# Get help - Lockfill

**FAQ**

**What levelling systems can be modelled in LOCKFILL?**

Lockfill can handle 6 different levelling systems, namely:

- Gate openings
- Culverts with stilling chamber
- Vertical slit
- Butterfly valves
- Shutter slides
- Lift gate

So, longitudinal filling systems are not possible.

**What discharge coefficient should be used for my levelling system?**

Discharge coeffients are determined by the geometry of the leveling system. The value of this parameter is not known on forehand. Based on experience an educated guess can be made for this value. Sensitivity analysis is required to determine the sensitity of this guess.

It also possible to determine this value. This can be done by physical modelling of your levelling system. However, this requires quite some work. Recent work by Deltares has shown that the discharge coefficient can be determined accurately with CFD.

**What forces are distinguished by LOCKFILL?**

LOCKFILL distinguishes 5 forces, namely forces originating from:

- Translatory wave
- Momentum decrease
- Filling jet
- Friction
- Density differences (not available in the free version)