Phoenix FD 4.0 Quick Tutorial - Melting Candle using a Particle Tuner

In this setup the viscosity is reduced by a Particle Tuner based on the distance to a geometry. Once the viscosity is reduced, another Particle Tuner starts gradually increasing it so it would solidify again. The scene scale is exaggerated and the simulator is 1 meter tall for demonstration purpose - if you decrease the simulator scale, the viscosity effect will be reduced, so you can compensate by increasing the Steps per Frame.