Hydrodynamic forces on emergent cylinders in non-uniform flow

Abstract The main objective of conducting numerical simulations flows in rivers with vegetation is to investigate the complex flow dynamics involved non-equilibrium conditions. In such cases, it inappropriate apply drag coefficient C D , which typically derived based on uniform involving groups infinitely long cylinders. This paper presents a method for evaluating forces acting emergent obstacles non-uniform open-channel flows. devised two sets experiments: small-diameter cylinders, focusing water surface profiles through group; and large-diameter local pressure distribution profile around target cylinder. addition conventional force expression that includes new terms are proposed account effects variation gradient drag. first these terms, introduces use Froude number effect variation, theoretically evaluated against past present experimental results under uniform-flow On other hand, second representative length separation zone evaluate gradient, confirmed be necessity calculation longitudinal incorporation using simple unified can help improve accuracy practical problems obstacles.