This study presents Computational Fluid Dynamics (CFD) simulation analyses and Particle Image Velocimetry (PIV) experimental research on two-sided (symmetrical) filling of whirlpool separator's tank and swirling the liquid. This innovative approach enables flow symmetrization and more efficient use of the secondary flow, which causes the hot trub cone formation. The results of the CFD analyses were verified during the experimental research incorporating image anemometry (PIV) and a laboratory scale model. The results were compared to the data obtained from the CFD and PIV performed on a typical model with single-sided filling. The comparison clearly proved the advantage of the two-sided filling in terms of timing and position of the secondary flow, which causes the hot trub cone formation in a whirlpool separator. (C) 2014 Elsevier Ltd. All rights reserved.