Initial values on blocks

[Aiden Huffman]

Hi All,

I am trying to setup a "simple" solver for a Stokes-Cahn-Hilliard problem but I've gotten stuck trying to implement the initial conditions for the color/phase function. The problem looks like the following:

Where there's a regularized surface tension where the sharp interface would normally be between two fluids. The separate fluids are tracked through the function c. Using a forward Euler scheme, and introducing a dummy variable for the curvature I end up with

The eventual weak form isn't to important yet, since I can't even build the initial conditions. At first I thought to extend Step-22 and use a block system and solve "chunks" of. In particular, solving the stokes update and then solving for the update to the phase function; but I can't figure out how to set the initial conditions for $c^0$. Now I am wondering if the correct approach is to use FETools and separate DoF handlers similar to Step-35.

Any advice or direction would be greatly appreciated. I've included the very barebones implementation I have right now.

[Aiden Huffman]

I should add that in it's current form I get the following error:

An error occurred in line <425> of file <./include/deal.II/numerics/vector_tools_project.templates
.h> in function
    void dealii::VectorTools::internal::do_project(const M_or_MC<dim, spacedim>&, const dealii::Do
FHandler<dim, spacedim>&, const dealii::AffineConstraints<typename VectorType::value_type>&, const
 Q_or_QC<dim>&, const dealii::Function<spacedim, typename VectorType::value_type>&, VectorType&, b
ool, const Q_or_QC<(dim - 1)>&, bool) [with int dim = 2; int spacedim = 2; VectorType = dealii::Ve
ctor<double>; M_or_MC = dealii::Mapping; Q_or_QC = dealii::Quadrature; typename VectorType::value_
type = double]
The violated condition was:
    dof.get_fe(0).n_components() == function.n_components
Additional information:
    Dimension 6 not equal to 1.

Which makes a ton of sense, I have an FESystem not a simple single finite element. I am just not sure what the right object is, or how to build it.

[Luca Heltai]

The function that defines the initial conditions must contain 6 components, while apparently yours contains only one. 

Luca

Il giorno 18 nov 2023, alle ore 17:29, Aiden Huffman <huffma...@gmail.com> ha scritto:

I should add that in it's current form I get the following error:

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