I am working on transient analysis of multiphase water entry body (3-Dimensional) using VOF, k-omega SST turbulence model, with velocity inlet and pressure outlet boundary conditions, overset mesh, dynamic mesh zone conditions, have been used. while running calculations for a time step size of 0.01, number of time steps 100, max iterations as 90 after completing max iterations my continuity residual almost gets a straight line from 15th iteration, rest of all velocities and k, omega residuals get converged which i have taken convergence criterion as 1e-05. what could be the reason for the continuity residual being a straight line?