Nitsche’s Method for boundary and interface conditions#
+13. Nitsche’s Method for boundary and interface conditions#
from netgen.occ import *
@@ -386,6 +421,11 @@ Nitsche’s Method for boundary and interface conditions
+error bc: 0.052752210661407825
+
+
+
Exercises:
-
@@ -394,7 +434,7 @@
Nitsche’s Method for boundary and interface conditions\(u = x+y\) on \(\partial \Omega\)
Nitsche’s method:#
+13.1. Nitsche’s method:#
Nitsche’s method:
+error bc: 3.4214848016971966e-06
+
+
+
error bc: 3.4214848016971966e-06
+
The bilinear-form is coercive w.r.t. the norm induced by \(\int_\Omega \nabla u \nabla v dx + \int_{\partial \Omega} \frac{p^2}{h} u v ds \) if \(\alpha\) is sufficiently large.
We check positive definite by computing the few smallest eigenvalues of
@@ -450,6 +495,15 @@Nitsche’s method:
+ 0.985783
+ 0.987115
+ 0.990019
+ 0.991396
+ 0.995728
+
+
+
0.985783
+ 0.987115
+ 0.990019
+ 0.991396
+ 0.995728
+
Exercise:
-
@@ -459,7 +513,7 @@
Nitsche’s method:
-Interfaces#
+13.2. Interfaces#
Consider an electric motor with a rotating rotor. The fixed and the rotating part are meshed independently, and continuity at the interface is achieved by a Nitsche method.
@@ -523,6 +582,8 @@ Interfaces
+
without gluing together we compute independent solutions for both regions:
@@ -539,6 +600,8 @@ Interfaces
+
The ContactBoundary
class computes integrals between two different boundaries. It integrates over the primary boundary, finds the closest point on the secondary boundary and evaluates the other function there.
@@ -567,12 +630,14 @@ Interfaces
+
The current implementation is very simple and not highly accurate. It uses Gauss-rules on the primary boundary which are accurate for finite element functions on the primary boundary, but not for the other boundary. One can observe oscillations for the gradient near to the boundary.
Interfaces +
Interfaces +
ContactBoundary
class computes integrals between two different boundaries. It integrates over the primary boundary, finds the closest point on the secondary boundary and evaluates the other function there.Interfaces +
Hybrid Interfaces#
+14. Hybrid Interfaces#
In a hybrid interface method one introduces another field \(\hat u\) only at the interface. The functions \(u\) from both sides are glued to this common interface field by a Nitsche method:
Hybrid Interfaces
+('outer', 'inner', 'bar')
+('outer', 'outer', 'outer', 'outer', 'gammao', 'gammai', 'default', 'default', 'default', 'default')
+0: 0000110000
+
+
+
('outer', 'inner', 'bar')
+('outer', 'outer', 'outer', 'outer', 'gammao', 'gammai', 'default', 'default', 'default', 'default')
+0: 0000110000
+