Constrains using null space in dolfinx

[dokken]

@bagla0

I am getting error to delete cache file to work lhs. After deleting cache file, it starts working. Do I need to do this everytime?

Unfortunately, I cannot reproduce this behaviour.

@bagla0

Getting error in making ufl.form

You are using the wrong form.
You should use dolfinx.fem.form, not ufl.form.
Remove form from

@bagla0

from ufl import TrialFunction, TestFunction, inner, form, lhs, rhs, dx

@bagla0

3b. I got error in c.interpolate. I don’t understand its significance of using x.shape. What should be for this example?

You have a function space V that is a vector function space.
The input to interpolate is a set of coordinates, x, of shape (3, number_of_points), where x[0] is the list of all x-coordinates, x[1] all y coordinates etc.
The input is designed this way so that you can used vectorized functions in numpy.
As your space is a vector space of dim=3, the output should be (3, number_of_points), not just number_of_points.

@bagla0

if I want a constraint like \int dv.dx(0) =0∫dv.dx(0)=0\int dv.dx(0) =0, how can I implement this ?

Not sure why you would want such a constraint, what is the physical interpretation of this.

@bagla0

how can I implement periodic boundary condition. Previously, we give argument in defining function space of mixedelement constrained_domain=PeriodicBoundary(vertices, tolerance=1e-10). I don’t know where should I implement it?
Any help is appreciated in using nullspace.

This is a topic covered in many other posts on discourse, see for instance: Periodic BC in dolfinx - #2 by nate