Industrial Applications
Authors: Liosi Alexandra , Dunn Harry , Mallik Wrik 
Published: June 2024

This session comprises the following talks
1. Current Capabilities for Implicit Large Eddy Simulations on Industrial Geometries using Spectral h/p Element Methods
2. Vortex dynamics in small scale vertical-axis wind turbine
3. Computational modelling of underwater ocean acoustic propagation with Nektar++

Current Capabilities for Implicit Large Eddy Simulations on Industrial Geometries using Spectral h/p Element Methods

The requirements for performing Large Eddy Simulations (LES) using high-order spectral h/p element methods around complex geometries at high Reynolds numbers are investigated, focusing on the development and evolution of vortical systems. LES typically employs either a model in the near-wall region or a filter to exclude small-scale information, which can be challenging to fine-tune in order to capture the load, transition mechanism, and formation of vortical structures. High-order methods are a promising alternative for conducting wall-resolved LES without the necessity of a wall model or a filter. However, these methods introduce different concerns relevant to numerical accuracy, the influence of the stabilization on the flow resolution, and computational cost. To address these concerns, an industrial benchmark, the Imperial Front Wing (IFW), is examined. We use the high-order velocity correction splitting scheme to solve the incompressible Navier-Stokes equations with a moderate Reynolds number of 2.2 × 10^5. Initially, the numerical configuration for this industrial test case is presented. Its computational performance is assessed based on time to solution, the solver's performance for the algebraic system of equations, and potential speed-up. For validation, the time-averaged numerical results are compared against experimental data. The flow features are further analyzed, and their transient nature is correlated against the experimental survey by Pegrum. This study extends the data set provided by Buscariolo et al. and provides guidelines for performing LES simulations using high-order methods within an industrial environment.

Vortex dynamics in small scale vertical-axis wind turbine

Simulation of vertical-axis wind turbines (VAWT) is challenging due to the high-speed rotation of the blades and complex high-Reynolds number turbulent flow with massive separation involved. With wind energy being earmarked for powering human settlements on Mars, it is crucial to understand how these challenges will be impacted by the low-density Martial atmosphere. Addressing such problems requires an efficient numerical approach to robustly handle the dynamics of the geometry while accurately predicting the flow dynamics unique to Mars. The present work presents a framework using moving reference frame formulation (MRF) of Navier-Stokes (NS) equations. The MRF method is based on the absolute velocity formulations in a non-inertial frame, providing further robustness and stability for numerical simulation. The flow equations are discretised using the high-order spectral/hp element method within the Nektar++ framework. Turbulent flow is modelled using implicit LES method to accurately predict the anisotropic and massively separated flow over the blades.

Accounting for the low kinematic viscosity of the Martial atmosphere, simulations have been conducted for Reynolds Number, Re, to order of O(10^3 )-O(10^4 ). These simulations replicate the Martial atmospheric conditions, demonstrating the solvers capability for and extending high-order methods to industrial applications on Mars.

Computational modelling of underwater ocean acoustic propagation with Nektar++

Underwater radiated noise from shipping activities and offshore wind turbine construction/operation acts as a stressor for marine mammals. Thus, there is an urgent need to develop accurate underwater noise source characterisation and prediction capability of underwater radiated noise to regulate industrial marine activities. Existing practices for routine numerical modelling of underwater ocean noise still rely on hybrid numerical-analytical techniques (e.g., ray tracing), which cannot capture complex wave propagation physics. This motivates the development of more accurate computational models, which can capture the multiscale/multiphysics nature of underwater ocean acoustics. This talk will present some of the early computational modelling efforts on underwater ocean acoustic propagation using the acoustic perturbation equation solver of Nektar++. Some results on multipolar and broadband acoustic propagation modelling will be presented. The talk will also highlight some limitations of the present solver and discuss potential way forward towards development of more accurate modelling approaches for underwater ocean acoustics.