[abhnv_sngh]

hello,
I am working with 2-D transient simulation with compressible flow, gravity assisted.
I am using VOF- multiphase model and evaporation condensation model as the phase change model, with saturation temperature as a function of saturation pressure.
liquiq is primary phase and Vapor is secondary phase.
liquid properties - piece-wise polynomial function of temperature
vapor density - Ideal gas
vapor viscosity and thermal conductivity - piece-wise poly function of temperature.

Operating pressure - 0, gauge pressure - 76043 Pa
Operating density - 0 kg/m3

Initial temp - 75K

CONVERGANCE criteria -
(continuity - 1e-05), (velocity - 1e-04) and (energy - 1e-06)

SOLUTION METHODS
Pressure-velocity coupling - PISO
Gradient - Least squares cell based
Pressure - Body force weighted
Density - second order upwind
Momentum - Quick
Volume fraction - geo-reconstruct
Energy - first order upwind

All the URFs are default.

why is total mass changing with time and also the continuity residual falls in the range of 1e-01 to 1e+02?