Hello there. I am trying to simulate an open channel spillway with flow 3d. my problem is that, since the channel has slope of 9 degrees (the channel starts with a straight passage of 42 cm and continues with a slopped channel of 126cm and 9 degree slope then straightens again for 249 cm more) in the middle part, how can I define the regions so that the water flows correctly? when in the initial conditions I put the water elevation, it shows a plain of water parallel to the bed of channel and its not flowing.