Numerical modeling of open channel flows with moving fronts using a variable boundary formulation

Modeling flows in open channels with explicit family of schemes is constrained by the choice of time step, which is limited by the Courant Friedrichs Lewy stability condition. For simulations over large spatial domains or long time durations, this limitation reflects in increased computational time. To address this limitation, in this work the affect of using varying boundary locations at both the upstream and downstream ends in the numerical code is investigated. The location of the two boundaries in this approach is an evolving function with time and not fixed as in the standard implementations. Such a formulation will aid in solving the flow equations over reduced number of nodes at every time, thus accelerating the solution to the desired state. The performance of this approach for modeling transient and stationary waves for mixed flow conditions is investigated. The results indicate that this approach can significantly accelerate the solution with out affecting its accuracy.