add DiffusionDirichlet boundary condition

Add a Dirichlet boundary condition for Advection-Diffusion problems.

lbmpy/boundaries/boundaryconditions.py

@@ -79,6 +79,11 @@ class LbBoundary:
     def name(self, new_value):
         self._name = new_value
 
+    def __eq__(self, other):
+        if isinstance(other, type(self)):
+            return self.__dict__ == other.__dict__
+        return False
+
 
 # end class Boundary
 
@@ -98,10 +103,7 @@ class NoSlip(LbBoundary):
 
     def __call__(self, f_out, f_in, dir_symbol, inv_dir, lb_method, index_field):
         return Assignment(f_in(inv_dir[dir_symbol]), f_out(dir_symbol))
-
-    def __hash__(self):
-        return hash(self.name)
-
+    
 # end class NoSlip