Abstract
We developed predictable model for driftwood motions around obstacles by coupling a three-diemensional CFD model and a Lagrangian type driftwood model. In the present model, three-dimensional flow is solved with Reynolds averaged Navier Stokes equations and the driftwood motion is solved with a Lagrangian approach by modeling a driftwood as a series of spheres. The collision of driftwood is considered with DEM approach. The interaction between driftwood and water is considered by two cases; one-way approach and two-way approach. Only the two-way approach takes into account the drag force from the driftwood to water flow. The computations were performed under the condition of existing laboratory experiment for a dam reservoir. The present model could reproduce general features of driftwood motions around obstacles well. It is important to consider the collisions of driftwood and also two-way approach to estimate precisely the driftwood captureing processes around obstacles.
