Development of a High-Order Generalised Differential Quadrature Element Method & its Applications

ABSTRACT

Accurate and efficient simulation of complex flow phenomena remains a cornerstone of modern computational fluid dynamics (CFD), especially for applications involving complex geometries and multiscale dynamics. In this seminar, I will present the development and applications of a novel high-order Generalised Differential Quadrature Element (GDQE) method. The GDQE method combines high-order accuracy with compactness and geometric flexibility by decomposing the computational domain into unstructured elements and applying locally high-order differential quadrature (DQ) discretisation. Inter-element fluxes are consistently evaluated using kinetic-based solvers, including the Lattice Boltzmann Flux Solver (LBFS) and the circular function-based Bhatnagar–Gross–Krook (CBGK) scheme. Applications span a wide range of flow problems—from canonical incompressible flows to hypersonic flows in near-vacuum states. The method also shows strong potential for three-dimensional turbulence simulations. Results demonstrate that the GDQE framework achieves high-order accuracy, good efficiency, and excellent robustness across diverse flow regimes.

Enhanced Numerical Framework for Simulation of Ice Accretion in Unsteady & Inhomogeneous Environment

ABSTRACT

An aircraft flying in an icing environment is susceptible to ice accretion that would continuously degrade its aerodynamic performance, leading to eventual or sometimes sudden loss in lift and control. Thus, accurate and robust numerical tools to simulate such complex three-phase flow phenomena are highly sought after by aircraft designers. Past numerical studies often predict ice accretion under a steady freestream condition, and assume exposure to a constant, homogeneous icing environment. In practice, high risk of ice accretion is usually observed over a narrow range of altitude with an abundant presence of supercooled water droplets, which are the culprit of ice formation. Meteorologically, such region is called the “icing layer”. Consequently, an aircraft would be more susceptible to ice accretion during the climbing or the landing phase as it traverses the “icing layer”, rather than during flight at the higher cruise altitude. Ice accretion is usually simulated with a loosely-coupled, iterative approach, commonly known as the multishot framework. Due to the continuous build-up of ice during the iterative simulation, a remeshing step is crucial to maintain the mesh quality. An enhanced framework has thus been developed to provide a robust and fast remeshing routine for ice accretion on an airfoil. The ability to prescribe time-dependent freestream and icing conditions is also incorporated into the enhanced framework, enabling the simulation of ice accretion during climbing and landing with altitude-varying conditions. In this presentation, ice accretion on an RG-15 airfoil exposed to both rime and glaze ice conditions, with and without an altitude-varying liquid water content (LWC), will be discussed. LWC is a measure of the concentration of supercooled water droplets in the atmosphere, and it is a key parameter dictating the icing severity. Depending on the vertical profile of LWC, predicting ice accretion under a constant LWC may under- or over-predict the ice growth, as well as the associated aerodynamic performance degradation.