Real Time Wake Computations using Lattice Boltzmann Method on Many Integrated Core Processors

This paper puts forward an efficient Lattice Boltzmann method for use as a wake simulator suitable for real-time environments. The method is limited to low speed incompressible flow but is very efficient and can be used to compute flows “on the fly”. In particular, many-core machines allow for the method to be used with the need of very expensive parallel clusters. Results are shown here for flows around cylinders and simple ship shapes

Real Time Wake Computations using Lattice Boltzmann Method on Many Integrated Core Processors

This paper puts forward an efficient Lattice Boltzmann method for use as a wake simulator suitable for real-time environments. The method is limited to low speed incompressible flow but is very efficient and can be used to compute flows “on the fly”. In particular, many-core machines allow for the method to be used with the need of very expensive parallel clusters. Results are shown here for flows around cylinders and simple ship shapes

Assessment and calibration of the γ equation transition model for a wide range of Reynolds numbers at low Mach

The numerical simulation of flows over large-scale wind turbine blades without considering the transition from laminar to fully turbulent flow may result in incorrect estimates of the blade loads and performance. Thanks to its relative simplicity and promising results, the Local-Correlation based Transition Modelling concept represents a valid way to include transitional effects into practical CFD simulations. However, the model involves coefficients to be tuned to match the required application. In this paper, the γ-equation transition model is assessed and calibrated, for a wide range of Reynolds numbers at low Mach, as needed for wind turbine applications. Different airfoils are used to evaluate the original model and calibrate it, whereas a large-scale wind turbine blade is employed to show that the calibrated model can lead to reliable solution for complex three-dimensional flows. The calibrated model shows promising results for both two-dimensional and three-dimensional flows, even if cross-flow instabilities are neglected

Quantum Algorithms for Nonlinear Equations in Fluid Mechanics

In recent years, significant progress has been made in the development of quantum algorithms for linear ordinary differential equations as well as linear partial differential equations. There has not been similar progress in the development of quantum algorithms for nonlinear differential equations. In the present work, the focus is on nonlinear partial differential equations arising as governing equations in fluid mechanics. First, the key challenges related to nonlinear equations in the context of quantum computing are discussed. Then, as the main contribution of this work, quantum circuits are presented that represent the nonlinear convection terms in the Navier–Stokes equations. The quantum algorithms introduced use encoding in the computational basis, and employ arithmetic based on the Quantum Fourier Transform. Furthermore, a floating-point type data representation is used instead of the fixed-point representation typically employed in quantum algorithms. A complexity analysis shows that even with the limited number of qubits available on current and near-term quantum computers (<100), nonlinear product terms can be computed with good accuracy. The importance of including sub-normal numbers in the floating-point quantum arithmetic is demonstrated for a representative example problem. Further development steps required to embed the introduced algorithms into larger-scale algorithms are discussed

Optimisation of Transonic Circulation Control Devices

Gradient based optimisation of a Coanda surface for a transonic, supercritical circulation control aerofoil is presented. Design variable updates are driven by a Sequential Least Squares Quadratic Programming (SLSQP) algorithm, using gradients provided by the solution of the Adjoint equations in discrete formulation. Surface sensitivities of the lift coefficient relative to local variations on the Coanda shape are shown, which indicate that the effects due to under-expansion of the jet have a significant influence on the circulation control efficiency. It is also shown that a 16\% improvement in the augmented lift coefficient compared with a simple circular shape can be achieved with minor alterations of an initial quasi-elliptical design. A gain in lift coefficient of $C_l = 0.09$ was achieved relative to this initial shape

Parallel Performance for a Real Time Lattice Boltzmann Code

The paper will present the details of a Lattice Boltzmann solver running in real time for unsteady wake computations. In addition to algorithmic implementation, computational results, single core and parallel optimization of the methods are also discussed

Coupling of particle-based and grid-based methods within object-oriented multi-physics CFD framework

A novel multi-physics approach involving mesh-based methods for kinetic-Boltzmann equations coupled with molecular dynamics (MD) simulations of thermal relaxation is introduced. The particle method, its parallel performance and the implemen- tation in MΦC are discussed, including the unification and re-use of the source code for different methods and models. The hypersonic partially rarefied flow of a diatomic gas around a sphere and a spaceplane configuration are considered as examples, providing de- tails about the thermal non-equilibrium conditions to be modelled using MD simulations. The MD results show that existing empirical models may not provide sufficient accuracy for the gas flow in strong expansions and that the proposed method provides a mechanism for improving the accuracy

Brownout Simulations of Model-Rotors In Ground Effect

n this work computational fluid dynamics is used to validate experimental results for a two-bladed small rotor In Ground Effect conditions. The paper focuses on the evaluation and prediction of the rotor outwash generated in ground effect. Time-averaged outflow velocities are compared with experimental results, and the simulated flow field is used for safety studies using the PAXman model and particle tracking methods. The aircraft weights have been studied, evaluating scaling factors to define how helicopter weight can affect the outflow forces and the particle paths. Results show how the wake generated by heavier helicopters can lead to stronger forces on ground personnel and push the particles farther away from the rotor

Research on the drag reduction performance induced by the counterflowing jet for waverider with variable blunt radii

Waverider will endure the huge aero-heating in the hypersonic flow, thus, it need be blunt for the leading edge. However, the aerodynamic performance will decrease for the blunt waverider because of the drag hoik. How to improve the aerodynamic performance and reduce the drag and aero-heating is very important. The variable blunt radii method will improve the aerodynamic performance, however, the huge aero-heating and bow shock wave at the head is still serious. In the current study, opposing jet is used in the waverider with variable blunt radii to improve its performance. The three-dimensional coupled implicit Reynolds-averaged Navier-Stokes(RANS) equation and the two equation SST k–ω turbulence model have been utilized to obtain the flow field properties. The numerical method has been validated against the available experimental data in the open literature. The obtained results show that the L/D will drop 7–8% when R changes from 2 to 8. The lift coefficient will increase, and the drag coefficient almost keeps the same when the variable blunt radii method is adopted, and the L/D will increase. The variable blunt radii method is very useful to improve the whole characteristics of blunt waverider and the L/D can improve 3%. The combination of the variable blunt radii method and opposing jet is a novel way to improve the whole performance of blunt waverider, and L/D can improve 4–5%. The aperture as a novel way of opposing jet is suitable for blunt waverider and also useful to improve the aerodynamic and aerothermodynamic characteristics of waverider in the hypersonic flow. There is the optimal P0in/P0 that can make the detached shock wave reattach the lower surface again so that the blunt waverider can get the better aerodynamic performance

Transonic Buffet Simulation using a Partially-Averaged Navier-Stokes Approach

This work assesses the capability of the partially averaged Navier-Stokes (PANS) method to accurately reproduce self-sustained shock oscillations, also known as transonic buffet, occurring on supercritical aerofoils at high Reynolds numbers. Attention is paid to the comparison with unsteady Reynolds-averaged Navier Stokes (URANS) results to show the benefits of PANS, in resolving flow unsteadiness on affordable CFD grids. The role of the mesh metrics in the formulation of the PANS model is emphasized, as well as the relation of the mesh metrics with the spatiotemporal discretisation used for the numerical simulations. The aim is to extend the use of PANS to flow cases involving shock-wave boundary layer interactions to obtain accurate predictions without the need for very expensive computations