# 4.9.5. Smoothing Method

There are a few different options for smoothing algorithms to select for the continuity equation, as defined in the theory section on smoothing.

The most common choice, which works well for the majority of problems, is fourth order smoothing with timestep scaling (Equation (3.761), as shown in the example below).

       Begin Solution Options
         Projection Method = Fourth_Order Smoothing with Timestep Scaling

    Another common choice is fourth order smoothing with characteristic scaling (Equation :eq:`numerics-characteristic-scaling`):

    Begin Solution Options
      Projection Method = Fourth_Order Smoothing with Characteristic Scaling

A third, less-common choice is stabilized smoothing, activated using:

    Begin Solution Options
      Projection Method = Stabilized SMOOTHING