In the conventional meltblown die system, the twin slot-jets expand freely into atmospheric air. Experimental analysis or even CFD analysis with traditional turbulence models provides only time-averaged fields that mask the unsteady turbulent features of this fast process. Large Eddy Simulation (LES) is an advanced turbulence model, available in FLUENT, that captures the transient eddy structures in the fast attenuation region associated with the twinjet synchronous pull. Slow moving large scale eddies cause downstream entanglement of the cooled fibers.

Instantaneous temperature contours downstream of the meltblown die as predicted by the FLUENT LES model.