Update 07_functions_on_subdomains.ipynb

Changed the sign on the coupling between pressure and stress, such that the correct physical boundary conditions are respected.

Author: CaioVSS2000

examples/userapi/07_functions_on_subdomains.ipynb

@@ -2848,10 +2848,10 @@
     "eq_t = Eq(tau.forward, solve(pde_tau, tau.forward), subdomain=lower)\n",
     "\n",
     "# Coupling: p -> txx, tyy\n",
-    "eq_txx_tr = Eq(tau[0, 0].forward, p.forward, subdomain=uppertransition)\n",
-    "eq_tyy_tr = Eq(tau[1, 1].forward, p.forward, subdomain=uppertransition)\n",
+    "eq_txx_tr = Eq(tau[0, 0].forward,- p.forward, subdomain=uppertransition)\n",
+    "eq_tyy_tr = Eq(tau[1, 1].forward,- p.forward, subdomain=uppertransition)\n",
     "# Coupling: txx, tyy -> p\n",
-    "eq_p_tr = Eq(p.forward, (tau[0, 0].forward + tau[1, 1].forward)/2, subdomain=lowertransition)"
+    "eq_p_tr = Eq(p.forward, - (tau[0, 0].forward + tau[1, 1].forward)/2, subdomain=lowertransition)"
    ]
   },
   {