The name MULTIWIR (wir [vi:r] is Polish for vortex) is derived from a phenomenon of multiple vortices induced in the gas stream flowing through a specifically organized packing. The packing consists of parallel strips arranged such that strips of adjacent layers cross at a certain angle. This construction causes the flowing gas to divide into multiple small rotating streams.
So far two main forms of Multiwir structured packings have been applied in the industry: the rectangular and the annular. The rectangular packing consists of layers of parallel straight strips. The annular form is built from curved strips and permits radial gas flow.

The stream of inlet gas entering the packing divides into many small streams flowing along the passages between the strips. The streams flowing between strips of adjacent layers of the packing come into contact with each other at a certain angle and, as a result of momentum transfer, a forced rotational flow takes place. The angular velocity of the rotation has been experimentally proved to be constant. The frequency of revolutions depends on gas velocity. In practical applications, the radius of the vortices equals 15 ÷ 25 mm and its frequency is contained within the range 30 ÷ 60 s^-1.

The centrifugal force resulting from the rotational flow of gas streams is the main factor responsible for the separation process of droplets and solid particles. The separation efficiency depends on precise packing construction parameters and on gas velocity. The highest grade of separation observed experimentally reached 90 ÷ 100 % within the range of particle diameter grater than 0,2 µm.

The research on separation efficiency of Multiwir packings was carried out at Technical University of Lodz in Poland and Technical University of Clausthal in Germany. Currently investigations are taking place in Germany at the universities in Karlsruhe, Stuttgart and Essen.

Multiwir packings are being produced from stainless steel and polypropylene.