Simulating the fluid forces and fluid-elastic instabilities of a clamped–clamped cylinder in turbulent axial flow

Abstract

In this article, the fluid forces and the dynamics of a flexible clamped-clamped cylinder in turbulent axial flow are computed numerically. In the presented numerical model, there is no need to tune parameters for each specific case or to obtain coefficients from experiments. The results are compared with the dynamics measured in experiments available in literature. The specific case studied here consists of a silicone cylinder mounted in axial water flow. Computationally it is found that the cylinder loses stability first by buckling. The threshold for buckling is in quantitative agreement with experimental results and weakly-nonlinear theory. At higher flow speed a fluttering motion is predicted, in agreement with experimental results. It is also shown that even a small misalignment between the flow and the structure can have a significant impact on the dynamical behavior. To provide insight in the results of these fluid-structure interaction simulations, forces are computed on rigid inclined and curved cylinders, showing the existence of two different flow regimes. Furthermore it is shown that the inlet turbulence state has a non-negligible effect on these forces and thus on the dynamics of the cylinder.

Numerical Investigation of Fluid Forces Acting on a Confined Cylinder with Obstacle Subjected to Axial Flow

“…Ersdal and Faltinsen [22] showed that the lift coefficient depends closely on the Reynolds number. De Ridder et al [23] reached the same conclusions as Ersdal and Faltinsen [22] and Divaret et al [21] numerically. From the literature, it is difficult to estimate the damping of a structure under axial flow as the range of value for Cn and the dependency on various parameters seems wide.…”

Predicting modal characteristics of a cluster of cylinders in axial flow: From potential flow solutions to coupled CFD–CSM calculations

“…Solitary cylinders display this linear dependency of the viscous force on the angle of attack only if the apparent angle of attack is below 2 degrees (De Ridder et al, 2015;Divaret et al, 2014). At higher angles, the force becomes quadratically dependent on the angle of attack.…”

“…At even higher flow velocity (not shown on the graph), the eigenfrequency goes to zero, and the cylinders will buckle. Note that a solitary cylinder behaves similarly (De Ridder et al, 2015;Modarres-Sadeghi et al, 2008).…”

“…This analysis was subsequently used to predict fluidelastic instabilities of a flexible cylinder in axial flow, which was more accurate than weakly non-linear theory (De Ridder et al, 2015).…”

A study of the vibration of a horizontal U-bend subjected to an internal upwards flowing air–water mixture

“…This method is implemented in the in-house coupling code Tango, which handles the communication between the flow solver and the structural solver. The code Tango has been programmed in C++ and has been validated for a number of different applications (Annerel et al (2014); De Ridder et al (2015Ridder et al ( , 2017), including the simulation of sloshing in a tank where the fluid subproblem was modelled with the VOF technique (Degroote et al (2010)) similar to the method applied in the flow problem presented in this paper. As both solvers are commercial codes and therefore are black-box solvers, the Jacobian of the FSI-system is unknown.…”