New high-resolution-preserving sliding mesh techniques for higher-order finite volume schemes

Abstract

This paper presents a new sliding mesh technique for the computation of unsteady viscous flows in the presence of rotating bodies. The compressible Euler and incompressible Navier-Stokes equations are solved using a higher-order (>2) finite volume method on unstructured grids. A sliding mesh approach is employed at the interface between computational grids in relative motion. In order to prevent loss of accuracy, two distinct families of higher-order sliding mesh interfaces are developed. These approaches fit naturally in a high-order finite volume framework. To this end, Moving Least Squares (MLS) approximants are used for the transmission of the information from one grid to another. A particular attention is paid for the study of the accuracy and conservation properties of the numerical scheme for static and rotating grids. The capabilities of the present solver to compute complex unsteady vortical flow motions created by rotating geometries are illustrated on a cross-flow configuration.

Impact of Environmental Turbulence on the Performance and Loadings of a Tidal Stream Turbine

“…The common strategies used to represent tidal turbines are Geometry Resolved (GR) approaches and actuator techniques, such as actuator disk or actuator line [35]. The most frequent GR method is based on body-fitted meshes [34] in which the turbine geometry is embedded into the fluid domain and it is moved using sliding-mesh techniques [36,37]. Body-fitted GR simulations feature a great accuracy to predict the physics of the flow around tidal turbines although their main inconvenience is the large computational cost due to variable re-allocation processes at each time step.…”

An immersed boundary-based large-eddy simulation approach to predict the performance of vertical axis tidal turbines

“…The methodology couples dynamically a Lagrangian-based solid turbine to the Eulerian-based fluid and 95 avoids expensive computational processes that arise when using blade-resolved methods, e.g. variable reallocation and/or interpolation at every time step [25].…”

“…However, in a tidal stream environment vertical axis tidal turbines (VATTs) offer several advantages: (1) they are omni-directional, i.e. their op-20 eration and efficiency is independent of the flow direction; (2) they rotate at lower Tip Speed Ratio (TSR) than HATTs, which is believed to be environmentally more friendly reducing noise generation [4] and fish mortality [5], and supposedly works better in low-to-medium tidal velocities as the cut in speed is lower; and (3) they can make better use of shallow tidal stream flows as they 25 maximise the use of the available cross-section. However, their efficiency is lower than horizontal axis turbines and self-starting could be problematic [6].…”

“…VATT subjected to laminar flowThe first validation test of the IB-based LES approach is a three-bladed Darrieus turbine subjected to laminar flow. This VATT has been simulated 175 previously with sophisticated body-fitted CFD models by Ferrer et al[51] and Ramirez et al[25] who employed a high-accuracy Galerkin method and a high-order finite volumes method, respectively, and their results are used for model comparison. The chosen test case allows quantitative assessment of the accuracy of the predictions of normal and tangential forces and the method's ability to 180 resolve the fluid-structure interaction which generates the torque at the turbine shaft.…”

Toward a near-field CAA-CFD coupling approach: Application to a centrifugal blower

“…Since the grid rotates, this biased stencil formulation avoid both the search of neighbours and the computation of the MLS shape functions at each time step. This strategy which preserves the order of accuracy of the numerical scheme is detailed by Ramírez et al [2015] and .…”