[firenze13574]

Hi all - hope the guys doing the Ohio river sim are reading this

I'm trying to get working an unsteady simulation model of a 130 km river reach that drops about 900 m. The flow data is given in daily intervals for 100 days and intially set the computation interval as 1 day.

At the moment it goes unstable within a few days of simulation-time. I have tried reducing the computation interval to no avail. The error log has lots of warnings such as:

"Warning: The velocity head has changed by more than 0.5 ft (0.15 m). This may indicate the need for additional cross sections.
Warning: The energy loss was greater than 1.0 ft (0.3 m). between the current and previous cross section. This may indicate the need for additional cross sections."

How seriously should take these error messages? I've got XS at 2 km intervals, meaning that the overall gradient between XS is 0.007. If I were to put in enough cross sections so that the energy loss between them is less than 0.3 m I would need on average one every 42 m! Is this really necessary? Or is there something else I should be checking?

Thanks,

Matty