GGU-3D-SSFLOW: Principles

Flow lines can be drawn from the velocities calculated by the finite-element program. The principle used by the program is also known as the course line method or particle-tracking method. With this method a water particle, which wanders through the system from any start point, is observed. The program determines size and direction of seepage from this start point. With this velocity vector, the new position of the particle can be determined, whereby either a "distance increment" or a "time increment" can be selected for calculation of velocity vector length. The new position of the water particle is then the start point for the next calculation step. This procedure is carried on as long as a user-defined end-time is not exceeded, or the particle leaves the system. Small increments mean high precision and long calculation time.

If the increments are too large, nonsensical results can occur. Calculations are performed using the seepage velocity (vs = (k · i)/neff!). Using this program, you can also follow a particle back (against flow direction).