Handling namespace models (classes) in namespace
The
models/ns1/articles.rb
is basically setting the table name prefix for all the model classes under that namespace. Thats its use. It's more DRY'ish to do in there (in a single file), rather than setting the prefix in every model class under that namespace.
I am not a big fan of using namespaces in my models. However you could refer to the following articles to gain a better understanding about using namespaces in modules.
Some alternatives to using namespaces in models
Hope this helps.