[en] The modified hydrodynamic approach is being used to study the characteristics of plasma motion due to magnetic pressure in plasma opening switch. The simulation code differs from the NRL counterpart with dividing of the plasma filled region into N sections and with using the experimentally measured current penetration parameters. The simulation of the switch opening phase is performed in terms of erosion mechanism of magnetically insulated vacuum gap forming. The code includes the circuit data which are regular for the DOUBLE generator operation regimes in the negative polarity of inner (potential) electrode. In the case of typical duration of the conduction phase (900 ns) the minimum needed plasma density was found to be about 10¹⁵ cm^-3. The best fit of conduction current amplitude vs plasma density is I ∼ n^0.23. The calculated characteristics of the switch opening phase were obtained to be very close to the experimental data