Abstract
A fluid–structure interaction (FSI) methodology is presented for simulating elastic bodies embedded and/or encapsulating viscous incompressible fluid. The fluid solver is based on finite volume and the large eddy simulation approach to account for turbulent flow. The structural dynamic solver is based on the combined finite element method–discrete element method (FEM-DEM). The two solvers are tied up using an immersed boundary method (IBM) iterative algorithm to improve information transfer between the two solvers. The FSI solver is applied to submerged vegetation stems and blades of small-scale horizontal axis kinetic turbines. Both bodies are slender and of cylinder-like shape. While the stem mostly experiences a dominant drag force, the blade experiences a dominant lift force. Following verification cases of a single-stem deformation and a spinning Magnus blade in laminar flows, vegetation flexible stems and flexible rotor blades are analysed, while they are embedded in turbulent flow. It is shown that the single stem’s flexibility has higher effect on the flow as compared to the rigid stem than when in a dense vegetation patch. Making a marine kinetic turbine rotor flexible has the potential of significantly reducing the power production due to undesired twisting and bending of the blades. These studies point to the importance of FSI in flow problems where there is a noticeable deflection of a cylinder-shaped body and the capability of coupling FEM-DEM with flow solver through IBM.
Highlights
Fluid–structure interaction (FSI) is a topic spanning through many engineering disciplines from aeronautics and renewable energy to biomedical engineering and particle transport
The FSI code has already been extensively verified in previous publications [10, 18,19,20,21,22,23], and only verifications specific to the class of the investigated cases are shown followed by results of interest
This ca√n be justified by assuming a low Froude number Fr = US∕ gH, i.e. less than 0.5, where US is the typical velocity at the top of the channel and H is the depth of the channel [25]
Summary
Fluid–structure interaction (FSI) is a topic spanning through many engineering disciplines from aeronautics and renewable energy to biomedical engineering and particle transport. The reduced-order modelling has been found successful in various problems ranging from wings flutter to feathering of wind turbine blades, it has limitations in terms of the simplified assumptions used in the fluid and solid dynamics. Extensions to include large deformations and computational fluid dynamic (CFD) results through reduced-order modelling have been suggested [1], but they point to the need for a full computational FSI solver. Such solvers exist as monolithic or partitioned [4, 5]. An example is the use of the structural dynamics Y-Code based on the combined finite element
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