Physical Modeling and CFD for Design Purposes in the Era of Affordable CFD and 3D Printing

ABSTRACT ONLY - It is well known that the gold standard for analyzing the design of a civil hydraulic structure is a large-scale physical model, although typically costly for consulting work. As an alternative, consulting companies have been using computational fluid dynamics (CFD) to check their designs with a reasonable level of confidence, the drawback being long runtimes. In recent years, other alternatives have been explored, such as 1) the combination of CFD and small-scale physical models or 2) 3D-printed small-scale physical models alone. The work presented will provide insights on this topic through three examples. The first example is a spillway modification in which a large physical model was used to inform the design. An analysis of the cost versus the model capability to answer critical design questions will be shown. The second example is a case study in which a small-scale physical model was compared to a CFD model. In that case study, the occurrence of pressure surges due to entrapped air pockets in a shaft discharging to a long, closed conduit was analyzed. The result of the analysis was used to improve the design and set a level of confidence that previously was not possible. Finally, the third example is a case study in which a small-scale physical model using 3D printing was a good alternative to check a design with a complex geometry. In that case study, the use of more simple numerical tools would not have provided enough level of confidence in the design; and, on the other hand, more sophisticated numerical modeling (e.g., CFD) would have entailed a larger level of effort.