Hello everyone ,

I am trying to calculate an integral on the dirichlet boundary, however for some reason I keep getting an error saying “Trialfunction does not support BND-forms, maybe a Trace() operator is misssing”

My geometry is and function space is:

[code] from netgen.geom2d import SplineGeometry

geo = SplineGeometry()

geo.AddRectangle( (0, 0), (0.41, 2), bcs = (“b”, “r”, “t”, “l”))

geo.AddCircle ( (0.2, 1.8), r=0.05, leftdomain=0, rightdomain=1, bc=“cyl”)

mesh = Mesh(geo.GenerateMesh(maxh=0.08))

mesh.Curve(3)

V = VectorH1(mesh,order=3, dirichlet=“t|cyl|l|r”)

Q = H1(mesh,order=2)

X = FESpace([V,Q])

u,p = X.TrialFunction()

v,q = X.TestFunction()

h = specialcf.mesh_size

n = specialcf.normal(2)[/code]

and I want to impose Dirichlet boundary conditions only on the “t” boundary weakly. For that I need to calculate following:

```
a += SymbolicBFI(-nu*InnerProduct(grad(u)*n,v)
-nu*InnerProduct(grad(v)*n,u)
+nu*alpha/h*InnerProduct(u,v),
definedon=mesh.Boundaries("t"))
```

but this calculation gives me the above-mentioned error.

Anyone can see what is going on here?

Thanks in advance.