Simulation of Return Flow in Restricted Navigation Channel for Barge-tow Movements

Simulations of barge-tow movement in the sub-critical range along the Illinois River near Kampsville are performed to determine the return flow (RF) characteristics for upstream and downstream bound barge-tows. Simulations are carried out using the OpenFOAM® based CFD software for six barge-tow configurations considering two-dimensional shallow water equation. The RF velocities are simulated for 0s to 100s at an interval of 10s at nine different locations, taken across the river from vessel to bank for upstream and downstream bound barge-tows. The computed RF velocities at these points between the bow and the bank are analyzed and compared with the observed field data for identical conditions. The simulated RF velocity agrees well with the computed RF velocity of Hochestein and Adams, and Maynord and Siemsen, except closer to the barge-tow. Model simulation shows that the RF profiles (lateral velocity distributions transverse to vessel movement) vary with time and the length of the vessel. To understand the associated phenomena, drawdown and squat are computed using empirical formulations given by earlier researchers. The simulated result clearly indicates the location of the zero velocity point for downstream bound barge-tows. The present study would be helpful to hydraulic engineers, planners and biologists to predict RF hydrodynamic in a restricted channel.