"Zero normal force imposed" means that normal force and tangential velocity vanish at the outflow boundary. The "zero normal force" condition includes a pressure term.

"Zero normal derivative on velocity imposed" means that normal derivative on velocity and tangential velocity vanish at the outflow boundary.
The pressure is excluded with this condition.

For the temperature field, outflow boundary conditions correspond to a vanishing heat flux.

For viscoelastic flow problems, a fully developed outflow velocity profile is imposed, calculated on the basis of the current model.
The flow rate is specified by the user.