Setting initial conditions to understand the saturation of sediments
 

Hello. I am simulating the laboratory conditions of scouring around the bridge abutment in flow 3d software, in the laboratory flume, the sediments are saturated by water flow for some time and about 3-4 cm of water is placed on the sediments, and then the test is started in the constant flow mode, the flume Considering a length of 10 meters, 2 meters of its middle length is sedimentary and the rest of the length is non-erodible(To reduce simulation time, not all flume lengths are considered). Also, the height of the sediments is 20 cm. Should I choose the height of the water from 20 to 23 in setting the initial conditions or from 0 to 23 ? Is it correct to choose the height of water in the initial conditions from the bottom of the flume to 3 cm above the sediments to understand the saturation of the soil for the software?
I expressed my meaning in the attached pictures. Thank
#flow 3d
#initial setting