In this project, scientists study the aerodynamics of spaceships during entry into the Earths atmosphere using high-precision flow simulations with very accurate physical-chemical models. The simulations take into account thermal and chemical degradation of the heat shield to examine the impact of this surface ablation on laminar flow, disturbance development, and transition to turbulence. Understanding the influence of these phenomena is crucial for designing the thermal protection system of spacecraft.

Aircraft fuel consumption and emissions can be reduced by maintaining laminar flow on the wings. Breakdown of the desirable laminar flow and transition to turbulence is initiated by the crossflow instability of the boundary layer on swept wings. The goal of this project is to study the effect of steps, which occur at panel joints, on the evolution of this crossflow instability. The expected results will help to design more efficient wings.

Aircraft fuel consumption and emissions can be reduced by maintaining laminar flow on the wings. Breakdown of the desirable laminar flow and transition to turbulence is initiated by the crossflow instability of the boundary layer on swept wings. The goal of this project is to study the effect of steps, which occur at panel joints, on the evolution of this crossflow instability. The expected results will help to design more efficient aircraft.

This project aims to investigate the flow dynamics of large wind farms by Large Eddy Simulation. We plan up to 35 wind farm simulations that are categorized into four batches based on the research questions of this project. Besides proposing guidelines to set up simulations including atmospheric gravity waves, we will explore the contribution of these waves towards the global blockage effect and wakes propagation.

The process of laminar to turbulent transition is instrumental in flow physics, not only due to the complex governing mechanisms, but also due to its substantial impact in energy efficiency, greenhouse gas emissions and acoustic noise radiation of many engineering systems. When considering boundary layers, laminar to turbulent transition is primarily dominated by convective (mass-transferring) wave-like instabilities, known as Tollmien-Schlichting waves (TS-waves). As TS-waves propagate in the boundary layer, they grow in amplitude and eventually break down to turbulence. The motivation of substantial past and ongoing research has been to control the amplitude growth of TS-waves in order to postpone transition thus, reducing turbulence and, hence, alleviating its impact on aerodynamic drag and noise. The proposed research differentiates itself from past attempts to control TS-waves, by intersecting for the first time the concept of Metamaterials and fluid flow transition. In spite of their name, metamaterials are not new materials, rather are composed by small engineered units (meta-atoms) that are periodically arranged in space. The meta-atoms often exhibit multiple resonances or anti-resonances that bestow the metamaterial unusual dispersion characteristics such as negative index of refraction, negative dynamic mass density or negative bulk modulus. The novelty brought by the proposed research relies on the realisation that TS instabilities are wave-like structures with monochromatic characteristics, matching well with metamaterials that are well established to excel as classical wave manipulators at narrow frequency bands. The main objective of this research is to investigate whether and how metamaterial concepts can be used to manipulate non-classical convective waves in transitional fluid flows, with the ultimate goal of delaying transition. To answer this question, a combined theoretical, numerical and experimental methodology is proposed. Theoretical coupled models of flow transition and meta-atoms will be formulated and used to design a series of metamaterial concepts. These concepts will be validated using multi-physics numerical simulations, resolving flow and structural dynamics. Combining the theoretical predictions and numerical validation, prototypes of metamaterial surfaces will be fabricated and tested experimentally in wind tunnel conditions, using state-of-art flow diagnostics. The most impacting outcome of this research is, therefore, the introduction of a new class of metamaterials: fluidic metamaterials. This necessitates the foundation of novel theoretical background that delineates this new class, thus bringing forward a principal advance in the physics of metamaterials. The new insights will shed light into the interaction between flow instabilities and metamaterials, and establish whether the latter can be used for control of fluid flows. The high-fidelity models and measurements of this interaction along with new wall-flow boundary conditions and scaling parameters will be utilised for the development of functional prototypes of the novel fluidic metamaterials, demonstrating beneficial control of transitional processes in an experimental environment. In the long term, the proposed research can lead to the development of fluidic metamaterial surfaces, deployed to a wealth of flow systems, significantly reducing the adverse effects of turbulence regarding fuel consumption, emissions and acoustic noise.