A bubbler is cooling system component. It is a central circular channel that can be introduced into the mould and is used to regulate and direct the passage of coolant fluid, so that the coolant can travel into difficult areas for more efficient cooling. The coolant flows through the central channel and then out and around the outside of the channel to the outlet point.

Both baffles and bubblers have the effect of increasing flow turbulence and thus increasing heat transfer due to the inclusion of additional bends in the coolant flow system. Their geometrical shape also enables the application of cooling to restricted areas.