NDSolve`FEM`
NDSolve`FEM`

InitializeBoundaryConditions::fembderiv

Details

  • This message is generated in case a spacial derivative is modeled using Derivative instead of NeumannValue.
  • The usage of Derivative to model spatial derivatives with the finite element method is not supported in this version.
  • The section What Triggers the Use of the Finite Element Method explains when the finite element method is selected automatically to solve a differential equation.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[InitializeBoundaryConditions::fembdderiv].

Examples

Basic Examples  (2)

For the finite element, spatial discretization derivatives need to be modeled with NeumannValue:

The solution is to use NeumannValue:

More information on the relation between Derivative and NeumannValue can be found in the section The Relation between NeumannValue and Boundary Derivatives.

An explanation of when the finite element method is automatically chosen by NDSolve can be found in the section What Triggers the Use of the Finite Element Method.

The following PDE automatically chooses the finite element method:

Specify the derivative boundary condition with NeumannValue:

An explanation of when the finite element method is automatically chosen by NDSolve can be found in the section What Triggers the Use of the Finite Element Method.