Abstract The discrete-fracture numerical model FRAC3DVS has been enhanced to simulate thermohaline variable-density flow and solute transport in fractured porous media. A general formulation of the buoyancy term has been derived to simulate density effects in irregular networks of discrete fractures with arbitrary incline. The model allows the investigation of variable-density flow in more disorganized fractured media than previously possible. A series of simulations in different, yet statistically equivalent, fracture networks has been conducted and show that solute migration is highly sensitive to the properties of the network. A sensitivity analysis reveals that low fracture apertures, low matrix permeability, high matrix porosity and large molecular diffusion, tend to stabilize solute migration.

Keywords fractured rock; FRAC3DVS; numerical modelling; variable-density flow