volumetric conservation equation in PHOENICS code

mehdi

In case of the two methods HOL and SEM implemented in PHOENICS code for simulating free surface flows, the continuity equation was formulated in term of volumetric conservation as

D(Ln(RHO))/Dt+du/dx+dv/dy+dw/dz=0.

REF: Free surface flow and heat transfer in cavities: the sea algorithm, K.A Percilious & al 1995 ,Numerical heat transfer Part B, 27:487-507, 1995

1- what are the steps followed to discretise this equation by finite volume method ?

2- What is the discretized form of this equation ?

Thank you.