlet' | 'neumann' | 'mixed'

Boundary type, returned as 'dirichlet', 'neumann', or 'mixed'.

Example: applyBoundaryCondition(model,'dirichlet','Face',3,'u',0)

Data Types: char

RegionType — Geometric region type

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

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

Example: applyBoundaryCondition(model,'dirichlet','Face',3,'u',0)

Data Types: char | string

RegionID — Geometric region ID

vector of positive integers

Geometric region ID, returned 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: applyBoundaryCondition(model,'dirichlet','Face',3:6,'u',0)

Data Types: double

r — Dirichlet condition h*u = r

zeros(N,1) (default) | vector with N elements | function handle

Dirichlet condition h*u = r, returned as a vector with N elements or a function handle. N is the number of PDEs in the system. For the syntax of the function handle form of r, see Nonconstant Boundary Conditions.

Example: 'r',[0;4;-1]

Data Types: double | function_handle
Complex Number Support: Yes

h — Dirichlet condition h*u = r

eye(N) (default) | N-by-N matrix | vector with N^2 elements | function handle

Dirichlet condition h*u = r, returned as an N-by-N matrix, a vector with N^2 elements, or a function handle. N is the number of PDEs in the system. For the syntax of the function handle form of h, see Nonconstant Boundary Conditions.

Example: 'h',[2,1;1,2]

Data Types: double | function_handle
Complex Number Support: Yes

g — Generalized Neumann condition n·(c×∇u) + qu = g

zeros(N,1) (default) | vector with N elements | function handle

Generalized Neumann condition n·(c×∇u) + qu = g, returned as a vector with N elements or a function handle. N is the number of PDEs in the system. For scalar PDEs, the generalized Neumann condition is n·(c∇u) + qu = g. For the syntax of the function handle form of g, see Nonconstant Boundary Conditions.

Example: 'g',[3;2;-1]

Data Types: double | function_handle
Complex Number Support: Yes

q — Generalized Neumann condition n·(c×∇u) + qu = g

zeros(N) (default) | N-by-N matrix | vector with N^2 elements | function handle

Generalized Neumann condition n·(c×∇u) + qu = g, returned as an N-by-N matrix, a vector with N^2 elements, or a function handle. N is the number of PDEs in the system. For the syntax of the function handle form of q, see Nonconstant Boundary Conditions.

Example: 'q',eye(3)

Data Types: double | function_handle
Complex Number Support: Yes

u — Dirichlet conditions

zeros(N,1) (default) | vector of up to N elements | function handle

Dirichlet conditions, returned as a vector of up to N elements or as a function handle. If u has less than N elements, then you must also use EquationIndex. The u and EquationIndex arguments must have the same length. If u has N elements, then specifying EquationIndex is optional.

For the syntax of the function handle form of u, see Nonconstant Boundary Conditions.

Example: applyBoundaryCondition(model,'dirichlet','Face',[2,4,11],'u',0)

Data Types: double
Complex Number Support: Yes

EquationIndex — Index of the known u components

1:N (default) | vector of integers with entries from 1 to N

Index of the known u components, returned as a vector of integers with entries from 1 to N. EquationIndex and u must have the same length.

Example: applyBoundaryCondition(model,'mixed','Face',[2,4,11],'u',[3,-1],'EquationIndex',[2,3])

Data Types: double

Vectorized — Vectorized function evaluation

'off' (default) | 'on'

Vectorized function evaluation, returned as 'on' or 'off'. This evaluation applies when you pass a function handle as an argument. To save time in function handle evaluation, specify 'on', assuming that your function handle computes in a vectorized fashion. See Vectorization. For details of this evaluation, see Nonconstant Boundary Conditions.

Example: applyBoundaryCondition(model,'dirichlet','Face',[2,4,11],'u',@ucalculator,'Vectorized','on')

Data Types: char